Mutations

Question 1

what are mutations?

Answer 1

a sudden change in the amount or arrangement of genetic material in a cell

Question 2

what is a gene mutation?

Answer 2

• change in sequence of bases in DNA

Question 3

state two types of gene mutations

Answer 3

• base substitution

- base deletion

Question 4

what is base substitution?

Answer 4

nucleotide is replaced by another

Question 5

how does base substitution affect the amino acid sequence and what consequences can arise?

Answer 5

• some mutations do not affect the sequence due to degenerate nature of genetic code
• however, if the mutation affects the sequence, then mRNA copy is altered - different complementary anticodon of tRNA - so different primary structure so altered tertiary structure will affect the active site. This could produce a non-functional protein

Question 6

what is base deletion?

Answer 6

nucleotide is lost from DNA sequence`

Question 7

what is the effect of deletion?

Answer 7

• causes frameshift
• different amino acid sequence
• polypeptide unlikely to function

Question 8

what can affect the rate of gene mutation?

Answer 8

mutagenic agents increase the rate

Question 9

what is a chromosome mutation

Answer 9

change in the structure or number of whole chromosomes

Question 10

what is the term to explain when there is three or more sets of chromosomes?
- in which organisms does this usually occur?

Answer 10

• polyploidy

- in plants

Question 11

what is the term to explain when a pair of chromosomes fail to separate in meiosis?

Answer 11

non-disjunction

Question 12

give an example of a condition due to non-disjunction

Answer 12

down’s syndrome - gamete has extra chromosome so offspring has extra chromosome (21)

Question 13

will the mutation be inherited in somatic mutation?

Answer 13

no

Question 14

will the mutation be inherited in gametic mutation

Answer 14

yes

- occurs in gomads