Mutation Flashcards
What is a mutation?
change in DNA base sequence
(random)
When does a point mutation happen?
happens often during DNA replication
What increases the chances of point mutation
radiation - x-rays
chemicals
UV light
Some viruses
What are the types of point mutation?
substitution
insertion
deletion
inversion - bases swapped
What is a frameshift mutation?
changes number of nucleotides so no longer divisible by 3 as translation relies on reading triplet
protein made is significantly different than before as every triplet is changed after mutation so amino acid coded for is different
What are the results of point mutation?
silent mutation
nonsense mutation
missense mutation
What is a silent mutation?
amino acid not changed - degenerate (triplet code for same aa)
What is a nonsense mutation?
amino acid chain abruptly terminated
(triplet codes for aa stop codon)
What is a missense mutation?
change in amino acid - will affect bonding
Why are not all mutations a problem?
amino acid nit changed: degenerate
in introns or non-coding DNA (not gene)
same bonds between amino acids form
mutation not in enzyme of active site (or binding site of protein)
What is a chromosome mutation?
changes in the structure or number of whole chromosomes
or
changes in the whole sets of chromosomes - called polypoidy
- often occurs in plants e.g. may have 3+ sets of chromosomes instead of 2
What is non-disjunction?
changes in number of individual chromosomes (occurs during anaphase - incorrect pulling apart)
chromsomes pulled apart in anaphase I
chromatids pulled apart in anaphase II
What are the examples of non-disjunction?
down syndrome / klinefelter syndrome
