Molecules of Life

1. Molecules of Life

2. Molecules of Life • Carbohydrates • monosaccharides • energy supply • Proteins • amino acids • structural components • Lipids • fatty acids • structural components, energy, hormones • Nucleic acids • nucleotides • DNA-genetic material

3. Composition of Molecules of Life • most are carbon based • organic compounds • unique to living systems • with exception of CO2 & carbides • carbon is necessary for life • electroneutral • never loses or gains electrons • always shares or forms covalent bonds

4. H|H--C--H|H Covalent Bonding • carbon can form 4 covalent bonds with other elements or with itself • has 4 electrons in outermost shell • makes each carbon atom a connecting point from which another molecule can branch in four directions

5. Covalent Bonding • since carbon can bind to itself • has capacity to construct endless numbers of carbon skeletons varying in size & branching patterns

6. Organic Compounds • chain of carbons in organic molecule is-carbon skeleton • branched or unbranched • double or single bonds • straight or arranged in ring form • each has unique 3-D shape • properties depend on carbon skeleton & on atoms attached to skeleton • groups of atoms participating in chemical reactions are functional groups H|C|||C|H

7. Functional Groups • OH- (hydroxyl) • C=O (carbonyl) • COOH (carboxyl) • NH2(amino) • SH-sulfhydryl group • PO3 (phosphate) Phosphate group

8. Classes of Molecules & Functional Groups • COOH & NH2- amino acids • hydroxyl groups-alcohols • carboxyl groups-carboxylic acids-acetic acid • sugars contain both-carbonyl group & several hydroxyl groups • phosphate groups-found on nucleic acids

9. Macromolecules • 4 main classes • macromolecules or polymers • consist of many identical or similar molecular units strung together • monomers • cells link monomers in anabolic reactions by dehydration synthesis • chemical reaction which removes water • broken down into constituent monomers by adding water • catabolic reactions-hydrolysis

10. Carbohydrates • composed of C, H & O • 1:2:1 ratio • Formula: (CH2O)n should give formula for any carbohydrate • may contain nitrogen, phosphate and/or sulfur • Monomers-monosaccharides • simple sugars • building blocks for all other carbohydrates • 2-10 monosaccharides form oligosaccharide • hundreds- polysaccharide. • hydrophilic • water loving • larger molecules are less soluble in water Glucose

11. Monosaccharides Glucose • simple sugars • single chain or ring of 3-7 carbons • named for number of carbons they contain • 5 carbons-pentoses • 6 carbons-hexoses • glucose contains 6 carbons-hexose • formula-C6H1206 • most important metabolic fuel in body • broken downATP + CO2 • fructose-6 carbon monosaccharide • same formula as glucose • fructose & glucose are isomers • chemical compounds with same molecular formula but with elements arranged in different configurations • Galactose-isomer of glucose & fructose Galactose Fructose

12. Disaccharides • double sugars • covalent bond- between hydroxyl groups of two simple sugars • physiologically important disaccharides Sucrose • sugar cane & sugar beets • Glucose + fructosesucrose + H2O • Lactose-found in milk of mammals • disaccharide of galactose & glucose • Maltose • major degradation product of starch • composed of 2 glucose monomers • Disaccharides-too large to pass through cell membranes • must be broken down into constituent parts by hydrolysis • Sucrose + H20 glucose + fructose.

13. Polysaccharides • complex carbohydrates • dehydration synthesis reactions add more monosaccharides polysaccharides • most carbohydrates in nature are in this form • fairly insoluble • make perfect storage molecules • Glycogen • major stored carbohydrate in animal liver & muscle cells • highly branched at aboutevery 8-10 residues • Starch • major form of stored carbohydrate in plants • Structure-identical to glycogen-less branching at every 20-30 residues • Cellulose • foundin plants • most abundant compound on earth • cannot be digested by humans

14. Lipids • contain mostly C & H • 1:2 ratio • also contain oxygen but less than carbohydrates • often have N, S & phosphorous • hydrophobic • do not dissolve in water • include neutral fats, phospholipids & steroids

15. Lipid Functions • physiologically important lipids have 4 major functions • structural components of biological membranes • cholesterol, phospholipids and glycolipids help form and maintain intracellular structures • energy reserves • provide 2X as much energy as carbohydrates • hormones & vitamins are a type of lipid-steroids • lipophilic bile acids • important for lipid solubilization

16. Lipids • composed of fatty acids & glycerol (an alcohol) • fatty acids-long-chain hydrocarbon molecules • hydrocarbon chains make lipids nonpolar and therefore insoluble in water • fat synthesis involves attaching 3 fatty acidchainsto one glycerol by dehydration synthesis-producing triglycerides • glycerol is always the same; fatty acid composition varies • length of neutral fat’s fatty acid chains & degree of saturation determine how solid a fat is at room temperature • saturated • fatty acids with no carbon to carbon double bonds • unsaturated • have double bonds • monounsaturated fats have one unsaturated bond • polyunsaturated fats have multiple unsaturated bonds • double bonds make for lower melting points • presence of unsaturated fatty acids makes fat liquid at room temperature

17. Hydrolysis of Triglycerides • Hydrolysis breaks triglycerides • fatty acid + glycerol

18. Steroids • large lipid molecules with carbon skeleton bent into 4 rings • most important one-cholesterol • obtained by absorption from animal products in diet • meat, cream & egg yolks • can also be made by the body • absolutely essential for life • component of cell membranes • raw material for Vitamin D, steroid hormones and bile salt synthesis • without cholesterol there would be no steroid hormones such as estrogen and testosterone and therefore no reproduction • without corticosteroids we would die

19. Proteins • C, H, O, N & small amounts of S & sometimes phosphorous • monomer-amino acids • 1-7 amino acids formpeptide • up to 100 form polypeptide • more than 100 comprise a protein

20. Proteins • most abundant organic compounds in human body • provide support for cells, tissues & organs and create a 3-D framework for body • contractile proteins allow for movement via muscle contractions • transport proteins carry insoluble lipids, respiratory gases & minerals in blood • serve as buffers; help to prevent dangerous pH changes • enzymes are proteins important in metabolic regulation • needed to speed rate of chemical reactions • protein hormones coordinate, control & influence metabolic activities of nearly every cell • important for defense • skin, hair, & nails protect underlying tissues from environment • antibodies protect us from disease • clotting proteins protect from us from bleeding out

21. Amino Acids • 20 amino acids • (excluding proline) contain carboxylic acid-COOH & amino-NH2 or aminegroup • functional groups are attached to same carbon atom • R group attaches to same carbon • amino acid is distinguished by its particular R-group • 2 broad classes based upon whether R-group is hydrophobic or hydrophilic • hydrophobic repel aqueous environments • reside predominantly in interiorof proteins • hydrophilic amino acids interact with aqueous environments & often form H-bonds • found predominantly on exterior of proteins

22. Protein Structure • each protein contains unique sequence of amino acids • four levels of protein structure • Primary • Secondary • Tertiary • Quaternary

23. Structure & Function • structure determines function • shape of protein allows it to carry out specific duties • proteins whose job is to fill in a space (active site) on another molecule are globular in shape • those that make up something like muscles or tendons are fibrous • shapes depend on environmentalcharacteristics • ionic composition, pH & temperature • non homeostatic change in any of these will denature protein • denaturation causes protein to lose shape • loss of shapecannot function properly

24. Nucleic Acids • largest, organic molecules in body • C, H, O, N, & phosphorous • consists of long stretches of nucleotides • monomer for nucleic acids • provide directions for building proteins • 2 main types • RNA • translates DNA code • DNA • contains genetic information that is inherited from our parents

25. Nucleic Acids • RNA • single polynucleotide chain • DNA • double helix form • two polynucleotide chains wrapped around one another

26. Nucleic Acids • exist in mono-, di-, & tri-phosphorylated forms • often abbreviated to AMP • Mono, Di- & tri-phosphorylated forms of adenosine are abbreviated AMP, ADP & ATP • phosphate bonds are high energy bonds • meaning they contain energy • When broken they yield 7kcals • ATP ADP + Pi + energy • ATP is energy currency of all cells