Transcript Higher Human Biology - NAB 1 - Revision

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)