Theme 2D Mutations

Question 1

What are mutations

Answer 1

Changes to nucleic acid sequence (DNA and RNA)

Primary force in evolution where natural selection favours beneficial mutations

More likely to be harmful than beneficial

Question 2

What happens if the gene sequence is altered?

Answer 2

It can change the amino acid sequence of the polypeptide which result in variation of phenotype

Question 3

If the gene sequence is altered, what can be the effect on the phenotype?

Answer 3

It can be harmlesss/neutral, harmful/deleterious, or beneficial/advantageous

Question 4

What are germline mutations?

Answer 4

Mutations that originally occurred in gametes and are therefore heritable

Question 5

Give an example of a germline mutation

Answer 5

A gender influence trait, so a dominant trait that is dependent on gender

example a man’s ring finger is bigger than his index finger

Question 6

What are somatic mutations? What cells do they occur in

Answer 6

These mutations happen in all other cell types, other than gametes meaning, they are not heritable

Occurs in progenitor cells (cells that turn into other cells), and all other daughter cells will express the mutation

Question 7

What are somatic mutations expressed as?

Answer 7

Sectors, so the size of mutation depends on the time of mutation

If the mutation occurs earlier, there’s more sectors of mutation and vise versa

Question 8

Example of a somatic mutation

Answer 8

Cancer tumours

Question 9

What are small scale mutations?
What are the types of small scale mutations?

Answer 9

Changes to one or a few base pairs
Base substitution
Insertion
Deletion
transitions
Tranvsersions

Question 10

What is a base substitution mutation

Answer 10

A single nucleotide change as a result of a point mutation
Example C changes to T

Question 11

What is an insertion mutation?

Answer 11

One or more base pairs, added to the sequence during DNA replication, which results in a frameshift mutation

Question 12

What is a deletion mutation?

Answer 12

One or more base pairs, skipped during DNA replication, which result in a frameshift mutation

Question 13

What is a transition mutation?

Answer 13

Purine to purine (a to g)
or pyrimidine to pyrimidine changes (c to t)

Question 14

What is a transversion mutation?

Answer 14

Purine to pyrimidine (G to C)
Or pyrimidine to purine changes (C to A)

Question 15

What is the effect of point mutations on the amino acid sequence of polypeptides?

Answer 15

You can get missense mutations, nonsense, mutation, silent mutations, or frameshift mutations

Question 16

What is a missense mutation?

Answer 16

Non-synonymous
codon change cause a change in the amino acid

Question 17

What is a nonsense mutation?

Answer 17

A premature stop
The sense codon changes to a stop codon, resulting in a shorter polypeptide

Question 18

What is a silent mutation

Answer 18

Synonymous
Change in codon does not change the amino acid
Because of degeneracy of the genetic code

Question 19

What is a frameshift mutation?

Answer 19

Insertion or deletion of a small number of base pair that alters the open reading frame

Question 20

What is an example of a missense mutation

Answer 20

Sickle cell anemia

the beta haemoglobin gene has a sixth amino acid that changes from Glutamic acid to Valine.

This causes deficiency in oxygen exchange, clogs the arteries, and give circulatory problems.

Question 21

What are large scale, chromosomal mutations?

Answer 21

Deletion
Duplication/amplification
Translocation
Inversion

Question 22

What is a deletion?

Answer 22

Loss of many genes

Question 23

What is duplication/amplification

Answer 23

Increasing genes, so duplicating the region of the chromosome

Question 24

What is translocation

Answer 24

Switching genetic parts from nonhomologous chromosomes
So one chromosome has FGH the other has N, now the first chromosome has N and the other one has FGH

Question 25

What is inversion?

Answer 25

Reversing the orientation of a segment of the chromosome
So if it was EFG, that part is now GFE

Question 26

What is a spontaneous mutation?

Answer 26

A naturally occurring mutation, which is mainly caused by replication errors and spontaneous lesions

Question 27

What are spontaneous lesions

Answer 27

Depurinaton (losing a purine)
Deamination (CH or NH2 is removed so C changes to U)

Question 28

What are induced mutations. What are the different types

Answer 28

Natural or artificial agents or mutagents that causes mutations at higher rate than spontaneous mutation

Mutagens
Base analogs
Chemicals
Damage to bases

Question 29

What do mutagens do

Answer 29

Induce mutations by replacing a base, or altering a base so that it mispairs or damages another base where it can’t pair with any base

Question 30

What do base analogs do

Answer 30

Mimic bases and incorporates itself into DNA, which causes mispairing during DNA replication

Question 31

What do chemicals do during induced mutations

Answer 31

Alter the base structure and causes misparing

Ex. Alakylating agents that warp dna

Question 32

What cause damage to bases during induced mutations

Answer 32

UV light thymine dimers (bulky thymines)
Aflatoxin
B-apurinic sites (a and g disappear

Question 33

What is an allele

Answer 33

One of different forms of a gene (sequence variation) which can cause different phenotypes

Question 34

What are wildtype alleles

Answer 34

Normal form of a gene found in nature, or the standard laboratory strain of the organism

These allele are the frame of reference

Question 35

What are loss of function alleles

Answer 35

Mutations that reduces/eliminate, gene function or expression

Question 36

What are gain of function alleles?

Answer 36

Mutations that enhance gene function/expression or increase relative to wild type

Gene expressed greatly but in wrong places