Unit 1 Topic 6 Flashcards
(28 cards)
What are three types of single gene mutations?
substitution
insertion
deletion
What is a substitution mutation?
a substitution mutation means that one nucleotide is substituted for another and an incorrect amino acid may be inserted into a protein
Give an example of a major problem that can be the result of a substitution mutation
sickle cell anaemia
however, usually these changes are minor
What is an insertion mutation?
the addition of one or more nucleotides into a section of DNA
What does an insertion lead to?
all subsequent triplets are read incorrectly therefore the protein made is likely to have many different amino acids and may not work at all
What is a deletion mutation?
a deletion mutation refers to the removal of one or more nucleotides from the DNA
What is the result of a deletion mutation?
a deletion mutation alters the pattern of base triplets in the DNA. This means that deletions of one or two nucleotides are likely to cause drastic changes to a protein
What can both insertion and deletion mutations be known as?
frame shift mutations
What does the effect of a mutation depend on?
its type and location
What happens to a protein if it does not have the correct sequence of amino acids?
it doesn’t function properly
What are three effects of a substitution mutation?
missense
nonsense
splice site mutations
what is a missense mutation?
a missense mutation results in a single incorrect amino acid being inserted into a protein
how bad is the effect of a missense mutation?
the effect the altered amino acid has on the function of the protein will vary depending on its location and chemical properties. this can result in abnormally short protein which may not function properly
what is a splice site mutation
splice-site mutations result in some introns being retained and/or some exams not being included in the mature transcript and may result in a non-functional protein.
What can splice site mutations alter?
post-transcriptional processing
What do nucleotide insertions and deletions result in?
frame-shift mutations
What usually has a greater effect and why:
insertions and deletions or substitutions
insertions and deletions because they result in frame-shift mutations
what is mRNA read in?
groups of three
(codons)
what makes an insertion/deletion mutation have a worse effect?
if the mutation occurs early in the sequence as more codons will be changed
what also happens as a result from frameshift mutations?
the stop sequence will become misplaced which could result in the polypeptide being either too long or too short
what can substitution cause which would make the polypeptide too short?
a premature stop codon
what are four types of chromosome structure mutations?
translocation
deletion
duplication
inversion
what is a translocation mutation?
a section of a chromosome is added to another chromosome, not it’s homologous partner
what is a deletion mutation in chromosome structure mutations?
a section of a chromosome is removed
