headstart biology AS
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- Created by: charlie
- Created on: 01-09-13 16:14
proteins
- made from: 20 diff amino acids (C, H2, O2, N2, some S)
- held by strong covalent bonds
- order of AA ---> determines structure of P ---> determines how it works
- each protein has original shape
primary structure
- order in which AA are arranged in a chain
secondary structure
- chains coil/ fold to pleats ---> held by weak forces of chem attraction (H2 bonds)
tertiary structure
- coil chain folded ---> ball ---> weak chem. bonds (H2) + strong (S bridges)
- protein roughly spherical = globular protein (e.g. enzymes)
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carbohydrates
- made from: C, H2, O2 ... e.g. sugars, starch, cellulose (small, water-soluble, sweet molecules)
- monosaccharides: single units from which all othe carbs built ---> glucose + fructose
- disaccharides: 2 MS joined by chem. reaction + molecule of water (so condensation reaction)
- e.g. GLU+GLU=MALTOSE + WATER or GLU+FRU=SUCROSE + WATER
starch is a polysaccharide
- polymers- large molecules made from monomers which are monosaccharide
- made from 2 PS= amylose + amylopectin (polmers of glucose)
- insoluble starch ---> good for storing glucose + ONLY found in plant cells
cellulose is a PS
- polymer of glucose (like starch but bonding is diff.)
- cellulose molecules long + straight ---> several lie side by side---> form microfibrils (strengthens plant cell wall)
- molecules held by weak H2 bonds
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lipids
oils + fats made from: C, H2, O2
triglycerides
- group of lipids that make up plant oils+animal fats
- made from glycerole molecule + 3 fatty acids
a fatty acid= long chain of carbons, acid group at end(-COOH), double bond to O2, H2 molecules
- saturated fatty acid= every carbon joined by single bond
- unsaturated= one double bond or polyunsaturated= more than one double bond
phospholipids= special type of lipid
- glycerole molecule, 2 fatty acids, phosphate group
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enzymes
- speed up biochemical reactions acting as biological catalysts inc. ROR
- sum of reactions = metabolism single chain reaction= metabolic pathway
activation energy
- every reaction requires e input= activation energy
- reaction needing high activation energy cant start at low temps
- enzymes reduce acitvation energy
enzymes are proteins
- globular proteins + order of amino acids determine structure + how it works
- break down or build molecules
- e.g digestive enzymes- help break down food to smaller molecules
- e.g DNA polymerase- builds molecules in DNA replication
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enzymes part 2
active site
- substrate= substance thats acted upon enzyme
- active site= region of surface- substrate attaches + where catalyed reaction takes place
- soon as enzyme-substrate complex formed ---> products of rection released + start again
enzymes are specific
- catalyses one specific chemical reaction + substrate must be correct shapeto active site
- only one substrate will fit so only one chem. reaction
- change in active site affects enzyme performance
temperature
- inc. reaction faster as more e for enzyme
- high temp. vibrate rapidly + break weak bonds holding tertiary structure- shape changes + substrate no longer fits = denatured
pH ---> acids+alkalis can denature enzymes ---> hydrogen ions (H+) in acids + hydroxyl ions (OH-)in alakalis disrupt weak bonds + change active site
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