Mutations

Question 1

Define mutation

Answer 1

Change in DNA which can result in a non functioning protein being formed
Also may provide advantages to the organism

Question 2

What is a gene mutation?

Answer 2

A change to one or more nucleotide bases, or a change in the sequence of the bases in DNA
Can arise spontaneoulsy during DNA replication

Question 3

What makes a random mutation more likely to happen?

Answer 3

Exposure of DNA to mutagenic agents which interfere with DNA replication such as UV light, ionising radiation and chemicals

Question 4

What can a gene mutation result in a DNA sequence?

Answer 4

A base substitution mutation
A base deletion mutation

Question 5

What can cause a base sequence mutation to be silent?

Answer 5

-The new codon( the result of base substitution or deletion) may code for the same amino acid as the previous codon
- This is due to the genetic code being degenerate, more than one codon can code for the same amino acid

Question 6

Why might a base deletion of a DNA sequence be more impactful than substitution

Answer 6

• Base deletions result in a frame shift, as the removal of one base changes all the subsequent codons
• This means more amino acids may be incorrectly coded for meaning the polypeptide chain is completley different

Question 7

What may mutation in chromosome number be caused by?

Answer 7

• Chromosome non disjunction during meosis
• This is when the chromosome or chromatid do not separate equally during anaphase
• This results in a gamete having one fewer chromosome or one more chromosome

Question 8

How can a chromosome mutation result in changes in whole sets of chromsomes?

Answer 8

Occor when organisms have 3 or more sets of chromosomes rather than the usual 2
This is polypioldy often happens in plants

Question 9

Describe what non disjunction means

Answer 9

Chromatids fail to seperate during anaphase
Causing both chromatids to go to one pole of the cell