biology Unit 1 Mr Calver pg 4-15

  • Created by: charlie
  • Created on: 13-10-13 21:39


  • Infectious (communicable disease)- can catch- pathogens: bacteria, viruses, fungi, parasites e.g influenza, cholera
  • Lifestyle (non communicable disease)- cant catch- environ. factors: smoking, diet, pollution... e.g CHD, emphysema
  • Genetic: inherited conditions    e.g Cystic firbosis, huntingtons disease 
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digestive system

  • 1st- break down open cells
  • 2nd-hydrolyse till absorbed into blood 

  • proteins- amino acids 
  • carbs- simple sugars 
  • lipids- fatty acids + glycerol 

digestive juices 

  • *Saliva- secreted by glands in mouth 
  • Gastric juice- made by stomach lining 
  • Bile- made by liver 
  • *Pancreatic juice- produced by pancreas             *for unit 1 
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  • e.g : enzymes, antibodies, actin + myosin (muscle contraction) collagen (strength to connective tissues), blood clotting, keratin (strength to hair), in cell membranes 


  • contain C, N, H, O
  • made up of 20 diff. AA 
  • 2 AA join in condensation reaction forming dipeptide 
  • chain of AA is polypeptide which a protein has one or more of 
  • have amino group ---and---carboxylic acid group 
  • globular proteins -- roughly spherical with a chemical funtion in organisms 
  • fibrous proteins -- (collagen + keratin) structural role giving strength/elasticity 
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protein structure

  • primary 
  • sequence of AA in polypeptide 
  • secondary 
  • shape formed when AA bend+twist to form stable arrangement 
  • e.g  a-helix or b-pleated sheet 
  • diff. regions of polypeptide chains have diff. forms of secondary structure 
  • tertiary structure 
  • overall shape of polypeptide chain 
  • bends back on itself -- weak bonds (hydrogen bonds) form so it stabilises 
  • song bonds (disulphide bridges) can form between 2 sulphur containing AA
  • quaternary structure 
  • more than one polypeptide bind to form whole molecule 
  • e.g. insulin (2) haemoglobin (4)
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  • control rate of all metabolic reactions  ---> 
  • metabolism = inter-related chemical reactions taking place inside organism 
  • proteins + catalysts (speed up but not used)
  • speed up reactions by splitting up reaction pathway into small steps that require less ACTIVATION ENERGY - reaction take place more easily + at lower temps. 
  • ACTIVE SITE = matches with SUBSTRATE therefore enzymes are specific 
  • LOCK + KEY = substrate to active site --> ENZYME-SUBSTRATE COMPLEX -->product 
  • INDUCED FIT = active site changes shape so enzyme moulds around substrate 
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temperature and pH affecting enzymes

  • Temp inc. so does ROR until criticla point where enzyme denatured 
  • inc. temp = molecules more KE --> more collisions --> more enzyme-substrate complexes --> ROR inc. 
  • higher temp = vibrates so much --> weak bonds maintaining tertiary structure broken --> shape of molecule changes --> enzyme not work (DENATURED) 


  • enzyme-substrate complex depends upon precise match of SHAPE + CHARGE 
  • pH can change amount of free H+ and OH- ions --> disrupting charges 
  • all enzymes have optimum pH
  • intracellular (inside cells) enzymes work 7.3-7.45 
  • extracellular enzymes (digestive in stomach + s.intestine) work at pH extremes 
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substrate concen. and inhibition affecting enzymes

  • inc. substrate concen. = inc. ROR (until enzymes working as fast as possible) 
  • fast as possible = all active sites used all time (inc by adding more enzymes)


  • inhibitor = slows down or stops enzyme action 
  • most are reversible = not combine with enzyme molecule permanently
  • two type of reversible : competitive + non-competitive 
  • competitive --
  • similar to substrate (3D shape)
  • enter active site --> get in way --> compete with substrate for active site 
  • more substrate = less inhibitor 
  • non-competitive --
  • bind to enzyme away from active site changing tertiary structure 
  • modifies shape of active site --> enzyme-substrate complex cant form 
  • more substrate = no effect on ROR or level of inhibition 
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carbohydrates and their digestion

  • include sugars, starches, celuulose, glycogen 
  • contain elements C, H, O 
  • divided into categories according to size: 
  • MONOSACCHARIDES -- 'single sugars' (glucose, fructose, galactose)
  • DISACCHARIDES -- 'double sugars' (sucrose, maltose, lactose) 
  • POLYSACCHARIDES -- 'multiple sugars' (starch, glycogen, cellulose) 
  • mono. + di. = sugars, sweet, white, water-soluble solids 
  • poly. = polymers of sugars, not sweet or soluble 
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monosaccharides, di. and poly.

  • most common is glucose : a-glucose + b-glucose 
  • diff. forms affect properties of polymers that contain glucose 
  • glucose molecules link by CONDENSATION REACTION producing MALTOSE + one molecule of WATER 
  • two mono. linked by GLYCOSIDIC BOND (C-O-C) + molecules share oxygen atom


  • MALTOSE (GLU. + GLU.)- germinating seeds produced by starch breakdown 
  • SUCROSE (GLU. + FRU.)- transport in carb. plants in phloem 
  • LACTOSE (GLU. + GAL.)- milk in almost all mammals 

polysaccharides - 

  • STARCH (AMYLOSE + AMYLOPECTIN)  - main storage in plants 
  • amylose (single unbranched chains forming spiral of a-glucose) 
  • amylopectin (branched chains of a-glucose) 
  • large molecules (INSOLUBLE), spiral/branched (COMPACT), amylop. many branches so glu. released easily from poly. then amylos. (EASILY CONVERTED TO ENERGY)
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carbohydrate digestion

  • poly. + di. must be digested to mono. before being absorbed 
  • begins in mouth (amylase in saliva hydolyses STARCH to MALTOSE) 
  • doesnt stay for long (hot food denatures + acidic in stomach deactivate salivary amylase) 
  • no significant in stomach 
  • takes place in DUODENUM 
  • pancreatic amylase (starch to maltose) --> enzymes in membranes of epithelial cells ---> folded membrane known as BRUSH BORDER 
  • BRUSH BORDER enzymes = maltase, lactase + sucrase 

lactose intolerance 

  • cannot make lactase to digest lactose 
  • undigested --> used by gut bacteria --> abdominal bloating, pain, diarrhoea, wind 
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biochemical tests for carbs. 

  • reducing sugar -
  •  Benedicts solution - +ve turns BLUE --> RED/ORANGE 
  • QUANTITIVE TEST - higher concen of r.sugar more dark orange + less green --> amount of orange copper oxide compared filter, dry, weigh OR colorimeter 
  • e.g. monosaccharides glu, fru, gal, + disaccharides maltose + lactose 
  • non-reducing sugar 
  • boiling sample -ve from reducing sugar test + HCL+neutralise with sodium hydrogencarbonate 
  • acid hydrolyses sugars to reducing sugars 
  • +ve turns BLUE --> RED/ORANGE 
  • starch 
  • yellow/brown iodine/potassium iodide solution = +ve turns BLUE/BLACK 
  • as iodine fits in spirals of starch molecules forming dark coloured starch/iodine complex 
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