Mutations Flashcards
What is a mutation?
A change in the sequence of nucleotides
What sorts of things can cause a mutation?
Ionising radiation/free radicals, mutagenic chemicals, transposable elements, infection from viruses (eg HIV), errors in DNA replication etc
What are transposable elements?
Sequences of DNA that move (or jump) from one location in the genome to another
What types of mutations are there?
Substitutions, additions, deletions, frame shift
In single nucleotide change mutations, what is transition?
Change to same type of base (purine to purine, pyrimidine to pyrimidine)
In single nucleotide change mutations, what is transversion?
Change to different type of base (purine to pyrimidine or vice versa)
What is the mutation in sickle cell anemia?
Glutamate to Valine (base substitution missense mutation)
6th amino acid, codon 7 of HBB
What are missense mutations?
A mutation in which a single nucleotide change results in a codon that codes for a different amino acid
What are nonsense mutations?
A mutation in which a sense codon that corresponds to one of the twenty amino acids specified by the genetic code is changed to a chain-terminating codon
What mutations do not have an effect
Silent or neutral mutations
Synonymous mutations
Where do germ line mutations occur?
Eggs or sperm, affecting all cells in the body. These can be passed on to offspring.
What has a build up of somatic mutations in mitochondrial DNA been associated with?
Some forms of cancer, heart disease, Alzheimer disease, Parkinson disease etc
What do insertions and deletions often lead to?
Frame shift
What chromosomal mutations are there?
Deletion, duplication, inversion, translocation, non-disjunction
In general (not a rule), what do recessive and dominant mutations cause in terms of function?
Recessive - loss of function - biochemical pathways
Dominant - Increased function - structural abnormalities
