Carbohydrates. The Molecules of Life

Transcription

1 Carbohydrates The Molecules of Life The 4 types of Biological Molecules are: Carbohydrates Lipids Proteins Nucleic Acids organic compounds made of C, H and O About 2x as much H as O (CH2O) Saccharide = carbohydrate Monomers = monosaccharides Dimers = disaccharides Polymers = polysaccharides Monosaccharides Also called simple sugars Examples: glucose, fructose and galactose All 3 are isomers Used as energy (food) by organisms Fructose Monosaccharides Monosaccharides can be classified by the number of carbon atoms they contain: diose (2), triose (3), tetrose (4), pentose (5), hexose (6), heptose (7), and so on glucose, galactose & fructose are hexoses some pentoses include xylose ("wood sugar") and ribose (in RNA) and deoxyribose (in DNA) xylose Sugar, Sugar Disaccharides Made of 2 monosaccharides linked together by a dehydration synthesis/condensation reaction Also used as food/energy ex. sucrose (table sugar) = glucose + fructose lactose (in milk) = glucose + galactose maltose (malt sugar) = glucose + glucose Nutrasweet Splenda

2 Polysaccharides Oligosaccharides contain a small number of monosaccharides (3 to 9ish) many functions including cell recognition markers on the surface of cell membranes often found in combination with proteins or lipids 3 or more monosaccharides linked together Examples: glycoprotein = carb + protein glycolipid = carb + lipid Glycogen energy storage in animals Starch energy storage in plants Cellulose makes up plant cell walls and wood Chitin - makes up arthropod exoskeletons & fungi cell walls Starch, Glycogen and Cellulose Monomer is glucose Starch in a potato Glycogen in human cells cicada exoskeletons are made of chitin Glycosidic Bonds glycosidic bond: A covalent bond that joins a carbohydrate molecule to another group joins monosaccharides together in di-, oligo-, and polysaccharides Cellulose in leaves Lipids Carbohydrates Summary Function as food energy (mono- and di- saccharides) or stored energy (starch/glycogen), and structural support (cellulose/chitin) Monomers are called Monosaccharides ex. glucose, fructose, galactose Dimers are called disaccharides ex. lactose, sucrose, maltose Polymers are called polysaccharides ex. glycogen, starch, cellulose, chitin Large nonpolar/hydrophobic organic molecules made mainly of C, H and O Made of: Fatty acids unbranched carbon chains Carboxyl group at one end is hydrophilic Rest of hydrocarbon is hydrophobic Condensation Reaction Fatty Acid

3 Triglycerides Fatty Acids Saturated = no double bonds, C atoms are 'saturated' with H Unsaturated = double bonds, C atoms not 'saturated' with H 3 fatty acids attached to one glycerol Function = energy/energy storage Saturated triglycerides = fats Unsaturated triglycerides = oils saturated fatty acids, solid at room temp. unsaturated fatty acids, liquid at room temp. Glycerol double bond = unsaturated animals have mainly saturated fats ex. foods - bacon, other meats plants have mainly unsaturated fats ex. foods - nuts, seeds unsaturated fatty acids can be monounsaturated = one bouble bond polyunsaturated = multiple double bonds cis and trans fats unsaturated fats in nature are cis and are bent trans fatty acids are produced synthetically to be straight like a saturated fatty acid Cis = Both sides of double bond point the same way Trans = Sides point different ways

4 Waxes Steroids Function = structure/protection 4 fused carbon rings ex. earwax, waxy coatings in plants, beeswax Functions = hormones, vitamins, other functions Waterproof (hydrophobic) ex. cholesterol, testosterone Long chains of fatty acids Anabolic steroids: usually variants of testosterone Can cause serious health problems Phospholipids 2 fatty acids attached to a glycerol/phosphate Make up cell membranes called the phospholipid bilayer Hydrophilic 'heads', hydrophobic 'tails' Lipids Summary Function as energy storage (triglycerides), hormones (steroids), structural support (waxes/phospholipids/cholesterol) all polymers/no real monomers except the carbon rings in steroids & fatty acids in waxes phospholipids made of 2 fatty acids/glycerol/phosphate triglycerides made of 3 fatty acids/glycerol unsaturated - double bonds/oils saturated - no double bonds/fats steroids made of fused carbon rings waxes made of chains of fatty acids Proteins Mainly made of C, H, O, N, & sometimes S Examples of proteins: catalase enzyme which breaks down H2O2 Functions: enzymes (catalysts), hormones, structure, movement, transport, antibodies, energy Monomers = amino acids Dimers = dipeptides Polymers = polypeptides insulin hormone which regulates blood sugar

5 hemoglobin carries oxygen in the blood; contains Fe (iron) to bond to O2 actin multifunctional protein including - movement, muscle contraction & structural support iron muscle fibers featuring actin and other proteins hemoglobin molecule Amino Acids immunoglobulin (aka antibody) - recognize & bind to antigens in immune responses each type of antibody binds to a specific molecule called an antigen Central carbon bonded to: 1 hydrogen 1 carboxyl group -COOH 1 amino group -NH2 1 R group R group may vary and determines what amino acid it is R groups of the amino acids in proteins determine protein shape and function Peptide Bonds Peptide Bond = Covalent bond between amino acids Protein Structure There are 4 levels of protein structure Form by condensation reaction / dehydration synthesis 2 amino acids = dipeptide Long chain of amino acids = polypeptide Peptide Bond Formation Level 2 = Secondary An α Helix or β Sheets Level 1 = Primary A polypeptide made of amino acids -Shape is determined by hydrogen bonding b/w amino acids

6 Protein Structure Level 3 = Tertiary multiple lvl.2 (helices and sheets) Proteins Summary Function as catalysts (enzymes), hormones (insulin), movement (actin/myosin/muscles), structural support (actin & others), energy (most proteins can be broken down for energy), antibodies, and other misc functions (ex. hemoglobin bonds to O2) monomers are called amino acids many types based on R groups -proteins are fully formed at level 4 dimers are called dipeptides -Protein shape determines function Level 4 = Quaternary Multiple tertiary structures polymers are called polypeptides Nucleotides Nucleic Acids function to store information the code for life Monomers = nucleotides dimers = dinucleotides Polymers = polynucleotides (DNA, RNA) Each nucleotide is made of a sugar, a phosphate and a nitrogenous base phosphate sugar Dinucleotides 2 nucleotides joined together at phosphates ex. NAD (nicotinamide adenine dinucleotide) - a coenzyme - works together with an enzyme to catalyze a reaction, carries e-/energy in rxns Sugar-Phosphate Backbone The sugar/phosphate parts of nucleotides are what join together to form the 'backbone' of DNA/RNA SugarPhosphate backbone Nucleotide There are 5 kinds of nitrogenous bases: Adenine (A) Thymine (T) (DNA only) Cytosine (C) Guanine (G) Uracil (U) (RNA only)

7 DNA Nucleotides are joined together by a phosphodiester bond between the phosphate groups and sugars in the sugar-phosphate backbone DNA = deoxyribonucleic acid Sugar in nucleotides = deoxyribose 2 polynucleotides in a 'twisted ladder' called a double helix The sequence of nitrogenous bases (A,T,C & G) determines the genetic information RNA ATP ATP = adenosine triphosphate (3 phosphates) function: Energy currency in living cells RNA = ribonucleic acid Sugar in nucleotides = ribose Uracil (U) instead of Thymine (T) single chain/strand transcribed from DNA contain genetic info multiple types and functions Nucleic Acids Summary Function mainly as information storage (DNA/RNA) but also as energy currency (ATP) monomers are called nucleotides different types based on the 5 different nitrogenous bases (A,C,T,G,U) and the 2 sugars deoxyribose in DNA and ribose in RNA Releases lots of free energy for cells to do work ATP is a modified nucleotide with 3 phosphates containing extra energy dimers are called dinucleotides (ex. NAD) polymers are called polynucleotides ex. DNA (double stranded) and RNA (single stranded)