WJEC-A Level Biology-Unit 1.11 Basic Biochemistry and Cell Organisation

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normally cause a cell to burst 2 - 1-4 glycosidic bonds Hydrogen bonds link adjacent chains Chitin: Found in fungal cell walls and exoskeletons of insects. OH group is replaced with a nitrogen containing an acetylglucosamine group. PROTEINS: Proteins function as enzymes, hormones and oxygen transporters. Amino Acid Structure: H basic group. Overall, this is a NEUTRAL MOLECULE H Alanine: -Possesses one. H NH₂ R Amino Side Group Chain Individual amino acids display a tetrahedral shape due to the angles of the bonds between the atoms - The simplest of the amino acids possesses a hydrogen atom for its R group. This amino acid is called GLYCINE. H Formation of a Dipeptide: R₁ amino acid(1) NH₂ H -O-H R₁ N-C-C T CH3 H | tf H H amino acid(2) NH -H₂O dipeptide Carboxyl Group R₂ H H COOH H =O -COOH OH 3 Primary Structure - The sequence of amino acids. Secondary Structure Two main types -----> a Helix B-pleated sheet Tertiary Structure Quaternary Structure -Result of H-bonding between the -CO and -NH of adjacent amino acids. Three dimensional shape of the protein. Functions of proteins: ● Enzymes (Amylase) ● the arrangement of multiple protein subunits in a single protein complex. Transport (Haemoglobin) Movement (Actin and Myosin) Cell Recognition (Antigens) Channels (Membrane proteins) Structure (Collagen and Keratin) Hormones (Insulin) ● Protection (Antibodies) Fibrous vs Globular proteins: Fibrous: Little or no tertiary structure Long parallel polypeptide chains Cross linkages at intervals Long fibres and sheets formed Mostly insoluble - Most have a structural role - Keratin in hair and outer layer of skin - Collagen in connective tissues Bones, teeth, tendons & vessel walls Globular: A complex tertiary structure Soluble Some have quaternary structure Roles in metabolic reactions - Folded into spherical/globular shape 4 Lipids- Fats and Oils: General formula of saturated fatty acid- CnH₂nO2 General formula of unsaturated fatty acid- C,H(2n-2) 0₂ Monounsaturated fatty acid - one C=C bond Polyunsaturated fatty acid - more than one C=C bond - Saturated fatty acids often used to make animal lipids. Solid at room temp ---->Fats used to make plant lipids Liquid at room temp ---->Oils Unsaturated fatty acids Structure of a triglyceride: Carboxyl group-COOH Found at end of hydrocarbon chain of a fatty acid (lipid) And in an amino acid Esterification: - Condensation reaction Happens 3 times to form a triglyceride H H-C-OH H-C-OH H-C-OH H GLYCEROL Triglyceride uses in animals: Glycerol H H HO-C-R 유 HO-C-R H-C-o-C–CH2–CH,…CH2–CH2–CH3 H-C-o-C-CH,CH2CH2–CH2–CH3 H=C-o-C–CH2–CH,…CH,—CH,—CH, 유 HO-C-R O FAITY ACIDS O Triglyceride O CONDENSATION 3 fatty acid chains HYDROLYSIS ESTER BOND 0 : H-C-0-C-R H H-C-0-C-R 유 H-C-0-C-R Phospholipids: One fatty acid can be replaced by a polar phosphate group Cholesterol molecules are located between the tails of the phospholipid molecules where they serve to stabilise the membrane--->classified as LIPIDS but are in the subgroup of steroids H TRIGLYCERIDE They contain MORE energy per gram than carbohydrate so are useful as a long term energy store. Fats can be stored in adipose cells and act as an insulating layer They have low density so they can provide buoyancy. Head + 3H₂O Tail Phospholipid Phosphate group Glycerol 5