Mutations Flashcards
What is a mutation?
A heritable alteration in a gene or sequence
Mutations can arise through either _________ or _______ sources
Endogenous
Exogenous
Give examples of exogenous causes of mutations
Ionising radiation
Anti-cancer agents
Mutagenic chemicals
Where does the majority of ionising radiation come from?
Natural sources e.g. Radon gas
What are two endogenous causes of mutations?
DNA replication defects
Transposable elements
What are transposable elements? How can this result in a mutation?
Specific DNA sequences which act as ‘jumping genes’ and move as a unit to random sites
It could result in the transposable element placing itself into the sequence of an active gene and changing its sequence and thus inactivating it
What are micro mutations?
Single base mutations e.g. Insertion, deletion, substitution
What are macro mutations?
Concerning dna sequences or whole genes
Can be insertions, substitutions, deletions or translocations
A single nucleotide change can either be a transition or a transversion, what is the difference between the two?
Transition = change to the same type of base (e.g. Purine to purine)
Transversion = change to a different type of base (purine to pyrimidine)
Sickle cell anaemia is as result of which base change? And therefore which amino acid change?
A to T
Glutamate to valine
Which codon and amino acid is mutated in sickle cell anaemia?
Codon 7
Amino acid 6
What is a missense mutation?
Where a base change results in a change of amino acid
What is a natural/silent/synonymous mutation?
Where a single base mutation results in the sam amino acid and same phenotype being produced
Which single nucleotide changes can affect the polypeptide length?
Additions or deletions (frameshift mutations)
Mutations of the stop codon
Nonsense mutation
What is a nonsense mutation?
Where a single base change results in a stop codon being formed
