enzymes are biological catalysts enzymes catalysts speed up chemical reactions they do this by...
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Enzymes are biological catalysts
Enzymes
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 denaturedenzyme
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
no inhibitor
competitive inhibitor
non-competitive inhibitor
Increasing substrate concentration
Rate of reaction
Comparative effects of increasing substrate concentration in the presence of inhibitors when enzyme concentration is limited
Competitive inhibitor – rate of reaction is affected by
concentration of inhibitor and substrate
Non – competitive inhibitor is affected by concentration of inhibitor only, increasing concentration of substrate
has no effect.
Protein synthesis -- translation
The ribosome reads the codons on the mRNA and uses the information to make protein
ribosome
mRNA
amino acid
tRNA
codon
GUAanti-codon
protein under construction
peptide bond
Codes
G T C A G G A T T C G G A C A
DNA
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
3C Pyruvic acid
2C Acetyl co-enzyme A
4C compound 6C Citric acid
(Tricarboxylic acid)
ATPCO2
Hydrogen
(waste product)
(picked up by NAD)
glycolysis(cytoplasm)
Inside matrix of mitochondrion
Respiration
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
glucose
ATP
water
decrease % difference
Initial length
Final length
18mm
21mm 21mm
18mm
0mm
2mm
0mm 0
0
% increase = ( decrease x 100) Initial length
= 2 x 100 20
= 10%
20mm
18mm
10%
Only ATP caused muscle contraction, so it must be ATP that supplies the energy for muscle contraction
Protein Secretion
Nuclear membraneRough endoplasmic reticulum
Ribosomes
Golgi apparatus
Ribosomes --where protein is madeRough endoplasmic reticulum (RER) – transports proteinGolgi apparatus – packages protein for secretion
Secretion of protein from a cell is an example of Exocytosis.
The effect of osmosis on red blood cells
Same water concentration No change
Lower water concentration
(crenated)
Shrink + wrinkle
Burst(Haemolysed)
Higher water concentration
Antibodies
Antibodies are Y-shaped molecules produced by lymphocytes.
Receptor sites
The function of the receptor sites is to combine with antigens
0 10 20 30 40 50 60
Time (days)
Concentration of antibody in blood
First injection of vaccine
Second injection of vaccine
Second response is ; 1.faster
2. more antibodies are made
Genetics
The normal human body contains 22 pairs of autosomesIn 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 female roller X male non-roller
genotypes RR X rr
gametes R r
F1 genotype of children Rr
All rollersF1 phenotype of children
If a woman who is heterozygous for tongue rolling marries a man who is homozygous for non-rolling then;
P phenotypes female roller X male non-roller
genotypes Rr X rr
gametes R + r All r
F1 genotype of children Rr rr
F1 phenotype of children 50% are rollers + 50% are non-rollers
If both parents are heterozygous then ;
P phenotypes female roller X male roller
genotypes Rr X Rr
gametes R + r R + r
F1 genotype of children
F1 phenotype of children
RR 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 accuratelyA 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
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