Mutations

Question 1

What is a mutation?

Answer 1

Change in DNA base sequence caused by mutagens

OR

can occur spontaneously

Question 2

What is a mutagen?

Answer 2

Chemical, physical, or biological agent which causes mutations

Question 3

What are point mutations?

Provide examples:

Answer 3

Affects only one base

Substitutions
Insertions
Deletions

Question 4

What can insertion and deletion lead to in a DNA sequence?

Answer 4

Frameshift mutation
–> disrupts triplet code reading

Question 5

Why might substitution not affect the DNA sequence

Answer 5

Genetic code = degenerate

–> multiple codons code fro 1 particular amino acid.

Make same protein = normal functioning

Question 6

What are the effects of mutations?

Answer 6

No effect (degenerate)

Beneficial (enhanced function of protein)

Damaging (malfunctioning protein made)

Question 7

What are silent mutations?

Answer 7

Have no effect on phenotype of organism

Question 8

What are nonsense mutations?

Answer 8

Codon = stop codon

Results in shortened protein being synthesised —> non-functional.

Question 9

What are missense mutations?

Answer 9

Incorrect amino acid into the primary structure when the protein is synthesised.

The mutation could be silent, beneficial, or harmful.

Question 10

What are chromosomal mutations?

Answer 10

Affect the whole chromosome or number of chromosomes within a cell.

Can be caused by mutagens + normally occur during meiosis.

Question 11

In which ways can chromosomal mutations occur?

Answer 11

Deletion: - part of chromosome

Duplication: section of DNA doubled

Inversion: section of chromosome turned upside down

Translocation: section moved itself from 1 chromosome to another.