Gene Mutation Flashcards
What is a mutation?
Any change to the quantity or the base sequence of the DNA of an organism
When can mutations be inherited?
Mutations occurring during the formation of gametes may be inherited
What is a gene mutation?
A change to one or more nucleotide bases, or a change in the sequence of the bases in DNA
How does a change in a DNA triplet potentially affect a polypeptide?
It can change the amino acid sequence, which may alter the structure and function of the resulting polypeptide
What are the two main types of gene mutation and when do they typically arise?
Base substitution and base deletion, they spontaneously during DNA replication
What is a substitution mutation?
A gene mutation where one nucleotide is replaced by another with a different base
What is the effect of substituting a base in a DNA triplet?
It may change the codon, leading to a different amino acid in the polypeptide chain
How can a single amino acid change affect a protein?
It can affect the protein’s tertiary structure if the original amino acid was important in forming specific bonds
What is the consequence if the tertiary structure of a protein changes?
The protein may have a different shape and may no longer function properly
How can substitution mutations affect enzymes?
If the active site changes shape, it may no longer bind the substrate or catalyse the reaction
Why do some substitution mutations have no effect?
Some substitution mutations have no effect because of the degenerate nature of the genetic code, some amino acids are coded for by more than one codon
What is a gene mutation by deletion?
It is a mutation where a nucleotide is lsot from the normal DNA sequence
How can the deletion of a single nucleotide affect a gene?
The loss of one nucleotide can often alter the entire amino acid sequence of the polypeptide
Why does a single nucleotide deletion often lead to a completely different polypeptide?
This is because DNA is read in triplets, the deletion of one base shifts all following triplets to the left (causing a frameshift), changing every codon after the mutation
What is the likely consequence of a frameshift caused by deletion?
The resulting polypeptide is unlikely to function correctly due to the altered amino acid sequence
What is a frameshift mutation?
A mutation that changes the reading frame of the DNA sequence, typically caused by insertions or deletions not in multiples of three
