2.15 DNA Mutations Flashcards
What is a nonsense mutation
When a termination codon has been placed in the middle of the gene that results in premature termination
Many DNA Polymerase have what type of activity to reduce error?
Exonuclease activity that can go in either direction. This helps Proofread.
What mutation is a single amino acid replacement in the protein
Missense mutation
What is a frameshift mutation
The addition or deletion of one or two base pairs
Describe the DNA damage of Mispairing
One mis-paired base will result in complete change of sequence after multiple replications
What type of DNA damage occurs during the lost of the purine base and therefore the nucleotide
Depurination
What type of DNA damage occurs when the structure is completely changed to a different base?
Deamination
What occurs to the DNA during UV damage?
Produces Thymine dimers which are covalent bonds between adjacent pyrimidines particularly Thymine
Name the three strategies of DNA repair
- Direct Reversal
- Base Excision Repair
- Nucleotide Excision Repair
What is the product of the deamination of Adenine
Hypoxanthine
Deamination product of Guanine?
Xanthine
Deamination production of Uracil
Cytosine
Deamination product of Thymine
No deamination
T or F, A number of carcinogens are mutagenic because they add bulky chemical groups to the DNA which distort the molecule
True
Describe Direct Reversal
A methylated base can be demethylated by an enzyme that transfer the methyl group to a cysteine residue within its core
