Alteration of the sequence of bases in DNA can alter the structure of proteins

Question 1

What is a gene mutation and when does it occur?

Answer 1

• An alteration of a base in the sequences of bases for one gene. Occurs during DNA replication (interphase)

Question 2

How do gene mutations occur and what could increase them?

Answer 2

They occur spontaneously and mutagenic agents can increase the mutation rate.

Question 3

What are examples of mutagenic agents?

Answer 3

• High energy ionizing radiation
• Carcinogens
• Both disrupt the structure of DNA

Question 4

What are the 6 types of gene mutations?

Answer 4

Addition, deletion, substitution, inversion, duplication and translocation of bases.

Question 5

What are addition mutations and what do they result in?

Answer 5

• One extra base added to the sequence, this results in a frame shift which results in a different amino acid sequence hence non-functioning protein

Question 6

What are deletion mutations and what do they result in?

Answer 6

The removal of a base in a sequence, this results in a frame shift which results in a different amino acid sequence hence non-functioning protein

Question 7

What are substitution mutations and what do they result in?

Answer 7

One base being replaced by another base, there is no frame shift, since only one codon is being changed, due to degeneracy the codon may still code for the same amino acid.

Question 8

What are inversion mutations and what do they result in?

Answer 8

When section of bases detach from the DNA sequence but when they re-join they are inverted hence this section of the code is from back to front. This results in different amino acids being coded in this region

Question 9

What are translocation mutations and what do they result in?

Answer 9

When a section of bases on one chromosome detaches and attaches onto a different chromosome. This leads to significant effects on the phenotype