biology Unit 1 Mr Calver pg 4-15

• 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 

• 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 

• e.g : enzymes, antibodies, actin + myosin (muscle contraction) collagen (strength to connective tissues), blood clotting, keratin (strength to hair), in cell membranes 

structure 

• 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 

• 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)

• 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 

• 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) 

pH

• 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 

• 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)

inhibition 

• 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 

• 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 

• 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

disaccharides 

• 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)

• 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 

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