The Molecules of Life - Overview. The Molecules of Life. The Molecules of Life. The Molecules of Life

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1 The Molecules of Life - Overview The Molecules of Life The Importance of Carbon Organic Polymers / Monomers Functions of Organic Molecules Origin of Organic Molecules The Molecules of Life Water is the universal medium for life But life is made up mostly of compounds based on the element carbon organic molecules Carbon enters the biosphere via autotrophic organisms convert CO 2 in the atmosphere into molecules of life The Molecules of Life Carbon forms large, complex and diverse molecules Protein, DNA, carbohydrates, etc. are all carbon-based based 1

2 Carbon backbone of life! Carbon cycle Organic chemistry study of carbon compounds Basis of organic molecules Reminder molecules are 3D! The Importance of Carbon Chemistry Review in Chapter 3 Forms covalent bonds: tetravalence The Importance of Carbon Form ~ Function 2

3 The Importance of Carbon Carbon forms a variety of covalent bonds single, double, & triple It also combines with a number of other elements such as H, O, N, S, and P The Importance of Carbon Versatility: infinite number of molecules Carbon carbon bonds: can produce long chains e.g. hydrocarbons Organic Polymers Small organic molecules (monomers) join together to form very large chains called macromolecules or polymers (small repeating subunits (monomers) form larger polymers)

4 Organic Polymers Four types of organic macromolecules are extremely important to life: Carbohydrates Proteins Lipids Nucleic acids Again each of these polymers is made up of smaller, repeating subunits Organic Macromolecules & Their Subunits (Monomers) Carbohydrates Proteins Lipids (Fats) Nucleic Acids Simple Sugars Amino Acids Glycerol & Fatty Acids Nucleotides Form of Carbohydrates Monosaccharides = sugar (glucose) What is a sugar? Form length carbonyl group hydroxyl group rings 4

5 Functions of Carbohydrates Carbohydrates Fuel molecules (e.g. C6H12O6 - glucose for cellular respiration) Medium to Long term energy storage (starch, glycogen) Structural molecules (e.g. cellulose in cell walls) Lipids Fats: glycerol and fatty acids Hydrophobic Lipids No polymers. Composed of groups of macromolecules macromolecules but they do not repeat themselves as seen in the other groups. Fats, Phospholipids, Steroids 5

6 Fat = glycerol + 3 glycerol + 3 FAs Lipids: Form Phospholipids = glycerol + 2 FAs + phosphate group Steroids = Carbon skeleton consisting of four fused rings Functions of Lipids Lipids Long term storage of energy (e.g. fats) Structural molecules (e.g. phospholipids in cell membranes) Hormones Proteins >50% of dry mass of most cells Functions Speed up reactions Structural functions Storage Transport Cellular communications Defense (Table 5.1 in Campbell) 6

7 Proteins Monomers Amino Acids Proteins Polymers Polypeptides 1+polypeptides Proteins Functions of Proteins Catalysts (enzymes) Structural molecules (e.g.( membranes, collagen, keratin) Proteins - Enzymes Catalytic Hydrolysis of sucrose to glucose & fructose 7

8 Two major groups Nucleic Acids DNA - provides directions for its own replication and directs RNA RNA - carries the genetic information to the Ribosome where it can be make into a protein Monomers Nucleotides Polymers Polynucleotides (Nucleic Acid) Functions of Nucleic Acids Nucleic Acids Store and transmit hereditary information DNA controls production of proteins Functions of Organic Molecules - Review They function chemically e.g.. fuel, fuel storage, catalyze reactions They have a structural function e.g.. cellulose in cell walls, phospholipids in cell membranes, collagen (protein), protein structure in membranes Nucleic acids store and transmit hereditary information DNA controls production of enzymes, hence controls many chemical reactions occurring in the organism 8

9 The Molecules of Life Where it all Began Oparin and Haldanes s Hypothesis - Organic molecules were synthesized from inorganic molecules in the conditions of the primitive earth (reducing environment) These conditions do not exit today Testing Hypotheses Before we get into Oparin & Haldane s hypothesis, lets talk about what an hypothesis actually is A tentative (Not yet fully supported) explanation for some observed phenomenon It is a possible answer to a question that arises from observing We test it through experimentation or through analysis of available information/data The Molecules of Life Where it all Began Oparin (Russian) & Haldane (British) independently came up with an hypothesis to how life began on earth (1920s) They suggested that earth s s early atmosphere was such that organic compounds could have formed from simple molecules Lightening and UV radiation in atmosphere Oceans were a primitive soup of organic molecules 9

10 Miller-Urey Ureys s Experiment (1953) Tested Oparin and Haldane s hypothesis (Figure 26.2 in Campbell) Recreated conditions of early earth s s atmosphere as scientist thought to exist then (water, hydrogen, methane, ammonia) Source of energy: electrical spark Modern Experiments Scientists now believe that hydrogen, ammonia & methane were not overly abundant in early atmosphere Experiments have been performed using a variety of gasses and energy sources Produced all 20 amino acids, some simple sugars, lipids, and components of DNA Strong supporting evidence for the emergence of life Other Hypotheses More evidence emerging which points to small pockets of the atmosphere which contained the molecules required Volcanoes & underwater volcanoes or vents are likely places of synthesis high in sulfur and iron compounds 10