mutations

Question 1

define mutation

Answer 1

change in the sequence of bases in DNA

Question 2

define point mutation

Answer 2

when single base pair is altered by mutation

Question 3

define substitution mutation

Answer 3

one base pair is replaced by a different base pair

Question 4

define deletion

Answer 4

when one or more bases is removed from a sequence

Question 5

define insertion

Answer 5

addition of one or more nucleotide base pairs into a DNA sequence

Question 6

define frameshift

Answer 6

mutation caused by insertion/deletion in a DNA sequence - shifts the way the sequence is read
- changes every successive codon from point of mutation

Question 7

define silent mutation

Answer 7

mutations in DNA that do not have an observable effect on organism’s phenotype
- result in same AA coded for / mutation occurs in non-coding DNA region

Question 8

define nonsense mutation

Answer 8

substitution of a single base pair leading to appearance of stop codon
- results in shorted and likely non-functioning protein

Question 9

define missense mutation

Answer 9

where single base pair substitution results in the incorporation of an incorrect AA in the primary structure

Question 10

define gene mutation

Answer 10

affects single gene/section of DNA

Question 11

define chromosome mutation

Answer 11

affects whole chromosome / number of chromosomes within a cell

Question 12

explain why a change in sequence of nucleotides in a gene can affect the function of the protein produced

Answer 12

• causes a change in the codon(s)
• if new codon(s) codes for different aa = change in primary structure of protein
• position & involvement of aa in R group interactions within protein will change - final folding + structure will be different

Question 13

describe how a change in the sequence of nucleotides can have a neutral effect.

Answer 13

• same protein may still be synthesised (degenerate)
• mutation occurs in non-coding DNA
• change doesn’t affect organism function

Question 14

describe how a mutation can have a harmful effect

Answer 14

• proteins are no longer synthesised / non-functional
• can interfere with essential metabolic processes

Question 15

describe how a mutation can have a beneficial effect

Answer 15

• protein synthesised results in new + useful characteristic in phenotype

Question 16

what are 2 examples of beneficial mutations

Answer 16

• mutation in human CSM can lead to HIV not being able to bind + enter cells - immunity to HIV
• ability to digest lactose - present primarily in European populations who were more likely to farm cattle

Question 17

state 3 types of mutagens

Answer 17

• physical
• chemical
• biological

Question 18

give an example of a physical mutagen

Answer 18

ionizing radiation

Question 19

give an example of a chemical mutagen

Answer 19

deaminating agents

Question 20

give 3 examples of biological mutagens

Answer 20

• alkylating agents
• base analogs
• viruses

Question 21

describe deletion as a chromosome mutation

Answer 21

section of chromosome breaks off and is lost within the cell

Question 22

describe duplication as a chromosome mutation

Answer 22

sections of chromosome get duplicated

Question 23

describe translocation as a chromosome mutation

Answer 23

section of one chromosome breaks off and joins another non-homologous chromosome

Question 24

describe inversion as a chromosome mutation

Answer 24

section of chromosome breaks off, is reversed and rejoins chromosome

Question 25

give an example of the effect a substitution chromosome mutation can cause

Answer 25

sickle cell anaemia

Question 26

give an example of the effect an insertion chromosome mutation can have

Answer 26

Huntington’s disease

Question 27

give an example of the effect an deletion chromosome mutation can have

Answer 27

cystic fibrosis