Key area 1.6 Mutations Flashcards
What are mutations?
Mutations are random changes in the genome.
What can mutations result in?
No proteins or an altered protein being synthesised.
What are the 2 types of mutation?
single gene and chromosome structure.
What is a single gene mutation?
The alteration of a single nucleotide in a DNA sequence.
What are the 3 types of single gene mutation?
Substitution, Insertion and deletion.
What happens at a Substitution mutation?
A single nucleotide is removed from a DNA sequence and replaced with another.
What happens at an Insertion mutation?
An extra nucleotide is added into the sequence.
What happens at a Deletion mutation?
A single nucleotide is removed from the sequence.
What single gene mutations result in a frameshift?
Insertion and Deletion.
What is a frameshift mutation?
When the mutation changes the entire DNA sequence after the change, resulting in different codons and different amino acids being produced.
What are the types of Substitution mutation?
Missense, nonsense and splice-site
What happens at a missense Substitution?
One codon changes resulting in a different amino acid being produced.
What happens at a non-sense Substitution?
A normal codon is changed into a stop codon. This causes the premature stop of protein synthesis and creates a polypeptide chain shorter than normal.
What happens at a splice-site Substitution?
During RNA splicing one or more introns are left in the mature transcript.
What are the types of chromosome mutations?
Deletion, Duplication, Translocation and Inversion.
What happens at a Deletion chromosome mutation?
A section of the chromosome is removed.
What happens at a Duplication chromosome mutation?
A section of a chromosome is added to another chromesome from its homologous partner.
What happens at a Translocation chromosome mutation?
A section of a chromosome is added to another chromosome which is not its homologous partner.
What happens at an Inversion chromosome mutation?
A section of a chromosome is reversed.
Why are mutations important?
They are the only source of new alleles in a population.
Are mutations always good?
No- Most are harmful or lethal but the can sometimes be advantagous.
What is gene duplication?
Duplication is when a gene produces a second copy.
What does gene duplication allow?
Potential beneficial mutations to occur in a duplicated gene, where the original gene can still be expressed to produce its protein.
What can gene duplication lead to?
In some cases gene duplication leads to the gain of new functions but in other cases the protein function is lost.
