Mutations

Question 1

What is a gene mutation?

Answer 1

The alteration of a base in the sequence of bases for one gene.

Question 2

When are mutations more likely to occur?

Answer 2

During interphase of DNA replication.

Question 3

Are mutations spontaneous?

Answer 3

Yes

Question 4

What can increase the frequency of mutations?

Answer 4

Mutagenic Agents.

Question 5

What can mutations cause?

Answer 5

Different amino acid sequences in a polypeptide.

Question 6

What happens if the amino acid sequence changes?

Answer 6

When the protein is modified into the tertiary structure, it’ll form hydrogen and ionic bonds in different places thus folding differently. This’ll result in a different 3D shape and thus a non-functioning protein.

Question 7

What can alterations to the genes result in?

Answer 7

A mutation that causes cancer.

Question 8

What are the two types of mutagenic agents?

Answer 8

Carcinogens
High energy and ionising radiation

Question 9

What are carcinogens?

Answer 9

Chemicals that can alter the structure of DNA and interfere with transcription.

Question 10

What are 3 examples of carcinogens?

Answer 10

Chemicals in tobacco smoke, mustard gas and peroxides.

Question 11

Is UV light ionising?

Answer 11

No but it is still high enough to cause damage and disrupt the structure of DNA.

Question 12

What are types of high energy and ionising radiation?

Answer 12

Alpha and beta particles
X-Ray and Gamma Rays.

Question 13

What are the 6 types of gene mutations?

Answer 13

Addition
Deletion
Substitution
Inversion
Duplication
Translocation

Question 14

What is addition mutation?

Answer 14

One extra base is added to the sequence of DNA.

Question 15

Impact of addition mutation?

Answer 15

All subsequent codons are altered. This is known as a frame shift.

Question 16

What could the altered codons in addition mutation result in?

Answer 16

The altered codons could code for different amino acids and thus result in a different sequence of amino acids resulting in a non-functioning protein.

Question 17

If my original triplets of bases were - TAC TTC AGG TGG, what would the addition mutation look like if Adenine was added after TAC?

Answer 17

TAC ATT CAG GTG G

Question 18

What is deletion mutation?

Answer 18

The deletion of a base in a sequence. This causes a frame shift to the left.

Question 19

What could deletion mutation result in?

Answer 19

A different polypeptide chain and thus a non-functioning protein.

Question 20

If my original triplets of bases were - TAC TTC AGG TGG, what would the deletion mutation look like if Thymine was deleted after TAC?

Answer 20

TAC TCA GGT GG

Question 21

What is substitution mutation?

Answer 21

One base has been changed for a different base but the rest remain the same. Thus no frame shift.

Question 22

Why is there no impact of substitution mutation?

Answer 22

The genetic code is degenerate.

Question 23

If my original triplets of bases were - TAC TTC AGG TGG, what would the substitution mutation look like if Adenine was substituted instead of Thymine after TAC?

Answer 23

TAC ATC AGG TGG

Question 24

What is inversion mutation?

Answer 24

A section of bases detaches from the DNA sequence but when they rejoin, they’re inverted. This results in different amino acids being coded for in this region.

Question 25

If my original triplets of bases were - TAC TTC AGG TGG, what would the inversion mutation look like TTC AGG were inverted?

Answer 25

TAC GGA CTT TGG

Question 26

What is translocation mutation?

Answer 26

A section of bases on one chromosome breaks off and attaches onto a different chromosome.

Question 27

What can translocation mutation cause?

Answer 27

Significant impact on gene expression and thus resulting in a different phenotype.