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Enzymes Enzymes are biological catalysts Catalysts speed up chemical reactions They do this by lowering the energy needed to make the reaction take place Factors affecting the activity of an enzyme Enzyme activity is affected by; 1. Temperature 2. pH 3. Enzyme concentration 4. Substrate concentration 5. Inhibitors High temperatures cause chemical bonds to break – the shape of the active site changes and the substrate can no longer bind to it. The enzyme has been denatured. substrate bound to active site enzyme enzyme denatured 5. Inhibitors An inhibitor is a substance which slows down or stops the activity of an enzyme. There are two types of inhibitor: •Competitive •Non-competitive Comparative effects of increasing substrate concentration in the presence of inhibitors when enzyme concentration is limited Competitive inhibitor – rate Non – competitive inhibitor is of affected by reaction is affected by only, increasing concentration of inhibitor concentrationofofsubstrate inhibitor has andno effect. concentration substrate no inhibitor Rate of reaction competitive inhibitor non-competitive inhibitor Increasing substrate concentration Protein synthesis -- translation The ribosome reads the codons on the mRNA and uses the information to make protein peptide bond amino acid tRNA protein under construction anti-codon GUA codon mRNA ribosome Codes DNA GTCAGGATTCGGACA C A G U C C U A AG C C U G U mRNA G U C A G G AU UC G G A C A tRNA 6C Glucose Respiration glycolysis 3C Pyruvic acid (cytoplasm) 2C Acetyl co-enzyme A 6C Citric acid 4C compound (Tricarboxylic acid) Inside matrix of mitochondrion Hydrogen (picked up by NAD) CO2 ATP (waste product) ATP and Muscle Contraction The following experiment shows that ATP provides the energy for muscle contraction, and not glucose Glass slide Muscle fibres 1% glucose 1% ATP Water (control) Final measurements were taken after 5 minutes to allow time for uptake of the solutions Results Solution Initial length Final length glucose 18mm 18mm 0mm 0 ATP 20mm 18mm 2mm 10% water 21mm 21mm 0mm 0 % increase = ( decrease x 100) Initial length = 2 x 100 20 = 10% decrease % difference Only ATP caused muscle contraction, so it must be ATP that supplies the energy for muscle contraction Ribosomes --where protein is made Protein Secretion Secretion of protein from a cell– is an example Rough endoplasmic reticulum (RER) transports protein Golgi apparatus – packages protein for secretion of Exocytosis. Golgi apparatus Nuclear membrane Ribosomes Rough endoplasmic reticulum The effect of osmosis on red blood cells Burst (Haemolysed) Higher water concentration Same water concentration No change Lower water concentration Shrink + wrinkle (crenated) Antibodies Antibodies are Y-shaped molecules produced by lymphocytes. The function of the receptor sites is to combine with antigens Receptor sites Second response is ; 1.faster 2. more antibodies are made Second injection of vaccine First injection of vaccine Concentration of antibody in blood 0 10 20 30 40 Time (days) 50 60 Genetics The normal human body contains 22 pairs of autosomes In addition, we have 2 sex chromosomes; males = XY females = XX This gives us a total of 46 chromosomes Some individuals may have 45 (Turner’s syndrome), or 47 (Klinefelter’s syndrome / Down’s syndrome) This occurs due to a chromosomal mutation called Non - disjunction Example of a monohybrid cross ; The gene for tongue rolling in humans has two alleles. Roller (R) is dominant over non-roller (r) which is recessive If a woman who is homozygous for tongue rolling marries a man who is homozygous for non-rolling then; P phenotypes genotypes gametes female roller RR X male non-roller X R rr r F1 genotype of children Rr F1 phenotype of children All rollers If a woman who is heterozygous for tongue rolling marries a man who is homozygous for non-rolling then; P phenotypes genotypes gametes F1 genotype of children F1 phenotype of children female roller Rr R+r Rr X X male non-roller rr All r rr 50% are rollers + 50% are non-rollers If both parents are heterozygous then ; P phenotypes genotypes gametes F1 genotype of children F1 phenotype of children female roller X male roller Rr X Rr R+r RR R+r Rr Rr rr 75% are rollers and 25% are non-rollers Line Graphs Always label axes fully, do not abbreviate. Choose a scale that uses as much of the graph paper as possible and allows you to plot the numbers accurately A scale has equal divisions Your scale must extend beyond the line you draw Always label your origin Always join up your points using a ruler Do not extend your line beyond the points given eg .do not draw to 0 if you have not been given a value for 0 50 40 Volume of oxygen produced (cm3) x x x 10 12 14 x 30 x 20 x 10 x 0 x 0 2 4 6 8 Time (minutes)