Mutations Flashcards
Mutations can be caused by
Mutagens (substances such as UV radiation, which damage DNA) or errors during DNA replication. Final base sequence is changed
Point mutation 1
Base substitution - one base has been affected, 3rd amino acid changed from ARG TO TRP
Point mutation 2
Is also substitution, BUT is SILENT MUTATION: change in base sequence codes for same amino acid ARG. DUE TO DEGENERACY OF THE CODE LEADING TO REDUNDANCY
There are __ amino acids and __ triplets/codon
20 amino acid and 64 triplets
This means that an amino acid..
Will have more than one triplet that codes for it
BOTH point 1 or point 2 mutation will have..
NO frameshift (where bases move L TO R in base deletion OR insertion that is not a multiple of three); number of AMINO acids still the same,
NO EFFECT on start and stop codons of both mutations
Point 1 mutation will have..
An affect on the final protein enzyme phenylalanine. Change in amino acid = will impact protein folding, shape AND FUNCTION (will not be a bale to catalyse reaction it has intended)
However, for point 2 mutation (silent mutation)
The amino acid chain folds correctly as intended, same LENGTH OF AMINO ACID,and thus ENZYME FUNCTIONS exactly as if the mutation did not happen
Substitution mutation
Single nucleotide changed = result in a codon that codes for DIFFERENT amino acid
Insertion
Base inserted in base sequence
Deletion
A base removed from DNA sequence
Not all SUBSTITUTION result in new amino acids due to…
Redundancy of the code
Substituted means that
The strand has correct number of bases, stop and start codon not affected and PROTEIN can be MADE
Due to degeneracy (same) of the code..
A silent mutation may code for same amino acid and due to same amino acid the FINAL PROTEIN is correct shape and function
However, a substation mutation can also..
Cause final protein/polypeptide to fold incorrectly so does not catalyse a reaction intended/function affected.
Both insertion and deletion causes…
Frameshift mutation bc CHANGE in number of bases /length of gene (increasing or decreasing) the dna sequence
Adding and removing single bases..
Every codon from the POINT OF MUTATION is affected (reading frameshift)
Reading frameshift affects..
The stop and start codons which affects length of amino acid chain and its structure of folding in final protein
Insertion and deletion affect final protein the most, more than…
Substitution (as it affects one triplet) and THEREFORE one amino acid in polypeptide chain = Change in shape of protein
Insertion and deletion results in..
Amino acids AFTER mutation to be incorrect, folding incorrectly, drastic change in shape = non-functional, STOP AND START CODIN TOO early and terminate too early, causing shorter chain, too late
