DNA replication: 1. Was first observed in Darwin’s finches 2. Must be accurate in order to transmit the genome to the next generation 3. Is accurate in germ cells and error prone in somatic cells 4. Must include some errors in order to produce variation
1 and 3
2 and 4
1 only
1 and 2
3 and 4
Photoreactivation
Repairs pyrimidine dimers
Uses UV light and visible light sequentially
Causes a bulge in the DNA helix
Utilises UV light for photolyase activity
Does not occur in humans due to the use of sunscreens
Siamese cats show a range of coat colours on a single individual because:
They are homozygous for a missense mutation in TYR that produces a heat sensitive tyrosinase protein
Coat colour is a polygenic trait with many genotypes possible in the breed
The breed was originally formed by the mating of a pale coat cold-climate cat and a brown coat warm-climate cat
Cats arise from the fusion of 2 or more zygotes causing genetic mosaicism
Frequent somatic mutation occurs in the TYR genes when cats are not kept warm
Microsatellites used as genetic markers because:
They can be assayed by PCR and size separation of the DNA fragment amplified
None of the other answers
They give inconsistent results
They always have high rates of recombination when assayed with visible markers
They are very rare
Genetic maps
In humans are circular, not linear
Cannot be used to make predictions in pedigrees
Can be given in units of cM (centiMorgans)
Have no relationship to genetic recombination
The Hardy-Weinberg Equilibrium always results in:
Constant gene and genotype frequencies from generation to generation
25%, 50%, and 25% as the frequencies of the three genotypes AA, Aa, and aa respectively in all cases
A tendency for the dominant allele to go towards fixation
A reduction in the frequency of heterozygotes
Inbreeding
Changes gene frequencies quickly
Results in a stable frequency of heterozygotes
Results in the frequency of heterozygotes being halved each odd generation
Can only be done in plants, not animals
In a certain human population, colour-blindness is 20X more frequent in males than females. This means that:
9.5% of the females are carriers of the colour-blindness gene
The allele for colour-blindness has a frequency of 0.5
There is selection on this characteristic
Females can not be colourblind
0.25% of the females are not colour-blind
When a population is small, the effect is:
Higher mutation rates
That gene frequencies will change at random over time, and certain alleles may become fixed
Heterozygotes will steadily increase in frequency
That recessive alleles will always disappear
In a population mutation from the A to a allele has a frequency of 0.0001, while the reverse mutation rate is 0.0009. What is the equilibrium frequency of the a allele?
0.1
Two of the other answers (a joke for you all – please do not choose this as the correct answer!)
0
10/11
1.0
