Mutation
돌연변이(Mutation, 변이)은 nucleotide sequence의 변화를 말한다.
분류
- Point mutations((silent, missense, and nonsense)
- Transition: purine to purine (eg, A to G) or pyrimidine to pyrimidine (eg, C to T).
- Transversion:purine to pyrimidine (eg, A to T) or pyrimidine to purine (eg, C to G).
- Silent mutation: Nucleotide substitution이 있지만 같은 amino acid의 코드; often base change in 3rd position of codon (tRNA wobble).
- Missense mutation: Nucleotide substitution -> 다른 amino acid (called conservative if new amino acid is similar in chemical structure)
- Sickle cell disease(substitution of glutamic acid with valine)
- Nonsense mutation: Nucleotide substitution -> early stop codon. -> usually nonfunctional protein
- Frameshift mutation: Deletion or insertion of a number of nucleotides not divisible by 3 ->misreading of all nucleotides downstream. Protein may be shorter or longer, and its function may be disrupted or altered.
- 기타
- Splice site mutation -> retained intron in the mRNA protein with impaired or altered function.
- Rare cause of cancers, dementia, epilepsy, some types of β-thalassemia.
- Splice site mutation -> retained intron in the mRNA protein with impaired or altered function.