An overview of chemical straightening of human hair: technical aspects, potential risks to hair fibre and health and legal issues

Size: px
Start display at page:

Download "An overview of chemical straightening of human hair: technical aspects, potential risks to hair fibre and health and legal issues"

Transcription

1 International Journal of Cosmetic Science, 2013, 1 10 doi: /ics Review Article An overview of chemical straightening of human hair: technical aspects, potential risks to hair fibre and health and legal issues A. L. Miranda-Vilela*,, A. J. Botelho and L. A. Muehlmann *Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasilia, DF, Brazil, Nanodynamics Consulting and Innovation Ltd, University of Brasilia, Brasilia, DF, Brazil and Beleza Natural Institute, Rio de Janeiro, RJ, Brazil Received 4 June 2013, Accepted 14 September 2013 Keywords: chemical analysis, hair growth, hair treatment, safety testing, straightening Synopsis Personal image, as it relates to external beauty, has attracted much attention from the cosmetic industry, and capillary aesthetics is a leader in consumption in this area. There is a great diversity of products targeting both the treatment and beautification of hair. Among them, hair straighteners stand out with a high demand by costumers aiming at beauty, social acceptance and ease of daily hair maintenance. However, this kind of treatment affects the chemical structure of keratin and of the hair fibre, bringing up some safety concerns. Moreover, the development of hair is a dynamic and cyclic process, where the duration of growth cycles depends not only on where hair grows, but also on issues such as the individual s age, dietary habits and hormonal factors. Thus, although hair fibres are composed of dead epidermal cells, when they emerge from the scalp, there is a huge variation in natural wave and the response to hair cosmetics. Although it is possible to give the hair a cosmetically favourable appearance through the use of cosmetic products, for good results in any hair treatment, it is essential to understand the mechanisms of the process. Important information, such as the composition and structure of the hair fibres, and the composition of products and techniques available for hair straightening, must be taken into account so that the straightening process can be designed appropriately, avoiding undesirable side effects for hair fibre and for health. This review aims to address the morphology, chemical composition and molecular structure of hair fibres, as well as the products and techniques used for chemical hair relaxing, their potential risk to hair fibre and to health and the legal aspects of their use. Resume L image personnelle, en ce qui concerne la beaute exterieure, a beaucoup attire l attention de l industrie cosmetique, et l esthetique capillaire est un leader de la consommation dans ce domaine. Il existe une grande variete de produits ciblant a la fois le traitement et la beaute du cheveu. Parmi eux, les defrisants se detachent par une forte Correspondence: Ana Luisa Miranda-Vilela, Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasilia/DF, Brazil. Tel.: ; fax: , s: and Luis Alexandre Muehlmann, Nanodynamics Consulting and Innovation, CLN 114, BL C, 42, Brasılia, Brazil. CEP Tel.: ; fax: ; demande de la part des consommateurs visant la beaute, l acceptation sociale et la facilite de l entretien quotidien des cheveux. Cependant, ce genre de traitement affecte la structure chimique de la keratine et de la fibre capillaire, suscitant des inquietudes en ce qui concerne la sante. En outre, la croissance des cheveux est un processus dynamique et cyclique, ou la duree des cycles de croissance depend non seulement de l endroit ou poussent les cheveux mais egalement de questions liees a l ^age de l individu, a ses habitudes alimentaires de m^eme qu a des facteurs hormonaux. Ainsi, bien que la fibre capillaire soit composee de cellules epidermiques mortes, quand celles-ci emergent du cuir chevelu, il existe une tres grande variation de l ondulation naturelle et de la reponse aux cosmetiques capillaires. Bien qu il soit possible, gr^ace a l utilisation de produits cosmetiques, de donner a la chevelure une belle apparence cosmetique, pour l obtention de bons resultats pour tous les traitements capillaires, il est essentiel de bien comprendre les mecanismes du processus. Des informations aussi importantes que la composition et la structure des fibres capillaires et la composition des produits et des techniques disponibles pour le lissage des cheveux doivent ^etre prises en compte afin que le processus de lissage soit defini de facßon appropriee, en evitant les effets secondaires indesirables pour la fibre capillaire et la sante. Cette analyse vise a traiter la morphologie, la composition chimique et la structure moleculaire de la fibre capillaire ainsi que les produits et les techniques utilises pour les relaxants capillaires chimiques, leur potentiel de risque pour la fibre capillaire et pour la sante ainsi que les aspects legaux de leur utilisation. Mots clés: analyses chimiques; croissance capillaire; traitement capillaire; tests de securite; lissage Introduction Attempts at beautification, mainly in women, especially involve the skin and its annexes [1]. Personal image, as it relates to external beauty, has been the target of investment in the beauty industry, and in this context, the branch of capillary aesthetics has attracted much attention from the cosmetic industry because it is considered a leader in consumption in this area [2]. As hair is one of the few physical features that can be easily modified to create a totally different style, be it in length, colour, or shape [3], there is a great diversity of products targeted for both the treatment and the beautification of hair; among them, hair relaxers and straighteners stand out. Generally, the term relaxer refers to products intended for the treatment of kinky hair, 2013 Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie 1

2 while straightener refers to products used for the treatment of curly hair in this work, the term straightener is used when referring to both products. The reasons for the use of hair straighteners include beauty, social acceptance and ease of daily hair maintenance [1]. However, these cosmetics affect only the hair shaft. As the newly developing hair will not be affected by these alterations, the new emerging hair will grow with its natural, original shape, and therefore, hair straightening needs to be repeated every 4 6 weeks [3]. Thus, the emphasis in this cosmetic treatment should be only on new growth, as repeated treatments can lead to hair breakage [3], and scalp and hair disorders [4], among others [1, 4 6]. Moreover, although the hair fibres are composed of dead epidermal cells, when they emerge from the scalp, there is huge variation in natural wave and the response to hair cosmetics [5]. Consequently, for obtaining good results, it is essential to understand the mechanism of the process and other important information such as the composition of natural hair fibres, the composition of products and techniques available for hair straightening. Thus, this review aims to address a comprehensive summary of the morphology, chemical composition and molecular structure of hair fibres, as well as the products and techniques used for chemical hair straightening, their potential risk to hair fibre and to health and legal aspects of their use. Structure of the hair fibre The hair is an appendage derived from the epidermis; it is a keratinized structure formed from the invagination of the epidermis into the dermis. From this invagination, small saccular structures called hair follicles originate [3, 7, 8]. Thus, it can be divided into two major parts: the hair follicle and the hair shaft [3]. The hair shaft extends from its root or bulb (located within the follicle), passing through the various layers of the epidermis, surpassing the stratum corneum and then continuing with a stem. Despite its shine, body, and texture, it is a dead structure (Fig. 1) [3, 5, 8]. Hair follicles are essential growth structures of hair, being strongly invaginated into the scalp tissue. At the base of each hair follicle, cells proliferate in upflow. The complex and intertwined processes of protein synthesis, structural alignment and keratinization transform the cytoplasm of these cells into a fibrous material known as hair [8, 9]. Thus, the primary component of hair fibre is keratin (about 65 95%), the remaining constituents being represented by other proteins, water, lipids (structural or free), pigments and trace elements [10 12]. Hair fibres (about lm in diameter) are not continuous in their entire length, but rather the result of the combination of compact groups of cells within the follicle, from which originate three basic morphological components: (i) the cuticle, which is the outermost region covering the core of the fibres; (ii) the cortex, which comprises most of the hair volume (75%) and is responsible for sustaining the hair shaft; and (iii) the medulla, which is the central area of the hair and is not always present [3, 10, 12 14]. The cuticle is composed primarily of keratin and displays a stepped structure with five to ten superimposed flat overlapping cells (scales) of lm thick, which are stacked like shingles on a roof and are oriented towards the distal (tip) end of the fibre. The outer surface of the cuticle s scale cells is coated by a thin membrane, the epicuticle, and each cuticle cell consists of three layers of protein: the A-layer, a resistant layer with high cystine content (>30%); the exocuticle, also rich in cystine (~15%); and the endocuticle, low in cystine content (~3%) (Fig. 2) [3, 8, 10, 14]. The cuticle encircles the cortex, which forms the most voluminous part of the hair fibre and is comprised of macrofibrils, long filaments oriented parallel to the axis of the fibre. Each macrofibril consists of keratin intermediate filaments (IF), also known as microfibrils, and the matrix, constituted by keratin-associated proteins (KAP) (Fig. 3). The cortical cell is spindle-shaped, about 100 lm long and generally 1-6 lm thick [8, 10, 11, 13, 14]. The medulla of human hair, if present, generally makes up only a small percentage of the mass of the whole hair and is believed to contribute negligibly to the mechanical properties of human hair fibres [11]. The hair appearance importantly depends on the health of the cuticle. When the cuticle is strong and healthy, hair appears to be strong and healthy. Intact and closed cuticle act as a protective shield against harmful environmental elements; when cuticle scales Figure 1 Structure of the human skin showing hair as an epidermal annex. Figure 2 Schematic cross-section of a hair fibre showing medulla, cortex and cuticle cell layers Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie

3 Figure 3 Schematic representation of the human hair fibre structure and its insertion into the scalp. (A) (B) Figure 4 Cuticles scales closed (A) and open (B). are open (raised), substances can be deposited in their structure (Fig. 4). Physical-chemical manipulation of the scales of the cuticle causes the appearance of hair to be changed, creating all kinds of different effects which can vary in softness, colour and even texture. Thus, from a cosmetic point of view, the cuticle is a very important component of the hair fibre [8]. The cortex also has a great cosmetic importance, as its optical properties strongly affect the colour and shine of hair fibre [15]. Keratins Keratins are a group of over 30 cytoskeletal proteins that, by possessing a diameter between 7 and 11 nm, are called intermediate filaments, that is, between microtubules (20 25 nm) and actin microfilaments (5 6 nm) [16]. They are high molecular weight polymers formed by long chains of amino acids linked together by different types of interactions. The keratin fibres consist of long molecular chains intertwined and firmly attached in different ways through covalent bonds (including disulphide bonds) and also weaker interactions such as hydrogen bonding, Coulomb electrostatic interactions and Van Der Waals, and when water is present, hydrophobic bonds [8 10]. Electrophoretic studies have divided hair keratins into two subfamilies: type I and type II. The type I keratins are acidic and have molecular weights varying from 40 to 48 kd, while those of type II are basic to neutral and have molecular weights varying from 58 to 65 kd [13]. Heid et al. (1986) [17] identified eight major hair keratins, four of each type. Other additional keratins were subsequent findings [18]. They are arranged in pairs of heterotypic chains of type I and type II and are distinguished from their epidermal counterparts by having a relatively high content of cysteine (7.6% vs. 2.9%, respectively) and a disulphide bond between two adjacent cysteines, forming a cystine that produces a stronger and more durable structure [19]. Thus, among numerous amino acids 2013 Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie 3

4 (A) (B) (C) Figure 5 Disulphide bond (A), coulomb interactions (B) and hydrogen bond (C) that hold different keratin protein together, giving strength to the hair fibre. that comprise the keratin of human hair, cystine is one of the most important. Each unit of cystine contains two amino acids of cysteine from different portions of the peptide chains which are interconnected by two sulphur atoms, forming a very strong bond known as a disulphide bond (Fig. 5) [11]. Intermolecular bonds, stability and strength of the hair fibre Disulphide bonds The high cysteine content of the protein comprising human hair results in a significant effect on the physical properties of the fibres [11]. Two adjacent cysteine residues are linked together, thus generating cystine, which forms a bridge between two proteins or between two portions of the same protein. In hair fibre, the high incidence of these cross-links (0.8 mm g 1 ), added to their susceptibility to oxidation or reduction, is the key for most chemical modifications of hair, which affect the physicochemical properties of the hair fibres [9]. [20]: all kinds of hair present common features of morphology, chemical composition (Table I) and molecular structure [20 24], but the shape of the hair varies greatly between different ethnic groups [9, 11, 20, 24 29]. Thus, categorizing different types of hair into three large groups African, Caucasian and Asian makes it easier to recognize the specific characteristics of each type of hair including colour, curling and other parameters [9]. Methods for categorizing hair based on its curvature, regardless of the ethnical origin, have been described elsewhere [29] and are useful for the standardization of technical terms in hair science. As shown in Table I, although there is a considerable variation within this set of data, the amino acid composition of hair fibres is always the same and the ranges of their concentration overlap and do not appear to vary greatly with ethnicity. Moreover, apart from their ethnicity, all hair fibres have a high content of cystine disulphide bonds, which contribute significantly to the stability of the fibre [9, 24]. What then does determine variations in the shape of hair? A definitive answer to this question has not yet been found, but appears to involve several factors, as explained below. Coulomb interactions The high content of acidic and basic side chains (1.6 mm g 1 ) gives rise to Coulomb interactions that are relatively stable in aqueous environments but easily broken by acids and alkalis [9]. Hydrogen bonds Although relatively weak and easily broken by water, hydrogen bonds are most numerous (about 4.6 mm g 1 ) in the hair fibres. Such interchain bonds between the amide groups along the polypeptide are essential for the stability of the a-helix structure of keratins [9]. Figure 5 illustrates these three main types of interchain interactions that occur between molecules of keratin of hair fibre. What determines the curl of the hair fibre? Evaluations of hair fail to demonstrate biochemical differences among ethnic groups, but some structural differences are seen Shape of the hair follicle The shape of the hair fibre is conferred during development, especially during keratinization [9], when hardening of the fibre occurs. Thus, it is logical to propose that the shape of the follicle in the zone of keratinization determines the shape of the hair fibre. This suggests that the growing fibre takes the shape of the mould, where hardening or keratinization occurs. Thus, if the follicle where the fibre is formed is curved in the area of keratinization, the emerging hair fibre will be highly wavy, but if the follicle is relatively straight, the emerging hair will be straight [24]. In this context, the shape of the cross-section of the hair and how it grows appear to be particularly related to the shape of the hair follicle and its position on the scalp (Table II) [9, 11, 25 27]. The cross-section of the hair is an ellipse that may tend more or less to a circle. Similarly, in the same way that a thin strip is wound more easily than a cylindrical rope, a hair with a flat and thin cross-section, like the African type, tends to be curled or crimped, with rings of up to a few millimetres diameter, while a hair with a thicker and cylindrical cross-section, like the Asian type, Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie

5 Table I Ranges of amino acid composition in the whole cosmetically unaltered hair fibre and of human hair from various ethnic origins. Data are expressed in micromoles per gram (lm g 1 ) of dry hair Amino acid Symbol Whole fibre* African Brown/Caucasian Asian Alanine Ala (A) Arginine Arg (R) Aspartic acid Asp (D) Cysteic acid Cya /2 Cystine ½ Cs Glutamic acid Glu (E) Glycine Gly (G) Histidine His (H) Isoleucine Ile (I) Leucine Leu (L) Lysine Lys (K) Methionine Met (M) Phenylalanine Phe (F) Proline Pro (P) Serine Ser (S) Threonine Thr (T) Tyrosine Tyr (Y) Valine Val (V) *The ranges of composition of amino acids were assembled from the results of Robbins and Kelly (1970) [21], Ward and Lundgren (1955) [22] and Clay et al. (1940) [23], obtained from Robbins (2002) [24]. Whole fibre results approximated by cortex analysis. Data obtained from Wofram (2003) [9]. Cysteines (Cys) are usually determined by quantification of their oxidation product, cysteic acid, generated by treatment with performic acid. Cystine (Cs) is a dimeric amino acid formed by the oxidation of two Cys residues that are covalently linked through a disulphide bond. It only forms after the protein chain has been synthesized and the protein starts to fold., Both Cys and Cs residues can be oxidized to cysteic acid. Table II Variation in growth and cross-section of the hair, according to ethnicity (11,26 28) Hair type Growth Shape Diameter (lm) Characteristic African 0.9 cm per month Flat oval As hair grows almost parallel to the scalp, it grows curled Caucasian 1.2 cm per month Almost oval Hair grows at an oblique angle to the scalp and is slightly curved Asian 1.3 cm per month Almost circular The mode as the follicle is implanted causes the hair to grow straight and perpendicular to the scalp tends to be straight. The Caucasoid hair, on the other hand, has a high variation in the cross-sectional shape between different individuals, which makes the shape of the fibres vary from wavy to very curly [25, 26]. Figure 6 shows a model that schematizes the relation between the curvature of the hair fibre and its cross-sectional shape. Bilateral distribution of the cortical cells Another possible factor contributing to the shape of hair considers the bilateral asymmetric structure of some keratinous fibres. Three types of cortical cells have been observed in the hair fibre: orthocortical (O), paracortical (P) and mesocortical (M) cells, and these are sometimes segregated into two distinct regions. Although it has been proposed in the late 1990s that, using phosphotungstic acid (PTA) staining methods described by Zhan (1980) [28], it should be revealing that the human orthocortex contains more non-keratin intermacrofibrillar matrix than the human paracortex [30, 31], it has been shown that orthocortical cells contain less matrix between intermediate filaments composed of keratin and a low sulphur content (~3%); paracortical cells are smaller in diameter, have smooth and rounded edges, and a sulphur content high (~5%); and mesocortical cells contain an intermediate level of cystine. If the opposite halves of the fibre grow at different rates or contract to different degrees during drying, a coiled fibre will emerge [24]. In curly hair, paracortical cells are present on the concave side of the capillary curve, while orthocortical cells are present on the opposite face, and mesocortical cells are absent. In straight hair, the cell distribution is concentric, with the orthocortical cells distributed along the whole perimeter of the fibre, around a layer of mesocortical cells surrounding paracortical cells (Fig. 7) [24]. Scientific data support the fact that differences in hair curvature reflect the distribution profile of the different cell types constituting the fibres and that fibre types vary from straight to heavily crimped with different intermediates [24], as exemplified in Fig Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie 5

6 Thibaut et al. (2007) observed that the smaller the interior angle of the fibre curvature, the fewer the mesocortical cells therein, while the location of the paracortical cells was more restricted to the concave face of the curve. This is independent of ethnic origin of the hair and is closely related to the curvature of the hair fibre [29]. Thus, the conclusion that can be drawn from this evidence is that an asymmetry in the composition of the hair fibre along its transverse axis determines its curvature. In the concave part of the hair fibre, which concentrates paracortical cells, the concentration of a subtype of acid keratin known as hha8 and of keratin-associated proteins (KAP) is high [32]. The latter are mainly those that form the matrix of the cortex and the proteins with a high content of cystine of the cuticle [24]. Products and techniques for hair straightening Figure 6 Schematic diagram of the relationship between the cross-section shapes of the hair fibre and the angle of its curvature. Figure 7 Representation of the distribution of orthocortical (O), mesocortical (M) and paracortical (P) cells in straight (left) and curly (right) hair fibres (Adapted from Robins, 2002 [24]). Straightening consists of temporary or permanent breaks in the chemical bonds that maintain the three-dimensional structure of keratin protein in its original rigid form, followed by straightening and mechanical fixing of the new form [33, 34]. It is an effective treatment for hair, which alters almost all aspects of the hair fibre structure to accomplish its objective: to confer on the hairs a durable and different configuration from that which is present in its native form [3, 8, 9]. Temporary straightening, using physicochemical techniques such as dryer, flat iron and the old hot comb, lasts only until the next wash. Hair has to be pre-wetted, to break the hydrogen bonds of keratin, thus permitting temporary opening of its original structure. With this, the strand straightens. Rapid drying with the hair dryer maintains the flat shape of the strand. The application of a hot iron shapes the strand (scales), providing the desired end-look. The strand gets smooth and shiny, to reflect more light [3, 33]. More permanent straightening of hair is affected by altering the disulphide bonds of keratin [33]. It can be achieved with alkaline creams containing up to 3.5% sodium hydroxide (lyebased straighteners), or else guanidine hydroxide, potassium hydroxide, or lithium hydroxide in place of sodium hydroxide (non-lye straighteners). Guanidine hydroxide needs to be acti- (A) (B) (C) Figure 8 Classification of hair samples: (A) straight, (B) wavy, (C) curly Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie

7 vated by adding 4 7% calcium hydroxide to produce calcium carbonate and guanidine hydroxide, the active agent [3, 35]. The aforementioned reagents cause lanthionization of hair and irreversible hair straightening. Chemical straightening can be also accomplished by ammonium or ethanolamine thioglycolate or bisulphite creams [33, 35, 36]. In the procedure with ammonium thioglycolate, the disulphide bonds are converted to sulphhydryl groups to allow the mechanical relaxation of the protein structure of hair fibres. After relaxation, free sulphhydryl groups are reoxidized (neutralized) to reform the disulphide bonds, thus looking in the desired conformation [37]. In principle, the treatment can be seen as a combination of reverse and gradual redirection of these disulphide bonds processes, with softening of the keratin, moulding into the desired shape and stabilizing the newly given geometry [9]. If mechanical straightening is carried out at a high temperature (use of flat iron, for example), it can occur with a much lower conversion of sulphhydryl groups to disulphide. If at these high temperatures the density of the sulphhydryl groups formed is low, returning to room temperature will be sufficient to stabilize the curvature of the hair fibres. This eliminates the need to reoxidize the sulphhydryl groups back to disulphide and results saving time and lesser degradation of fibre [37]. As mentioned previously, all chemical straighteners (ph ) use chemical reactions to change about 35% of cystine content of the hair to lanthionine, along with minor hydrolysis of peptide bonds [33, 35, 36]. When the hair is treated with hydroxide, disulphide bonds undergo rearrangement and cystine is ultimately converted to lanthionine. This monosulphide thio ether analogue of cystine (containing only one sulphur atom) helps stabilize the hair s straight configuration. The difference between a cystine and a lanthionine is the loss of one sulphur atom. The conversion of cystine to lanthionine weakens hair fibres, a loss of strength that can be measured readily through tensile measurements. As lanthionine is the main product of the reaction between alkali and cystine, these chemical straightening processes are known as lanthionization (Fig. 9) [34, 36, 38]. Besides the mentioned chemical straighteners, one of the most popular and dangerous is formaldehyde (solution 37%) and, more recently, glutaraldehyde. Formaldehyde, despite being a banned substance at any concentration for hair straightening [39], became frequent in this procedure, because besides being cheaper, it is a quick process and leaves the strands shiny [33]. Since 2005, the Brazilian Sanitary Surveillance Agency (ANVISA) declared itself against the use of that substance as a straightener, but it was only in 2009 that Resolution RDC 36, 17 June 2009 was published, which provides for the prohibition of exposure, sale and delivery for consumption of formaldehyde in drugstores, pharmacies, supermarkets, warehouses, emporia and convenience stores [40]. This was a measure to counter the use of formaldehyde and its derivatives as hair straighteners. It can cause serious damage to the tissues of the upper respiratory tract for the user and for the professional who applies the product and has carcinogenic and teratogenic potential [40 42]. When absorbed in the body by inhalation, and mainly by prolonged exposure, it presents a risk of developing cancers of the mouth, nostrils, lungs and blood to the head [42]. Formaldehyde can irritate the eyes and nose, cause allergic reactions of the skin, eyes and lungs and is a cancer hazard [43]. Glutaraldehyde is a saturated dialdehyde, slightly acidic in its natural state, and it has been used as a straightener since the prohibition of formaldehyde. It is a relatively common preservative in cosmetics and can be used in concentrations up to 0.2%. Its disinfectant activity is due to its reactivity with sulphhydryl, hydroxyl, carboxyl and amino groups, altering DNA, RNA and protein synthesis. Glutaraldehyde mutagenicity is extremely similar to that of formaldehyde. However, glutaraldehyde is six to eight times stronger than formaldehyde in producing cross-links in the DNA and about ten times more intense than formaldehyde in the production of tissue damage inside the nose after inhalation [33]. Due to the potential health hazard presented by preservativebased straighteners, since the onset of the progressive brushing craze, large companies have been trying to develop a product with a new active ingredient, not based on formaldehyde or any other type of preservative. In 2011, carbocysteine, whose chemical name is S-(carboxymethyl)-1-cysteine, was developed. It is a dibasic amino acid, with molecular weight of g mol 1 and molecular formula C 5 H 9 NO 4 S, which reduces hair volume by up to 90%, moisturizes and adds shine to hair [44]. The primary objective of this brushing technique is not to straighten the hair. This to seal the cuticle of the strands, reconstruct the hair fibre, reduce frizz and assist in growth, but, if done gradually, gives the effect of straightening [45]. Therefore, many hairdressers use this product in processes such as heat sealing, deep hydration, shielding and plastic hair. However, for the product to act, a process of rearrangement of cystine bonds is indispensable, which can be obtained with the use of the iron (high temperatures) or with glyoxylic acid [46]. Figure 9 Summarized overall reaction of lanthionine (Lan) formation through reactions between cystine with alkali (without intermediate details) (Adapted from Mack, 2009 [35]) Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie 7

8 Chemical straighteners and their potential damage to the hair fibre The common side effect of all chemical strengtheners is damage to the hair shaft [3, 35]. One of the damages that occur is the removal of the monomolecular layer of fatty acids covalently bound to the cuticle, including 18-methyl eicosanoic (18-MEA) acid. This hydrophobic layer retards water from wetting and penetrating the hair shaft and changing its physical properties. Removal of the fatty acid layer decreases the brightness of the hair, making it more susceptible to static electricity and frizzing induced by humidity. The second damaging event is the breaking and rearrangement of disulphide bonds, which preferentially affects the amino acids containing sulphur. In damaged hair that is not relaxed, there is a reduction of 21% cystine and a 50% decrease in methionine from the root to the tip of the hair shaft. These changes are magnified with chemical exposure [35]. Among the least harmful chemicals are the ammonium bisulphite creams and carbocysteine. The former contain a mixture of sulphide and disulphide, in variable proportions, depending on the ph of the lotion, but can only produce short-term smoothing [35], while the use of products with carbocysteine only serves to settle the hair and reduce the volume [46]. Health risks caused by chemical straightening Chemical relaxants have found wide use by individuals with wavy/ curly hair, both for the ease of care of relaxed hair and for the aesthetic aspect it provides. However, the number of reported side effects has health implications and draws attention to a higher emphasis on safer ways of application, as well as tougher legislation on these chemicals. The straightening process presents risks for users. The adverse results of repeated and regular professional applications of chemical hair straighteners for a period exceeding 1 year may include itching, burns and scars on the scalp, thinning and weakening of the hair shaft, discoloration and hair loss, apart from allergic reactions to chemicals [1, 4 6]. Legal aspects of the use of chemical hair straightening Although the definition of a cosmetic product may vary, even slightly, among the regions of the world, in general, the current regulatory framework for cosmetics in the U.S.A., Japan, Canada, Europe and Mercosur (Argentina, Brazil, Paraguay and Uruguay) has a broad definition of cosmetics, with safety ensured through control over ingredients in the form of positive lists, prohibited and restricted lists, specific requirements concerning safety testing and maintenance of data files on safety [47, 48]. The U.S.A., Japan and Canada also have a narrow definition, with few restrictions on the ingredients that can be used and the type of safety testing to be undertaken as determined by manufacturers. In the U.S.A., products can be categorized as either cosmetics or drugs and are therefore subject to both sets of regulations. Japan has an additional product category of quasi-drugs whose regulation is less rigorous than that of drugs but still requires pre-market approval and registration of ingredients. The Association of Southeast Asian Nations (ASEAN), Mercosur and the Comunidad Andina (Andean Pact) regions have used the European model in drafting their own cosmetic regulations, which are closer to the Japanese model but without the category of quasi-drugs [48]. Nevertheless, in Europe, the cosmetic field distinguishes itself from other sectors through some challenging particularities, nearly all driven by European cosmetic legislation, where in the first instance, the term risk assessment is replaced by safety evaluation, because a cosmetic product is a priori considered to be safe [49]. In Brazil, the legislation of Mercosur was internalized by ANVI- SA, through specific Resolutions and Ordinances pertaining to the verification of compliance with good manufacturing practices and control of industrial establishments for the manufacture of toiletries, cosmetics and perfumes; those dealing with the definition of cosmetic products, requirements for registration, nomenclature for ingredients; handbook of good manufacturing practices for cosmetics; microbiological control parameters, among others, including those related to positive lists, prohibited and restricted lists; and specific requirements concerning safety testing and maintenance of data files on safety [47]. For hair straightening, for example, as previously mentioned, ANVISA does not register hair straighteners based on formaldehyde, as to achieve straightening, this product has to be used in concentrations of 20 30%, which is totally banned [33]. The sanitary legislation permits the use of formaldehyde and glutaraldehyde in cosmetics only with the function of preserving (with a maximum limit of 0.2% and 0.1%, respectively, according to Resolution RDC No 162 of September 11, 2001) or as nail hardener at a maximum limit of 5% (Resolution RDC No 215 of July 25, 2005) [33, 40, 50, 51]. On the other hand, according to the United States Department of Labor s Occupational Safety and Health Administration (OSHA), hazards associated with formaldehyde must be listed if it is present in the product at 0.1% or more (as a gas or in solution) or if the product releases formaldehyde into the air above 0.1 parts per million [43]. The risk of this substance being misapplied increases as concentrations and frequency of use rise and occurs through gas inhalation and by skin contact, being dangerous both for professionals who apply the product and for users [33]. There are other substances registered in ANVISA which can be used for straightening hair. These include ammonium thioglycolate, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide and guanidine carbonate, but subject to restrictions and established conditions, according to Ordinance No 71 of May 29, 1996 and its updates [47, 50, 51]. Any straightener can burn the scalp if used incorrectly, because lye found in many hair relaxants can burn the skin and even those without lye still need to be safe and used correctly [52]. Thus, according to the United States Federal Food, Drug, and Cosmetic Act (FD&C Act), one of the two most important laws pertaining to cosmetics marketed in the United States, the caution This product contains ingredients which may cause skin irritation on certain individuals and a preliminary test according to accompanying directions should first be made, must be placed on the product label displayed, for the cosmetic is not deemed to be adulterated [53]. Conclusions Any chemical process of cosmetic treatment for hair straightening affects the chemical structure of the keratin fibres, because these processes target links that provide stability for the fibre. Although hair fibres are composed of dead epidermal cells, when they emerge from the scalp, there is wide variation in their natural wave and their response to hair cosmetics. Moreover, the development of hair is a dynamic and cyclic process, where the duration of growth cycles depends not only on where hair grows, but also on issues Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie

9 such as the individual s age, dietary habits and hormonal factors. Thus, although it is possible to give hair a cosmetically favourable appearance through the use of cosmetic products, it is necessary to take into account these issues and understand first the morphology of hair so that treatment can be done appropriately, avoiding the undesirable side effects mentioned above. Also, it is advisable to be familiar with the current regulatory framework for cosmetics to know whether the product to be applied is within the norms of current legislation in the country, which serve to protect the client from adverse health effects. Acknowledgements The authors gratefully acknowledge the Brazilian National Council for Technological and Scientific Development (CNPq) for scholarships for the Training Program of Human Resources in Strategic Areas (RHAE) Researcher in Company, for Ana Luisa Miranda- Vilela, as well as CNPq and the company Beleza Natural (Natural Beauty) for financial support for Nanodynamics. References 1. Olasode, O.A. Chemical hair relaxation and adverse outcomes among Negroid women in South West Nigeria. J. Pak. Assoc. Dermatol. 19, (2009). 2. Rodrigues, G., Rodrigues, M. and Francßa, A. Analise das diferencßas de composicß~ao e modo de aplicacß~ao de produtos capilares hen^e e henna. Available at: Giuvane%20Bezerra%20Rodrigues%20e% 20Maria%20Sania%20Barbara%20Stefanello.pdf, accessed 8 October Bolduc, C. and Shapiro, J. Hair care products: waving, straightening, conditioning, and coloring. Clin. Dermatol. 19, (2001). 4. Rucker Wright, D., Gathers, R., Kapke, A., Johnson, D. and Joseph, C.L. Hair care practices and their association with scalp and hair disorders in African American girls. J. Am. Acad. Dermatol. 64, (2011). 5. Khumalo, N. Hair fashion trends and formaldehyde health risks. S. Afr. Med. J. 101, 872 (2011). 6. Khumalo, N.P., Stone, J., Gumedze, F., McGrath, E., Ngwanya, M.R. and de Berker, D. Relaxers damage hair: evidence from amino acid analysis. J. Am. Acad. Dermatol. 62, (2010). 7. Widelitz, R.B. Wnt signaling in skin organogenesis. Organogenesis 4, (2008). 8. Rieger, M.M., ed. Harry s Cosmetology. 8th edn, Chemical Publishing Co Inc, New York (2000). 9. Wolfram, L.J. Human hair: a unique physicochemical composite. J. Am. Acad. Dermatol. 48, S106 S114 (2003). 10. Araujo, R., Fernandes, M., Cavaco-Paulo, A. and Gomes, A. Biology of human hair: know your hair to control it. In: Biofunctionalization of Polymers and their Applications (Nyanhongo, G.S., Steiner, W. and G ubitz, G., eds), pp Springer-Verlag, Berlin/Heidelberg (2010). 11. Bhushan, B. Introduction: human hair, skin, and hair care products. In: Biophysics of Human Hair: Biological and Medical Physics, Biomedical Engineering (Bhushan, B., ed), pp Springer-Verlag, Berlin/Heidelberg (2010). 12. Velasco, M.V.R., Dias, T.C.S., Freitas, A.Z., Vieira Junior, N.D., Pinto, C.A.S.O., Kaneko, T.M. and Baby, A.R. Hair fiber characteristics and methods to evaluate hair physical and mechanical properties. Braz. J. Pharm. Sci. 45, (2009). 13. Lai-Cheong, J.E. and McGrath, J.A. Structure and function of skin, hair and nails. Medicine 37, (2009). 14. Bhushan, B. and Chen, N. AFM studies of environmental effects on nanomechanical properties and cellular structure of human hair. Ultramicroscopy 106, (2006). 15. Kharin, A., Varghese, B., Verhagen, R. and Uzunbajakava, N. Optical properties of the medulla and the cortex of human scalp hair. J. Biomed. Opt. 14, 1 7 (2009). 16. Keratin 31; KRT31 [database on the Internet]. Available at: accessed 8 October Heid, H.W., Werner, E. and Franke, W.W. The complement of native alphakeratin polypeptides of hair-forming cells: a subset of eight polypeptides that differ from epithelial cytokeratins. Differentiation 32, (1986). 18. Langbein, L., Rogers, M.A., Winter, H., Praetzel, S., Beckhaus, U., Rackwitz, H.-R. and Schweizer, J. The catalog of human hair keratins. J. Biol. Chem. 274, (1999). 19. Yu, J., Yu, D.W., Checkla, D.M., Freedberg, I.M. and Bertolino, A.P. Human hair keratins. J. Invest. Dermatol. 101, 56S 59S (1993). 20. McMichael, A.J. Ethnic hair update: past and present. J. Am. Acad. Dermatol. 48(Suppl. 6), S127 S133 (2003). 21. Robbins, C.R. and Kelly, C.H. Amino acid composition of human hair. Text. Res. J. 40, (1970). 22. Ward, W.H. and Lundgren, H.P. The formation, composition, and properties of the keratins. Adv. Protein Chem. 9, (1954). 23. Clay, R.C., Cook, K. and Routh, J.I. Studies in the composition of human hair. J. Am. Chem. Soc. 62, (1940). 24. Robbins, C.R. Chemical and Physical Behavior of Human Hair, 4th edn. Springer-Verlag, New York (2002). 25. Draelos, D. The biology of hair care. Dermatol. Clin. 18, (2000). 26. Carvalho, A., Egıdio, C., Nakaya, H. et al. Bioquımica da Beleza. Available at: accessed 11 April Osorio, F. and Tosti, A. Hair weathering, part 1: hair structure and pathogenesis. Cosmet. Dermatol. 24, (2011). 28. Zahn, H. Wool is not keratin only. Proc. 6th Int. Wool Text. Res. Conf. 1, 1 45 (1980). 29. Loussouarn, G., Garcel, A., Lozano, I. et al. Worldwide diversity of hair curliness: a new method of assessment. Int. J. Dermat. 46 (Suppl. 1), 2 6 (2007). 30. Jolles, P., Zahn, H. and H ocker, H. Formation and Structure of Human Hair. Birkh auser, Berlin (1997). 31. Swift, J.A. Fundamentals of Human Hair Science. Micelle Press, Dorset, (1997). 32. Thibaut, S., Barbarat, P., Leroy, F. and Bernard, B.A. Human hair keratin network and curvature. Int. J. Dermatol. 46, 7 10 (2007). 33. Abraham, L.S., Moreira, A.M., de Moura, L.H., Gavazzoni, M.F.R. and Addor, F.A.S. Tratamentos esteticos e cuidados dos cabelos: uma vis~ao medica (parte 2). Surg. Cosmet. Dermatol. 1, (2009). 34. Bouillon, C. and Wilkinson, J. The Science of Hair Care, 2nd edn. Taylor & Francis Group, New York (2005). 35. Draelos, Z.D. Commentary: healthy hair and protein loss. J. Am. Acad. Dermatol. 62, (2010). 36. Wong, M., Wis-Surel, G. and Epps, J. Mechanism of hair straightening. J. Soc. Cosmet. Chem. 45, (1994). 37. Feughelman, M. A note on the permanent setting of human hair. J. Soc. Cosmet. Chem. 41, (1990). 38. Mack, S. Mad Science Search Results: What is a Chemical Equation for Hair Relaxers. Available at: Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie 9

10 archives/ / ch.r.html, accessed 27 March Santos, M.B., Silva, A.B., Silva, F.S. and Silva, J.M. Uso do formol como alisante capilar. 51º Congresso Brasileiro de Quımica. S~ao Luis/MA, CBQ, Available at: org.br/cbq/2011/trabalhos/14/ htm, accessed 20 March Ag^encia Nacional de Vigil^ancia Sanitaria (Anvisa). RDC No 36, de 17 de junho de Available at: br/divulga/noticias/2008/040608_1_rdc36. pdf, accessed 12 April Abraham, L.S. ANVISA proıbe o uso de formol e glutaraldeıdo como alisantes. Sociedade Brasileira de Dermatologia - Regional Rio de Janeiro (SBDRJ). Available at: accessed 3 April Ag^encia Nacional de Vigil^ancia Sanitaria (Anvisa). Anvisa alerta sobre o uso de formol em alisamento capilar Brasılia. Available at: 2007/ htm, accessed 3 April Occupational Safety and Health Administration (OSHA). Formaldehyde. Available at: Facts/formaldehyde-factsheet.pdf, accessed 3 April MedicinaNet. Carbocisteına Gotas. Available at: 8052/carbocisteina_gotas.htm, Accessed 3 April Beleza, G.N.T. Escova de Carbocisteına. Available at: Escova-de-Carbocisteina.shtml, accessed 3 April Cosmetologia in radice. Carbocisteına e acido glioxılico. Available at: accessed 3 April Ag^encia Nacional de Vigil^ancia Sanitaria (Anvisa). Legislacß~ao Mercosul. Available at: mercosul.htm, accessed 9 April Pellegrini, M., Marchei, E., Pacifici, R., Rotolo, M.C. and Pichini, S. Advances in the analysis of non-allowed pharmacologically active substances in cosmetic products. J. Pharm. Biomed. Anal. 55, (2011). 49. Pauwels, M. and Rogiers, V. Human health safety evaluation of cosmetics in the EU: a legally imposed challenge to science. Toxicol. Appl. Pharmacol. 243, (2010). 50. Ag^encia Nacional de Vigil^ancia Sanitaria (Anvisa). RDC No 215, de 25 de julho de Available at: br/wps/content/anvisa+portal/anvisa/inicio/cosmeticos/assuntos+de+interesse/legislacoes/notificacao, accessed 9 April Ag^encia Nacional de Vigil^ancia Sanitaria (Anvisa). RDC No 162 de 11 de setembro de Available at: br/wps/wcm/connect/1f8f29004aee443bb 774bfa337abae9d/Resolu%C3%A7%C3% A3o+RDC+n%C2%BA+162,+de+11 + de+ setembro+de+2001.pdf?mod=ajperes, accessed 12 April U.S. Food and Drug Administration (FDA). Hair Dye and Hair Relaxers. Available at: accessed 9 April U.S. Federal Food, Drug, and Cosmetic Act (FD&C Act). Available at: gov/regulatoryinformation/legislation/federalfooddrugandcosmeticactfdcact, accessed 9 April Society of Cosmetic Scientists and the Societe Francßaise de Cosmetologie

Pipe Cleaner Proteins. Essential question: How does the structure of proteins relate to their function in the cell?

Pipe Cleaner Proteins. Essential question: How does the structure of proteins relate to their function in the cell? Pipe Cleaner Proteins GPS: SB1 Students will analyze the nature of the relationships between structures and functions in living cells. Essential question: How does the structure of proteins relate to their

More information

Inside Hair: A Closer Look at Color and Shape

Inside Hair: A Closer Look at Color and Shape Inside Hair: A Closer Look at Color and Shape For the past decade women and men alike have had chemical treatments preformed on their hair. Consumers spend millions of dollars on hair care products such

More information

IV. -Amino Acids: carboxyl and amino groups bonded to -Carbon. V. Polypeptides and Proteins

IV. -Amino Acids: carboxyl and amino groups bonded to -Carbon. V. Polypeptides and Proteins IV. -Amino Acids: carboxyl and amino groups bonded to -Carbon A. Acid/Base properties 1. carboxyl group is proton donor! weak acid 2. amino group is proton acceptor! weak base 3. At physiological ph: H

More information

P R O F E S S I O N A L

P R O F E S S I O N A L Positioning: Liquid Keratin Professional Restorative Smoothing Treatment is an exclusive new system developed to promote the smoothing and relaxing of waves while repairing damage caused from other chemical

More information

A. A peptide with 12 amino acids has the following amino acid composition: 2 Met, 1 Tyr, 1 Trp, 2 Glu, 1 Lys, 1 Arg, 1 Thr, 1 Asn, 1 Ile, 1 Cys

A. A peptide with 12 amino acids has the following amino acid composition: 2 Met, 1 Tyr, 1 Trp, 2 Glu, 1 Lys, 1 Arg, 1 Thr, 1 Asn, 1 Ile, 1 Cys Questions- Proteins & Enzymes A. A peptide with 12 amino acids has the following amino acid composition: 2 Met, 1 Tyr, 1 Trp, 2 Glu, 1 Lys, 1 Arg, 1 Thr, 1 Asn, 1 Ile, 1 Cys Reaction of the intact peptide

More information

Part A: Amino Acids and Peptides (Is the peptide IAG the same as the peptide GAI?)

Part A: Amino Acids and Peptides (Is the peptide IAG the same as the peptide GAI?) ChemActivity 46 Amino Acids, Polypeptides and Proteins 1 ChemActivity 46 Part A: Amino Acids and Peptides (Is the peptide IAG the same as the peptide GAI?) Model 1: The 20 Amino Acids at Biological p See

More information

Advanced Medicinal & Pharmaceutical Chemistry CHEM 5412 Dept. of Chemistry, TAMUK

Advanced Medicinal & Pharmaceutical Chemistry CHEM 5412 Dept. of Chemistry, TAMUK Advanced Medicinal & Pharmaceutical Chemistry CHEM 5412 Dept. of Chemistry, TAMUK Dai Lu, Ph.D. dlu@tamhsc.edu Tel: 361-221-0745 Office: RCOP, Room 307 Drug Discovery and Development Drug Molecules Medicinal

More information

Technical bulletin: Keratin Smoothing Treatment

Technical bulletin: Keratin Smoothing Treatment Technical bulletin: Keratin Treatment Easy 5-step process with a spectacular result. Essential parts of native keratin New level of conditioning Result lasts for 2 to 3 months. 100% Formaldehyde Free!

More information

Recap. Lecture 2. Protein conformation. Proteins. 8 types of protein function 10/21/10. Proteins.. > 50% dry weight of a cell

Recap. Lecture 2. Protein conformation. Proteins. 8 types of protein function 10/21/10. Proteins.. > 50% dry weight of a cell Lecture 2 Protein conformation ecap Proteins.. > 50% dry weight of a cell ell s building blocks and molecular tools. More important than genes A large variety of functions http://www.tcd.ie/biochemistry/courses/jf_lectures.php

More information

Amino Acids, Peptides, Proteins

Amino Acids, Peptides, Proteins Amino Acids, Peptides, Proteins Functions of proteins: Enzymes Transport and Storage Motion, muscle contraction Hormones Mechanical support Immune protection (Antibodies) Generate and transmit nerve impulses

More information

Built from 20 kinds of amino acids

Built from 20 kinds of amino acids Built from 20 kinds of amino acids Each Protein has a three dimensional structure. Majority of proteins are compact. Highly convoluted molecules. Proteins are folded polypeptides. There are four levels

More information

BOC334 (Proteomics) Practical 1. Calculating the charge of proteins

BOC334 (Proteomics) Practical 1. Calculating the charge of proteins BC334 (Proteomics) Practical 1 Calculating the charge of proteins Aliphatic amino acids (VAGLIP) N H 2 H Glycine, Gly, G no charge Hydrophobicity = 0.67 MW 57Da pk a CH = 2.35 pk a NH 2 = 9.6 pi=5.97 CH

More information

Shu-Ping Lin, Ph.D. E-mail: splin@dragon.nchu.edu.tw

Shu-Ping Lin, Ph.D. E-mail: splin@dragon.nchu.edu.tw Amino Acids & Proteins Shu-Ping Lin, Ph.D. Institute te of Biomedical Engineering ing E-mail: splin@dragon.nchu.edu.tw Website: http://web.nchu.edu.tw/pweb/users/splin/ edu tw/pweb/users/splin/ Date: 10.13.2010

More information

Protein Physics. A. V. Finkelstein & O. B. Ptitsyn LECTURE 1

Protein Physics. A. V. Finkelstein & O. B. Ptitsyn LECTURE 1 Protein Physics A. V. Finkelstein & O. B. Ptitsyn LECTURE 1 PROTEINS Functions in a Cell MOLECULAR MACHINES BUILDING BLOCKS of a CELL ARMS of a CELL ENZYMES - enzymatic catalysis of biochemical reactions

More information

18.2 Protein Structure and Function: An Overview

18.2 Protein Structure and Function: An Overview 18.2 Protein Structure and Function: An Overview Protein: A large biological molecule made of many amino acids linked together through peptide bonds. Alpha-amino acid: Compound with an amino group bonded

More information

2007 7.013 Problem Set 1 KEY

2007 7.013 Problem Set 1 KEY 2007 7.013 Problem Set 1 KEY Due before 5 PM on FRIDAY, February 16, 2007. Turn answers in to the box outside of 68-120. PLEASE WRITE YOUR ANSWERS ON THIS PRINTOUT. 1. Where in a eukaryotic cell do you

More information

Carbohydrates, proteins and lipids

Carbohydrates, proteins and lipids Carbohydrates, proteins and lipids Chapter 3 MACROMOLECULES Macromolecules: polymers with molecular weights >1,000 Functional groups THE FOUR MACROMOLECULES IN LIFE Molecules in living organisms: proteins,

More information

Paper: 6 Chemistry 2.130 University I Chemistry: Models Page: 2 of 7. 4. Which of the following weak acids would make the best buffer at ph = 5.0?

Paper: 6 Chemistry 2.130 University I Chemistry: Models Page: 2 of 7. 4. Which of the following weak acids would make the best buffer at ph = 5.0? Paper: 6 Chemistry 2.130 University I Chemistry: Models Page: 2 of 7 4. Which of the following weak acids would make the best buffer at ph = 5.0? A) Acetic acid (Ka = 1.74 x 10-5 ) B) H 2 PO - 4 (Ka =

More information

Before you know about your future see your past before improving your future hair see what has been and is the state of your hair now Ravi Bhanot

Before you know about your future see your past before improving your future hair see what has been and is the state of your hair now Ravi Bhanot Chapter 1 All you need to know about hair almost Before you know about your future see your past before improving your future hair see what has been and is the state of your hair now Ravi Bhanot Typically

More information

Amino Acids. Amino acids are the building blocks of proteins. All AA s have the same basic structure: Side Chain. Alpha Carbon. Carboxyl. Group.

Amino Acids. Amino acids are the building blocks of proteins. All AA s have the same basic structure: Side Chain. Alpha Carbon. Carboxyl. Group. Protein Structure Amino Acids Amino acids are the building blocks of proteins. All AA s have the same basic structure: Side Chain Alpha Carbon Amino Group Carboxyl Group Amino Acid Properties There are

More information

The Organic Chemistry of Amino Acids, Peptides, and Proteins

The Organic Chemistry of Amino Acids, Peptides, and Proteins Essential rganic Chemistry Chapter 16 The rganic Chemistry of Amino Acids, Peptides, and Proteins Amino Acids a-amino carboxylic acids. The building blocks from which proteins are made. H 2 N C 2 H Note:

More information

PROPERTIES OF THE HAIR AND SCALP

PROPERTIES OF THE HAIR AND SCALP PROPERTIES OF THE HAIR AND SCALP 1. The scientific study of hair, its diseases and care is called: a. dermatology c. biology b. trichology d. cosmetology 2. The two parts of a mature hair strand are the

More information

H H N - C - C 2 R. Three possible forms (not counting R group) depending on ph

H H N - C - C 2 R. Three possible forms (not counting R group) depending on ph Amino acids - 0 common amino acids there are others found naturally but much less frequently - Common structure for amino acid - C, -N, and functional groups all attached to the alpha carbon N - C - C

More information

Hair & Fiber. (Unit 5)

Hair & Fiber. (Unit 5) 37 Hair & Fiber (Unit 5) Morphology of Hair Hair is encountered as physical evidence in a wide variety of crimes. A review of the forensic aspects of hair examination must start with the observation that

More information

The chemistry of insulin

The chemistry of insulin FREDERICK S ANGER The chemistry of insulin Nobel Lecture, December 11, 1958 It is great pleasure and privilege for me to give an account of my work on protein structure and I am deeply sensitive of the

More information

Lecture Overview. Hydrogen Bonds. Special Properties of Water Molecules. Universal Solvent. ph Scale Illustrated. special properties of water

Lecture Overview. Hydrogen Bonds. Special Properties of Water Molecules. Universal Solvent. ph Scale Illustrated. special properties of water Lecture Overview special properties of water > water as a solvent > ph molecules of the cell > properties of carbon > carbohydrates > lipids > proteins > nucleic acids Hydrogen Bonds polarity of water

More information

Peptide bonds: resonance structure. Properties of proteins: Peptide bonds and side chains. Dihedral angles. Peptide bond. Protein physics, Lecture 5

Peptide bonds: resonance structure. Properties of proteins: Peptide bonds and side chains. Dihedral angles. Peptide bond. Protein physics, Lecture 5 Protein physics, Lecture 5 Peptide bonds: resonance structure Properties of proteins: Peptide bonds and side chains Proteins are linear polymers However, the peptide binds and side chains restrict conformational

More information

Helices From Readily in Biological Structures

Helices From Readily in Biological Structures The α Helix and the β Sheet Are Common Folding Patterns Although the overall conformation each protein is unique, there are only two different folding patterns are present in all proteins, which are α

More information

CHAPTER 4 CHARACTERIZATION OF CHICKEN FEATHER FIBRE (CFF)

CHAPTER 4 CHARACTERIZATION OF CHICKEN FEATHER FIBRE (CFF) 66 CHAPTER 4 CHARACTERIZATION OF CHICKEN FEATHER FIBRE (CFF) 4.1 INTRODUCTION It is possible to find in Nature an almost unlimited source of high performance materials which remain to be critically studied

More information

Biochemistry - I. Prof. S. Dasgupta Department of Chemistry Indian Institute of Technology, Kharagpur Lecture-11 Enzyme Mechanisms II

Biochemistry - I. Prof. S. Dasgupta Department of Chemistry Indian Institute of Technology, Kharagpur Lecture-11 Enzyme Mechanisms II Biochemistry - I Prof. S. Dasgupta Department of Chemistry Indian Institute of Technology, Kharagpur Lecture-11 Enzyme Mechanisms II In the last class we studied the enzyme mechanisms of ribonuclease A

More information

4. Which carbohydrate would you find as part of a molecule of RNA? a. Galactose b. Deoxyribose c. Ribose d. Glucose

4. Which carbohydrate would you find as part of a molecule of RNA? a. Galactose b. Deoxyribose c. Ribose d. Glucose 1. How is a polymer formed from multiple monomers? a. From the growth of the chain of carbon atoms b. By the removal of an OH group and a hydrogen atom c. By the addition of an OH group and a hydrogen

More information

Please visit your examination provider s website for the most current bulletin prior to testing. IMPORTANT INSTRUCTIONS

Please visit your examination provider s website for the most current bulletin prior to testing. IMPORTANT INSTRUCTIONS NATIONAL BARBER THEORY EXAMINATION CANDIDATE INFORMATION BULLETIN Please visit your examination provider s website for the most current bulletin prior to testing. The National Barber Theory Examination

More information

HAIR THERAPY KERATIN TREATMENT INSTRUCTION MANUAL THE SYSTEM THAT MAKES CLIENTS DREAMS COME TRUE!

HAIR THERAPY KERATIN TREATMENT INSTRUCTION MANUAL THE SYSTEM THAT MAKES CLIENTS DREAMS COME TRUE! INSTRUCTION MANUAL THE SYSTEM THAT MAKES CLIENTS DREAMS COME TRUE! Keeping one s hair healthy is one of the challenges faced by the modern woman. We are constantly surrounded by elements that are harmful

More information

Biochemistry 2000 Sample Question Proteins. (1) Identify the secondary structure described in each of the following statements:

Biochemistry 2000 Sample Question Proteins. (1) Identify the secondary structure described in each of the following statements: (1) Identify the secondary structure described in each of the following statements: a. A coiled peptide chain held in place by hydrogen bonding between peptide bonds in the same chain b. A structure that

More information

Biological Molecules

Biological Molecules Biological Molecules I won t lie. This is probably the most boring topic you have ever done in any science. It s pretty much as simple as this: learn the material deal with it. Enjoy don t say I didn t

More information

Amino Acids and Proteins

Amino Acids and Proteins Amino Acids and Proteins Proteins are composed of amino acids. There are 20 amino acids commonly found in proteins. All have: N2 C α R COO Amino acids at neutral p are dipolar ions (zwitterions) because

More information

CHEM 107. Hair handout. Basic Structure of Hair. 3-22-05 and 3-24-05

CHEM 107. Hair handout. Basic Structure of Hair. 3-22-05 and 3-24-05 CHEM 107 Hair handout. 3-22-05 and 3-24-05 Basic Structure of Hair A hair can be defined as a slender, thread-like outgrowth from a follicle in the skin of mammals. Composed mainly of keratin, it has three

More information

Separation of Amino Acids by Paper Chromatography

Separation of Amino Acids by Paper Chromatography Separation of Amino Acids by Paper Chromatography Chromatography is a common technique for separating chemical substances. The prefix chroma, which suggests color, comes from the fact that some of the

More information

INTRODUCTION TO PROTEIN STRUCTURE

INTRODUCTION TO PROTEIN STRUCTURE Name Class: Partner, if any: INTRODUCTION TO PROTEIN STRUCTURE PRIMARY STRUCTURE: 1. Write the complete structural formula of the tripeptide shown (frame 10). Circle and label the three sidechains which

More information

CSC 2427: Algorithms for Molecular Biology Spring 2006. Lecture 16 March 10

CSC 2427: Algorithms for Molecular Biology Spring 2006. Lecture 16 March 10 CSC 2427: Algorithms for Molecular Biology Spring 2006 Lecture 16 March 10 Lecturer: Michael Brudno Scribe: Jim Huang 16.1 Overview of proteins Proteins are long chains of amino acids (AA) which are produced

More information

Preliminary MFM Quiz

Preliminary MFM Quiz Preliminary MFM Quiz 1. The major carrier of chemical energy in all cells is: A) adenosine monophosphate B) adenosine diphosphate C) adenosine trisphosphate D) guanosine trisphosphate E) carbamoyl phosphate

More information

There are some differences between hair and growth rates across different ethnic groups.

There are some differences between hair and growth rates across different ethnic groups. Basic Facts about Hair The cells that produce our hair have the fastest growth rate of all cells in the human body. Each hair goes through an independent cycle of growth, which lasts on average 5 years.

More information

Ionization of amino acids

Ionization of amino acids Amino Acids 20 common amino acids there are others found naturally but much less frequently Common structure for amino acid COOH, -NH 2, H and R functional groups all attached to the a carbon Ionization

More information

Disaccharides consist of two monosaccharide monomers covalently linked by a glycosidic bond. They function in sugar transport.

Disaccharides consist of two monosaccharide monomers covalently linked by a glycosidic bond. They function in sugar transport. 1. The fundamental life processes of plants and animals depend on a variety of chemical reactions that occur in specialized areas of the organism s cells. As a basis for understanding this concept: 1.

More information

Amino Acids, Proteins, and Enzymes. Primary and Secondary Structure Tertiary and Quaternary Structure Protein Hydrolysis and Denaturation

Amino Acids, Proteins, and Enzymes. Primary and Secondary Structure Tertiary and Quaternary Structure Protein Hydrolysis and Denaturation Amino Acids, Proteins, and Enzymes Primary and Secondary Structure Tertiary and Quaternary Structure Protein Hydrolysis and Denaturation 1 Primary Structure of Proteins H 3 N The particular sequence of

More information

Hair Chemistry. Chapter 1. Hair Relaxers Science, Design, and Application www.alluredbooks.com

Hair Chemistry. Chapter 1. Hair Relaxers Science, Design, and Application www.alluredbooks.com Hair Relaxers Science, Design, and Application www.alluredbooks.com Chapter 1 Hair Chemistry We all know that the hair on our head is dead, but underneath the scalp, within the hair follicle, is a surprisingly

More information

Consultation Tools. The Educational Tool Kit. Porosity: The hair s ability to absorb moisture and liquids.

Consultation Tools. The Educational Tool Kit. Porosity: The hair s ability to absorb moisture and liquids. Consultation Tools The Educational Tool Kit. Porosity: The hair s ability to absorb moisture and liquids. To explain porosity in the hair you need the following items: Wax paper, Construction paper, Paper

More information

BASIC CONCEPTS OF HAIR PHYSIOLOGY AND COSMETIC HAIR DYES

BASIC CONCEPTS OF HAIR PHYSIOLOGY AND COSMETIC HAIR DYES Staple here TECHNICAL MANUAL BASIC CONCEPTS OF HAIR PHYSIOLOGY AND COSMETIC HAIR DYES COVER PAGE MACRO-STRUCTURE OF THE HAIR The hair is formed by the shaft and the piliferous bulb. The visible part of

More information

IT S BETTER ABOUT THE ANEVOLVE CONTROL ZERO STRAIGHTENING SYSTEM IT S NOT BRAZILIAN... QUESTIONS AND ANSWERS. a s s o c i a t i o n o f.

IT S BETTER ABOUT THE ANEVOLVE CONTROL ZERO STRAIGHTENING SYSTEM IT S NOT BRAZILIAN... QUESTIONS AND ANSWERS. a s s o c i a t i o n o f. IT S NOT BRAZILIAN... IT S BETTER QUESTIONS AND ANSWERS ABOUT THE ANEVOLVE CONTROL ZERO STRAIGHTENING SYSTEM Copyright 2011 Anevolve Corporation a s s o c i a t i o n o f SECURITY GUARDS 1121 Holland Drive

More information

GELITA Sol C for Radiant Beauty. Comprises high-performance natural collagen peptides Provides smooth and wrinkle-free skin Repairs and protects hair

GELITA Sol C for Radiant Beauty. Comprises high-performance natural collagen peptides Provides smooth and wrinkle-free skin Repairs and protects hair GELITA Sol C for Radiant Beauty Comprises high-performance natural collagen peptides Provides smooth and wrinkle-free skin Repairs and protects hair Women are convinced of the benefits of GELITA Sol C

More information

Amino Acids - Building Blocks of Proteins

Amino Acids - Building Blocks of Proteins Amino Acids - Building Blocks of Proteins Introduction Proteins are more than an important part of your diet. Proteins are complex molecular machines that are involved in nearly all of your cellular functions.

More information

MCAT Organic Chemistry - Problem Drill 23: Amino Acids, Peptides and Proteins

MCAT Organic Chemistry - Problem Drill 23: Amino Acids, Peptides and Proteins MCAT rganic Chemistry - Problem Drill 23: Amino Acids, Peptides and Proteins Question No. 1 of 10 Question 1. Which amino acid does not contain a chiral center? Question #01 (A) Serine (B) Proline (C)

More information

A disaccharide is formed when a dehydration reaction joins two monosaccharides. This covalent bond is called a glycosidic linkage.

A disaccharide is formed when a dehydration reaction joins two monosaccharides. This covalent bond is called a glycosidic linkage. CH 5 Structure & Function of Large Molecules: Macromolecules Molecules of Life All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic

More information

AMINO ACIDS & PEPTIDE BONDS STRUCTURE, CLASSIFICATION & METABOLISM

AMINO ACIDS & PEPTIDE BONDS STRUCTURE, CLASSIFICATION & METABOLISM AMINO ACIDS & PEPTIDE BONDS STRUCTURE, CLASSIFICATION & METABOLISM OBJECTIVES At the end of this session the student should be able to, recognize the structures of the protein amino acid and state their

More information

Myoglobin and Hemoglobin

Myoglobin and Hemoglobin Myoglobin and Hemoglobin Myoglobin and hemoglobin are hemeproteins whose physiological importance is principally related to their ability to bind molecular oxygen. Myoglobin (Mb) The oxygen storage protein

More information

ATOMS AND BONDS. Bonds

ATOMS AND BONDS. Bonds ATOMS AND BONDS Atoms of elements are the simplest units of organization in the natural world. Atoms consist of protons (positive charge), neutrons (neutral charge) and electrons (negative charge). The

More information

Chapter 12 - Proteins

Chapter 12 - Proteins Roles of Biomolecules Carbohydrates Lipids Proteins 1) Catalytic 2) Transport 3) Regulatory 4) Structural 5) Contractile 6) Protective 7) Storage Nucleic Acids 12.1 -Amino Acids Chapter 12 - Proteins Amino

More information

Chapter 2 The Chemical Context of Life

Chapter 2 The Chemical Context of Life Chapter 2 The Chemical Context of Life Multiple-Choice Questions 1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living

More information

BIOLOGICAL MEMBRANES: FUNCTIONS, STRUCTURES & TRANSPORT

BIOLOGICAL MEMBRANES: FUNCTIONS, STRUCTURES & TRANSPORT BIOLOGICAL MEMBRANES: FUNCTIONS, STRUCTURES & TRANSPORT UNIVERSITY OF PNG SCHOOL OF MEDICINE AND HEALTH SCIENCES DISCIPLINE OF BIOCHEMISTRY AND MOLECULAR BIOLOGY BMLS II / B Pharm II / BDS II VJ Temple

More information

Non-Covalent Bonds (Weak Bond)

Non-Covalent Bonds (Weak Bond) Non-Covalent Bonds (Weak Bond) Weak bonds are those forces of attraction that, in biological situations, do not take a large amount of energy to break. For example, hydrogen bonds are broken by energies

More information

http://faculty.sau.edu.sa/h.alshehri

http://faculty.sau.edu.sa/h.alshehri http://faculty.sau.edu.sa/h.alshehri Definition: Proteins are macromolecules with a backbone formed by polymerization of amino acids. Proteins carry out a number of functions in living organisms: - They

More information

Chemical Basis of Life Module A Anchor 2

Chemical Basis of Life Module A Anchor 2 Chemical Basis of Life Module A Anchor 2 Key Concepts: - Water is a polar molecule. Therefore, it is able to form multiple hydrogen bonds, which account for many of its special properties. - Water s polarity

More information

Keystone Review Practice Test Module A Cells and Cell Processes. 1. Which characteristic is shared by all prokaryotes and eukaryotes?

Keystone Review Practice Test Module A Cells and Cell Processes. 1. Which characteristic is shared by all prokaryotes and eukaryotes? Keystone Review Practice Test Module A Cells and Cell Processes 1. Which characteristic is shared by all prokaryotes and eukaryotes? a. Ability to store hereditary information b. Use of organelles to control

More information

The peptide bond is rigid and planar

The peptide bond is rigid and planar Level Description Bonds Primary Sequence of amino acids in proteins Covalent (peptide bonds) Secondary Structural motifs in proteins: α- helix and β-sheet Hydrogen bonds (between NH and CO groups in backbone)

More information

Hair. *credit to Anthony and Patti Bertino for image. Dec 2 8:10 PM

Hair. *credit to Anthony and Patti Bertino for image. Dec 2 8:10 PM Hair *credit to Anthony and Patti Bertino for image Dec 2 8:10 PM 1 Essential Question: How can hair be used to solve a crime? Dec 2 8:12 PM 2 History of hair evidence criminal evidence in 1800's 1883

More information

Structure of proteins

Structure of proteins Structure of proteins Primary structure: is amino acids sequence or the covalent structure (50-2500) amino acids M.Wt. of amino acid=110 Dalton (56 110=5610 Dalton). Single chain or more than one polypeptide

More information

I N V E S T I C E D O R O Z V O J E V Z D Ě L Á V Á N Í

I N V E S T I C E D O R O Z V O J E V Z D Ě L Á V Á N Í I V E S T I E D Z V J E V Z D Ě L Á V Á Í AMIAIDS PEPTIDES AMIAIDS = substitutional/functional derivatives of carboxylic acids = basic units of proteins (2-aminoacids) General formula of 2-aminoacids (α-aminoacids):

More information

Guidelines for Writing a Scientific Paper

Guidelines for Writing a Scientific Paper Guidelines for Writing a Scientific Paper Writing an effective scientific paper is not easy. A good rule of thumb is to write as if your paper will be read by a person who knows about the field in general

More information

Chapter 3 Molecules of Cells

Chapter 3 Molecules of Cells Bio 100 Molecules of cells 1 Chapter 3 Molecules of Cells Compounds containing carbon are called organic compounds Molecules such as methane that are only composed of carbon and hydrogen are called hydrocarbons

More information

Proteins. Proteins. Amino Acids. Most diverse and most important molecule in. Functions: Functions (cont d)

Proteins. Proteins. Amino Acids. Most diverse and most important molecule in. Functions: Functions (cont d) Proteins Proteins Most diverse and most important molecule in living i organisms Functions: 1. Structural (keratin in hair, collagen in ligaments) 2. Storage (casein in mother s milk) 3. Transport (HAEMOGLOBIN!)

More information

Nafith Abu Tarboush DDS, MSc, PhD natarboush@ju.edu.jo www.facebook.com/natarboush

Nafith Abu Tarboush DDS, MSc, PhD natarboush@ju.edu.jo www.facebook.com/natarboush Nafith Abu Tarboush DDS, MSc, PhD natarboush@ju.edu.jo www.facebook.com/natarboush α-keratins, bundles of α- helices Contain polypeptide chains organized approximately parallel along a single axis: Consist

More information

Ch18_PT MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Ch18_PT MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Ch18_PT MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) All of the following can be classified as biomolecules except A) lipids. B) proteins. C)

More information

CHAPTER 29 AMINO ACIDS, POLYPEPTIDES, AND PROTEINS SOLUTIONS TO REVIEW QUESTIONS

CHAPTER 29 AMINO ACIDS, POLYPEPTIDES, AND PROTEINS SOLUTIONS TO REVIEW QUESTIONS APTER 29 AMI AIDS, PLYPEPTIDES, AD PRTEIS SLUTIS T REVIEW QUESTIS 1. The designation, α, means that the amine group in common amino acids is connected to the carbon immediately adjacent to the carboxylic

More information

1. The diagram below represents a biological process

1. The diagram below represents a biological process 1. The diagram below represents a biological process 5. The chart below indicates the elements contained in four different molecules and the number of atoms of each element in those molecules. Which set

More information

Molecular Models in Biology

Molecular Models in Biology Molecular Models in Biology Objectives: After this lab a student will be able to: 1) Understand the properties of atoms that give rise to bonds. 2) Understand how and why atoms form ions. 3) Model covalent,

More information

Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory.

Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory. Acid-base 2816 1 Acid-base theories ACIDS & BASES - IONIC EQUILIBRIA LEWIS acid electron pair acceptor H +, AlCl 3 base electron pair donor NH 3, H 2 O, C 2 H 5 OH, OH e.g. H 3 N: -> BF 3 > H 3 N + BF

More information

THE CHEMICAL SYNTHESIS OF PEPTIDES

THE CHEMICAL SYNTHESIS OF PEPTIDES TE EMIAL SYTESIS F PEPTIDES Peptides are the long molecular chains that make up proteins. Synthetic peptides are used either as drugs (as they are biologically active) or in the diagnosis of disease. Peptides

More information

REVISION NO : 3 August 2010

REVISION NO : 3 August 2010 1. PRODUCT AND COMPANY IDENTIFICATION Product Name Magnesium Powder Chemical Symbol Mg CAS No 7439-95-4 EINECS No 231-104-6 Supplier Name & Address THE METAL POWDER COMPANY LTD Thirumangalam - 625706 Tamil

More information

Type of Chemical Bonds

Type of Chemical Bonds Type of Chemical Bonds Covalent bond Polar Covalent bond Ionic bond Hydrogen bond Metallic bond Van der Waals bonds. Covalent Bonds Covalent bond: bond in which one or more pairs of electrons are shared

More information

AP BIOLOGY 2008 SCORING GUIDELINES

AP BIOLOGY 2008 SCORING GUIDELINES AP BIOLOGY 2008 SCORING GUIDELINES Question 1 1. The physical structure of a protein often reflects and affects its function. (a) Describe THREE types of chemical bonds/interactions found in proteins.

More information

Compartmentalization of the Cell. Objectives. Recommended Reading. Professor Alfred Cuschieri. Department of Anatomy University of Malta

Compartmentalization of the Cell. Objectives. Recommended Reading. Professor Alfred Cuschieri. Department of Anatomy University of Malta Compartmentalization of the Cell Professor Alfred Cuschieri Department of Anatomy University of Malta Objectives By the end of this session the student should be able to: 1. Identify the different organelles

More information

SAFETY DATA SHEET CLEENOL LIFT WAX FREE POLISH

SAFETY DATA SHEET CLEENOL LIFT WAX FREE POLISH Revision Date 18/06/2010 Revision 1 Supersedes date 18/06/2010 SAFETY DATA SHEET SECTION 1: IDENTIFICATION OF THE SUBSTANCE/MIXTURE AND OF THE COMPANY/UNDERTAKING 1.1. Product identifier Product name 1.2.

More information

Chemical Bonds and Groups - Part 1

Chemical Bonds and Groups - Part 1 hemical Bonds and Groups - Part 1 ARB SKELETS arbon has a unique role in the cell because of its ability to form strong covalent bonds with other carbon atoms. Thus carbon atoms can join to form chains.

More information

Notes on Hair Analysis

Notes on Hair Analysis Notes on Hair Analysis I have found local veterinarians very uncooperative when trying to get samples of dog and cat fur. I have found neighbors, friends and relatives a much better source of fur. There

More information

NO CALCULATORS OR CELL PHONES ALLOWED

NO CALCULATORS OR CELL PHONES ALLOWED Biol 205 Exam 1 TEST FORM A Spring 2008 NAME Fill out both sides of the Scantron Sheet. On Side 2 be sure to indicate that you have TEST FORM A The answers to Part I should be placed on the SCANTRON SHEET.

More information

BIOLOGICAL MOLECULES OF LIFE

BIOLOGICAL MOLECULES OF LIFE BIOLOGICAL MOLECULES OF LIFE C A R B O H Y D R A T E S, L I P I D S, P R O T E I N S, A N D N U C L E I C A C I D S The Academic Support Center @ Daytona State College (Science 115, Page 1 of 29) Carbon

More information

Activity 4/5.1 How Can You Identify Organic Macromolecules?

Activity 4/5.1 How Can You Identify Organic Macromolecules? Answers? Activity 4/5.1 ow an You Identify rganic Macromolecules? efer to the figure (Some Simple hemistry) on the next page when doing this activity. Part A. Answer the questions. Then use your answers

More information

Candidate Style Answer

Candidate Style Answer Candidate Style Answer Chemistry A Unit F321 Atoms, Bonds and Groups High banded response This Support Material booklet is designed to accompany the OCR GCE Chemistry A Specimen Paper F321 for teaching

More information

Applications of nanotechnology: Cosmetics

Applications of nanotechnology: Cosmetics Applications of nanotechnology: Cosmetics Course on Health Effects of Engineered Nanomaterials Finnish Institute of Occupational Health, 23 April 2013 Sari Karjomaa Finnish Cosmetic, Toiletry and Detergent

More information

Name: Hour: Elements & Macromolecules in Organisms

Name: Hour: Elements & Macromolecules in Organisms Name: Hour: Elements & Macromolecules in Organisms Most common elements in living things are carbon, hydrogen, nitrogen, and oxygen. These four elements constitute about 95% of your body weight. All compounds

More information

Amino Acids as Acids, Bases and Buffers:

Amino Acids as Acids, Bases and Buffers: Amino Acids as Acids, Bases and Buffers: - Amino acids are weak acids - All have at least 2 titratable protons (shown below as fully protonated species) and therefore have 2 pka s o α-carboxyl (-COOH)

More information

Level 3 Advanced Technical Diploma in Hairdressing (540) (6002-31)

Level 3 Advanced Technical Diploma in Hairdressing (540) (6002-31) Level 3 Advanced Technical Diploma in Hairdressing (540) (6002-31) Sample test Total marks: 60 Duration : 80 minutes (S1 Ref.2.1) Knowledge Q1a. Label the diagram of the skin. (3 marks) Q1a. Answer, 1

More information

CERRITOS COLLEGE TECHNOLOGY DIVISION COSMETOLOGY DEPARTMENT ACTION OF CHEMICALS

CERRITOS COLLEGE TECHNOLOGY DIVISION COSMETOLOGY DEPARTMENT ACTION OF CHEMICALS Revised 7-01 CR # 1 CERRITOS COLLEGE TECHNOLOGY DIVISION COSMETOLOGY DEPARTMENT ACTION OF CHEMICALS I. SODIUM HYDROXIDE Functions by swelling the fibers and softens the main disulfide bonds which link

More information

Hydrogen Bonds The electrostatic nature of hydrogen bonds

Hydrogen Bonds The electrostatic nature of hydrogen bonds Hydrogen Bonds Hydrogen bonds have played an incredibly important role in the history of structural biology. Both the structure of DNA and of protein a-helices and b-sheets were predicted based largely

More information

SAFETY DATA SHEET BOSTIK AQUAGRIP 536

SAFETY DATA SHEET BOSTIK AQUAGRIP 536 Revision Date November 2014 1 / 6 SAFETY DATA SHEET BOSTIK AQUAGRIP 536 According to Regulation (EC) No 1907/2006 SECTION 1: IDENTIFICATION OF THE SUBSTANCE/MIXTURE AND OF THE COMPANY/UNDERTAKING 1.1.

More information

X-Plain Alopecia Reference Summary

X-Plain Alopecia Reference Summary X-Plain Alopecia Reference Summary Introduction Hair loss is very common in both men and women. You or someone you love may be experiencing hair loss. Hair follicle Learning about normal hair growth is

More information

Biochemistry of Cells

Biochemistry of Cells Biochemistry of Cells 1 Carbon-based Molecules Although a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules Organic chemistry is the study of carbon compounds Carbon

More information

The Molecules of Cells

The Molecules of Cells The Molecules of Cells I. Introduction A. Most of the world s population cannot digest milk-based foods. 1. These people are lactose intolerant because they lack the enzyme lactase. 2. This illustrates

More information

Ms. Campbell Protein Synthesis Practice Questions Regents L.E.

Ms. Campbell Protein Synthesis Practice Questions Regents L.E. Name Student # Ms. Campbell Protein Synthesis Practice Questions Regents L.E. 1. A sequence of three nitrogenous bases in a messenger-rna molecule is known as a 1) codon 2) gene 3) polypeptide 4) nucleotide

More information