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BIOCHEMISTRY

BIOCHEMISTRY. © 2007 Paul Billiet ODWS. CARBON. Tetravalent  4 different bonds  variety  isomerism Forms long chains (polymers)  macromolecules and ring structures Tetrahedral structure  3-D variation  optical isomerism. © 2007 Paul Billiet ODWS. Organic compounds.

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BIOCHEMISTRY

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  1. BIOCHEMISTRY © 2007 Paul Billiet ODWS

  2. CARBON • Tetravalent  4 different bonds  variety  isomerism • Forms long chains (polymers)  macromolecules and ring structures • Tetrahedral structure  3-D variation  optical isomerism © 2007 Paul Billiet ODWS

  3. Organic compounds • Compounds containing carbon found in living organisms • Not including carbonates, hydrogen carbonates, CO2 or CO • Often based upon a skeleton of carbon • An infinite variety possible • Evolution has chosen a few for use in living organisms • There are four principal groups: sugars, fatty acids, amino acids and nucleotides © 2007 Paul Billiet ODWS

  4. Organization:Monosaccharides, Disaccharides, Polysaccharides Monosaccharides 5C pentoses (eg ribose, deoxyribose) 6C hexoses (eg glucose, fructose, galactose) OH C H H H RIBOSE C C GLUCOSE OH OH CH2OH C H O H C OH CH2OH OH O C C H H H H C C OH OH CARBOHYDRATES (CH2O)n © 2007 Paul Billiet ODWS

  5. OH OH C C O O H H H H H H C C C C OH OH OH OH CH2OH CH2OH C C H H H H C C OH OH Glycoside linkage to form disaccharides The two sugars are joined by condensation and may be broken by hydrolysis © 2007 Paul Billiet ODWS

  6. OH OH H O H O C C C C O H H H H H C C C OH OH OH CH2OH CH2OH C C H H H C OH A disaccharide + H2O © 2007 Paul Billiet ODWS

  7. Different monosaccharides can be used • sucrose = glucose + fructose • lactose = glucose + galactose • maltose = glucose + glucose © 2007 Paul Billiet ODWS

  8. Macromolecules Common ones based upon glucose Branched polysaccharides Amylose & amylopectin (starches) are synthesised in plants. Glycogen is synthesised in animals, more highly branched than starches = more compact Polysaccharides Unbranched polysaccharides • Cellulose in plant cell walls © 2007 Paul Billiet ODWS

  9. CARBOHYDRATEFUNCTIONS Sugars (mono and disaccharides) small molecules soluble in water: • Maintenance of osmotic balance (e.g. salts in blood plasma, plant cell turgidity); • transport of energy reserves (e.g. glucose in blood or sucrose in sap); • energy substrate (respiration and photosynthesis); • energy store (sugar cane); • flavouring (fruits); reward (nectar); • precursors (building blocks) of polysaccharides, nucleotides and amino acids © 2007 Paul Billiet ODWS

  10. CARBOHYDRATE FUNCTIONS • Polysaccharides Large molecules insoluble in water: • Osmotically inactive carbohydrate storage, (seeds, roots, chloroplasts); • Structural (cellulose in plants) © 2007 Paul Billiet ODWS

  11. LIPIDS C, H, O • More hydrogen (more reduced) than carbohydrates. • Insoluble in water, soluble in organic solvents (alcohols, acetone, chloroform etc) © 2007 Paul Billiet ODWS

  12. Carboxylic acid O C CH3 OH Hydrocarbon chain O C CH3 OH Fatty acids: carboxylic acid + long hydrocarbon chain A saturated fatty acid An unsaturated fatty acid © 2007 Paul Billiet ODWS

  13. © 2007 Paul Billiet ODWS

  14. HO - CH2 O HO - CH C CH3 OH HO – CH2 O C CH3 OH Fats and Oils fatty acids + glycerol (1, 2 or 3 = mono , di or triglycerides) Condensation reactions © 2007 Paul Billiet ODWS

  15. O - CH3 O - CH O C CH3 HO - CH3 O C CH3 Two fatty acids joining glycerol = A diglyceride +2H20 © 2007 Paul Billiet ODWS

  16. Phospholipids • in lipoprotein membranes (plasma, nuclear, mitochondrial etc.) © 2007 Paul Billiet ODWS

  17. Other lipids Steroids: multiple ring structures (e.g. cholesterol) • Functions: cell membrane structure, digestion (help to emulsify fats), hormones (testosterone etc), vitamins (e.g. Vitamin D), poisons Waxes: long chain alcohol + fatty acids • Water proof coating to leaves, fur feathers, insect exoskeletons. • Used by bees to construct their honey combs. © 2007 Paul Billiet ODWS

  18. LIPID FUNCTIONS IN GENERAL • STRUCTURAL: biological membranes (phospholipids, steroids, glycolipids), cushioning (fat deposits round the kidneys) • ELECTRICAL INSULATION: myelin sheath round axons • THERMAL INSULATION: subcutaneous fat deposits. • WATER PROOFING: waxes and oils • ENERGY STORE AND SUBSTRATE: very condensed form of energy (37 kJ g-1) used by animals and seeds. • HORMONES: steroids • VITAMINS: precursor to Vit D • BUOYANCY: oil droplets in plankton © 2007 Paul Billiet ODWS

  19. AMINO ACIDS&PROTEINS: C, H, O, N, S cysteine arginine methionine phenylalaline aspartic acid © 2007 Paul Billiet ODWS

  20. R H2N-C-COOH H Amino acids • amino group, carboxyl group, hydrogen and a variable side group (residue) each joined to a central carbon atom © 2007 Paul Billiet ODWS

  21. Types of amino acids • Amino end and carboxyl end can be ionised NH3+ and COO- to give acidic and basic characteristics • At pH 7 both groups are ionised. • The residues are side chains which give the individual properties to the amino acid (acidic, basic, neutral and nonpolar) © 2007 Paul Billiet ODWS

  22. Functions of amino acids • Protein synthesis, energy reserve, hormones (thyroxin) • 20 different amino acids used in protein synthesis though others do occur in nature. • Essential amino acids cannot be synthesised by the organism and must form part of their diet © 2007 Paul Billiet ODWS

  23. The peptide bond • Carboxyl group + amino group form a strong covalent bond releasing water in to process water = a condensation reaction (the reverse is hydrolysis) • Amino acids join together in a long chain: N terminal end to C terminal end = a polypeptide © 2007 Paul Billiet ODWS

  24. R R O O H H N C C-OH N C C-OH R O H H H + H2O N C C-OH H H H R O H N C C H H Condensation reaction A dipeptide is formed The peptide bond © 2007 Paul Billiet ODWS

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