Gene Mutation Flashcards
What is a mutation?
A change in the DNA base sequence
Often arise spontaneously during DNA replication
What is a substitution mutation?
One base is changed for a different base
What is an inversion mutation?
A sequence of bases is reversed
What is an addition mutation?
One extra base is added to the sequence
What is a deletion mutation?
Deletion of a base in a sequence
What is a duplication mutation?
One base is duplicated at least once in the sequence
What is a translocation mutation?
When a section of bases on one chromosome detaches and attaches onto a different chromosome
This is a substantial alteration + can cause significant impacts on gene expression and therefore the resulting phenotype
Which mutations are most likely to have significant impact + why?
Addition, deletion, duplication, because they produce a frame shift meaning the entire amino acid sequence produced will be different
Which mutations are more likely to have a smaller impact + why?
Substitution, inversion because they only alter one or very few triplets so the amino acid sequence may not be affected due to the genetic code being degenerate or if the mutation is in the introns, it wouldn’t change the amino acids coded for
What are the consequences of mutation?
Change in the base sequence of amino acids will change the primary structure of a protein which will change the secondary and tertiary structure of the protein as the hydrogen + ionic bonds change so if the protein is an enzyme, the active site will change shape meaning it can no longer form E-S complexes
Is a mutation resulting in a change to the amino acid sequence always harmful?
Not all mutations are negative, positive mutations which give organisms advantages + help them to increase their survival + reproduction rate compared to others in their species can lead to evolution
What is a mutagenic agent?
Physical or chemical factors that increase the rate of gene mutation
E.g. alcohol, tobacco smoke, ionising radiation such as UV + x-rays
