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Infection and response
Organisation
Cell biology
Biological molecules
Homeostasis and response
Responding to change (a2 only)
Energy transfers (a2 only)
The control of gene expression (a-level only)
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
Britain & the wider world: 1745 -1901
Inter-war germany
World war one
2n revolution and dictatorship: russia, 1917-1953
World war two & the holocaust
1l the quest for political stability: germany, 1871-1991
The cold war
2j america: a nation divided, c1845-1877
Medieval period: 1066 -1509
The fight for female suffrage
2m wars and welfare: britain in transition, 1906-1957
2d religious conflict and the church in england, c1529-c1570
Britain: 1509 -1745
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03/04/2023
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WJEC-A Level Biology-Unit 1.11 Basic Biochemistry and Cell Organisation Organic Molecules: The importance of carbon: ● Can form 4 bonds Forms strong covalent bonds Can form long chains Can form rings- this means that carbon compounds can form huge macromolecules ● ● Monomers join to form: polysaccharides, proteins, lipids and nucleic acids. CARBOHYDRATES: → Carbohydrates are made from carbon, hydrogen and oxygen. They are organic molecules. → They store energy in plants and animals. →Plant cell walls depend on the structural role of some carbohydrates. → Made up of Monosaccharides, Disaccharides and Polysaccharides. HO Monosaccharides: General formula: (CH₂O), CH₂OH OH HO Alpha-(a) Glucose CH₂OH OH HO HO Fructose OH CH₂OH HO CH₂OH HO 6 OH HO Beta-(B) Glucose CH₂OH -O OH OH 0 Galactose OH OH The alpha glucose and beta glucose are structural isomers. 1 Disaccharides: > General Formula: C₁2H22O11 ► Disaccharides are sugars composed of two monosaccharides covalently bonded together by a glycosidic linkage. Maltose Glucose + Glucose ➤ Lactose Glucose + Galactose > Sucrose= Glucose + Fructose Polysaccharides: ★ Polymerisation: process of bonding many MONOMERS by condensation reactions to form one large molecule. Polysaccharides Starch Cellulose Glycogen Starch: Amylose a-Glucose Monomer a-Glucose B-Glucose a-Glucose 1-4 glycosidic bonds Spiral structure Amylopectin a-Glucose - 1-4 and some 1-6 glycosidic bonds Branched structure Glycosidic Bond Glycogen: Insoluble compact store of glucose in animals. - a-Glucose - 1-4 and 1-6 glycosidic bonds - Branched Structure Cellulose: Structural polysaccharide in plants. B-Glucose 1,4 and 1,6 1,4 1,4 and 1,6 Causes every other glucose to be upside down allowing the chains to hydrogen bond together making microfibrils All these microfibrils make fibres with extremely high tensile strength This means cellulose can be stretched without breaking Which allows plant cells to withstand high osmotic pressures that would...
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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