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