D1.3 Mutations and Gene Editing Review (IB Bio SL)

How random are gene mutations?

Mutations can occur anywhere in the genome at random, but certain mutations have a higher probability of occurring than others

What is the most likely mutation to occur?

C --> T

How can bases be changed?

Mutations, which occur randomly

There is no natural way to deliberately change bases

Types of mutations

Substitution, insertion, deletion

Substitution mutation

The substitution of one base with another (example C --> T)

Insertion mutation

A mutation where a/some base(s) is/are inserted into the DNA sequence

Deletion mutation

A mutation where a/some base(s) is/are removed from the DNA sequence

Germ cell

Reproductive cells: Sperm and egg cells

Think: "G" for "genetics"

Somatic cell

Body cell (any cell other than an egg or sperm cell)

Causes of mutations

Errors in DNA replication/repair and exposure to radiation/chemical mutagens

What type of mutations are insertions/deletions most likely to cause?

Frameshift/nonsense mutations

If bases were added/removed in pairs of 3, then there is the possibility of a missense mutation (although nonsense mutations can still occur this way)

What type of mutations can substitutions cause?

Silent, missense, or nonsense mutations, depending on what changed