Chapter 4: 4.5 Types of DNA Mutations Flashcards
When do mutations happen?
Mutations in DNA occur when there is a change in the normal DNA sequence
Define:
Point Mutations
Only one base pair is mutated
How can point mutations arise due to? (4)
- Errors in DNA replication
- Environmental exposure to damaging agents like UV light radiation etc.
- Harmful chemicals/toxins
- Byproducts of normal cell metabolism (e.g. lipid oxidation)
What are the types of point mutations?
- Nonsense Mutation
- Missense Mutation
- Silent Mutation
Define:
Nonsense mutations
A premature stop codon is introduced into a sequence
* E.x. UGC (Cysteine) to UGA (Stop)
Define:
Missense mutations
A change to the amino acid sequence
* E.x. UGC (Cysteine) to UGG (Tryptophan)
Define:
Silent mutations
No change to the amino acid sequence
* E.x. UGC (Cysteine) to UGU (Cysteine)
True or False:
Mutations can be beneficial
True, mutations can be:
* Beneficial
* Benign
* Harmful
Define:
Beneficial mutations
Improves the fitness of an organism (e.g. resistance to a virus, lactose tolerance)
Define:
Benign mutations
Does not change the overall fitness of an organism (e.g. change in eye color or silent mutations)
Define:
Harmful mutations
Negatively impacts the fitness of an organism (e.g. development of diseases like cancer and birth defects)
What’s a mnemonic for nonsense mutations causing stop codons?
STOP the NONSENSE
When a nucleotide is replaced by another, it is called a…
Base substitution
True or False:
Point mutations are most commonly base subsitutions
True
What are the types of base substitutions?
- Transitions
- Transversions
