8A - Mutations and Gene Expression Flashcards
What is a mutation?
A change to the base sequence of DNA in an organism.
What causes mutations?
Errors during DNA replication.
What can increase the rate of mutation?
Mutagenic agents
What are the different types of mutation?
- Substitution
- Deletion
- Addition
- Duplication
- Inversion
- Translocation
In mutations, what is substitution?
When one or more bases are swapped for another.
e.g. ATGCCT becomes ATTCCT
In mutations, what is deletion?
When one or more bases are removed.
e.g. ATGCCT becomes ATCCT
In mutations, what is addition?
When one or more bases are added.
e.g. ATGCCT becomes ATGACCT
In mutations, what is duplication?
When one or more bases are repeated.
e.g. ATGCCT becomes ATGCCCCT
In mutations, what is inversion?
When a sequence of bases is reversed.
e.g. ATGCCT becomes ACCGTT
In mutations, what is translocation?
When a sequence of bases is moved from one location in the genome to another.
Is translocation always within the same chromosome?
No, it can be between chromosomes too.
How does a mutation cause a protein to be non-functional?
- Mutation is a change in the DNA base sequence
- This may change the amino acids that that DNA codes for
- This means that the amino acid sequence is different
- Therefore, the bonds formed are different, so the tertiary structure is different
- This makes the protein non-functional
Give an example of a mutation causing a genetic disorder.
Cystic fibrosis
Give an example of a mutation increasing the likelihood of developing a cancer.
BRCA1 gene mutations can increase the risk of breast cancer.
What is a hereditary mutation?
A mutation that is passed through gametes to the next generation.
Remember to revise the AS mutation flashcards.
Do it. Also see pgs 194-195.
What are mutagenic agents?
Factors that can increase the rate of DNA mutation.
What are the 3 ways in which mutagenic agents work?
1) Acting as a base
2) Altering bases
3) Changing the structure of DNA
How do some mutagenic agents work by acting as a base?
- Chemicals substitute for a base in DNA replication
* This changes the base sequence
What is the name for mutagenic agents that substitute for a base?
Base analogs
Give an example of a base analog.
- 5-bromouracil
- It can substitute for thymine, but pair with guanine instead
- This effectively changes the DNA base sequence
How do some mutagenic agents work by altering bases?
- Chemicals delete or alter bases
* This changes the DNA base sequence
Give an example of a mutagenic agent that alters bases.
- Alkylating agents
- These add an alkyl group to guanine, which changes the structure so it pairs with thymine (instead of cytosine)
- This changes the effective bass sequence
How do some mutagenic agents work by changing the structure of DNA?
- Radiation changes the structure of DNA
* This causes problems during DNA replication