Fundamental Molecular

Question 1

What are mutations?

Answer 1

Mutations are changes in the genetic material of a cell.

Question 2

Natural selection requires genetic differences to be passed on through…

Answer 2

Recombination

Question 3

The rate of spontaneous mutation is low but not zero. How many mutations are there per human child?

Answer 3

There are roughly 200 new mutations per human child. These are known as de Novo mutations and are not found in either parent.

Question 4

Where do de Novo mutations occur?

Answer 4

De Novo mutations occur in the germ line cells.

Question 5

Which are more common: somatic or germ line mutations?

Answer 5

Somatic mutations are much more common but are not passed on to offspring.

Question 6

DNA replication has a very low error rate and most errors are repaired. Any error not repaired leads to…

Answer 6

Net mutation

Question 7

How may net mutation be increased?

Answer 7

Increasing rate of DNA damage which may be caused by radiation, reactive oxygen species and mutagens in burnt food, among others.

Question 8

Why do most mutations have no effect on phenotype?

Answer 8

Most mutations land between exons (on introns).

Question 9

What are silent mutations?

Answer 9

Silent mutations are base changes which do not affect the amino acid encoded.

Question 10

What are missense mutations?

Answer 10

Missense mutations are base changes which change the amino acid being coded. They may be conservative or non conservative depending on the similarity of the new amino acid to the original.

Question 11

What are nonsense mutations?

Answer 11

Nonsense mutations are base changes which lead to a stop codon being encoded.

Question 12

What are frameshift mutations?

Answer 12

Frameshift mutations can be insertions or deletions of base pairs. They act like nonsense mutations.

Question 13

Why do most mutations which fall on important regions still have no effect?

Answer 13

They are recessive, and recessive mutations require a level of inbreeding to affect phenotype.

Question 14

What causes Huntington’s Disease?

Answer 14

An autosomal dominant mutation which affects the HTT gene which codes for the Huntingtin. The mutant allele causes the CAG repeat to get longer (expanded microsatellite).

Question 15

What are orthologs?

Answer 15

Orthologs are genes separated by speciation which have similar, or the same, function.

Question 16

What are paralogs?

Answer 16

Paralogs are genes separated by duplication events and usually have diverged function.

Question 17

What are Variable Numbers of Tandem Repeats and how are they categorised?

Answer 17

VNTRs are repetitive pieces of DNA which can be categorised as either microsatellites (1bp-9bp repeating) or minisatellites (10bp-100bp repeating).

Question 18

What are Copy Number Variants?

Answer 18

CNVs are variations in the number of copies of a specific DNA segment on a chromosome between different individuals.

Question 19

Point mutations and variations are known as variations if they have an allele frequency of <1%. What are they known as if the allele frequency is >1%?

Answer 19

Polymorphism

Question 20

SNPs are classed as rare if they have an allele frequency…

Answer 20

Between 1% and 4.9%

Question 21

SNPs are classed as common if they have an allele frequency…

Answer 21

≥5%

Question 22

For a given biallelic system, the Hardy-Weinberg equation predicts what?

Answer 22

The genotype frequencies in the population which keep the allele frequency constant from one generation to the next.

Question 23

The Hardy-Weinberg equation assumes the population…

Answer 23

Obeys random mating, is homogeneous, has not recently been small, any mutation between alleles is occurring at very low frequency and natural selection is not occurring.

Question 24

What does “p” represent in the Hardy-Weinberg equation?

Answer 24

Allele frequency of A

Question 25

What does “q” represent in the Hardy-Weinberg equation?

Answer 25

Allele frequency of a

Question 26

What does “p²” represent in the Hardy-Weinberg equation?

Answer 26

The frequency of AA homozygotes if no evolution is occurring

Question 27

What does “q²” represent in the Hardy-Weinberg equation?

Answer 27

The frequency of aa homozygotes if no evolution is occurring

Question 28

What does “2pq” represent in the Hardy-Weinberg equation?

Answer 28

The frequency of Aa heterozygotes if no evolution is occurring

Question 29

What is the Hardy-Weinberg equation?

Answer 29

p² + 2pq + q² = 1

Question 30

What does the TAS2R38 gene encode for?

Answer 30

A seven-transmembrane G protein-coupled receptor through which the perception of bitter taste is mediated

Question 31

At what base positions do SNPs occur on the TAS2R38 gene?

Answer 31

145, 785 and 886

Question 32

In taster alleles, a cytosine at position 785 leads to which amino acid being encoded?

Answer 32

Alanine

Question 33

In non-taster alleles, a thymine at position 785 leads to which amino acid being encoded?

Answer 33

Valine

Question 34

Which amino acid makeup is characteristic of a taster?

Answer 34

PAV

Question 35

Which amino acid makeup is characteristic of a non-taster?

Answer 35

AVI

Question 36

In which allele will the Fnu4H1 restriction enzyme make a cut?

Answer 36

Taster allele

Question 37

What is the Fnu4H1 restriction enzyme’s restriction site?

Answer 37

GCNGC