Topic 8 - Alteration of DNA Bases Flashcards
What is an addition mutation?
One or more bases are added e.g ATGCCT become ATGACCT
What is a deletion mutation?
One or more bases are removed e.g. ATGCCT becomes ATCCT
What is a substitution mutation?
One or more bases are swapped for another e.g. ATGCCT become ATTCCT
What is an inversion mutation?
A sequence of bases is reversed e.g. ATGCCT become ACCGTT
What is a duplication mutation?
One or more bases are repeated e.g. ATGCCT become ATGCCCCT
What is a translocation mutation?
A sequence of bases is moved from one location in the genome to another this could be movement within the same chromosome or movement to a different chromosome.
Why do some gene mutations not result in a change to the encoded amino acid?
Some gene mutations change only one triplet code. Due to the degenerate nature of the genetic code, not all such mutations result in a change to the encoded amino acid.
What type of mutation results in a frame shift?
Some gene mutations change the nature of all base triplets downstream from the mutation, ie. result in a frame shift
What is a mutagenic agent?
Something that increases the rate of mutations.
What are some examples of mutagenic agents?
- Ultraviolet radiation
- Ionising radiation
- Some chemicals and viruses
What are the three ways in which a mutagenic agent can increase the rate of mutation?
1) Acting as a base
2) Altering bases
3) Changing the structure of DNA
How can a mutagenic agent increase mutation through acting as a base?
Chemicals called base analogs can substitute for a base during DNA replication
How can a mutagenic agent increase mutation through altering bases?
Some chemicals can delete or alter bases
How can a mutagenic agent increase mutation through changing the structure of DNA?
Some types of radiation can change the structure of DNA, which causes problems during DNA replication. E.g. UV radiation can cause adjacent thymine bases to pair up together.
