DNA Mutations and Repairs Flashcards
Mutation
process by which the sequence of base pairs in a DNA molecule is altered
Somatic Mutation
mutation in somatic cells, only affects individual
Germ-line mutation
mutation in germ line, transmitted by gametes to the next generation
Base pair substitutions
one bp replaced by another
Base pair insertions or deletions
1+ bp are added or deleted
Transition
Bp substitution from purine to purine or one pyrimidine to pyrimidine
Transversion
Bp substitution from purine to pyrimidine or vice versa
Missense mutation
causes a change in codon and a different amino acid is inserted into the polypeptide
Nonsense mutation
change from codon that specifies an amino acid to a stop codon
Neutral mutation
change in codon so that a different aa is inserted but the aa substitution doesn’t change the protein function
Silent mutation
change in codon but same aa inserted
Frameshift mutation
Reading frame changes downstream of the mutation
incorrect aa are added
usually non-functional protein
Repair Mechanisms
Enzyme-based repair systems
1.Direct correction: reverses the damage
2. Excision of damaged area and new synthesis of DNA
can read intact info from undamaged strand of DNA
What are the 4 chromosomal mutations?
- Deletion
- Duplication
- Inversion
- Translocation
Deletion
part of the chromosome is missing
Duplication
doubling of a segment of the chromosome
Tandem Duplication
doubling of a segment of a chromosome that is close together
Displaced Duplication
doubling of a segment on a chromosome that is in different locations on the same or different chromosome