Mutation Flashcards
What is a mutation?
A heritable alteration in a gene or chromosome
What are the three types of mutants?
Name a few
Exogenous
- ionising radiation
- mutagenic chemicals
Endogenous
- DNA replication defects
- transposable elements
Spontaneous events
Not all mutations are damaging
Name two other types of effect
- Neutral
- Adaptive
What does deamination mean?
Loss of an amino acid
What does dimerisation mean?
Formation of a bond between two similar base pairs
What are the two ends of mRNA?
5’ cap
PolyAtail
What is an insertion mutation?
One or more nucleotides are added to a nucleic acid sequence (can be anywhere)
What direction is DNA read in transcription?
Hence, what direction is mRNA synthesised?
3’ to 5’
5’ to 3’
What direction is mRNA read in translation?
5’ to 3’
What is a missense mutation?
A codon replaces one amino acid with another
What is a nonsense mutation?
Changes a codon for an amino acid with a stop codon
What is a frameshift mutation?
Nucleotides other than in multiples of three are added or removed from a nucleic acid sequence
What is chromosomal inversion?
A stretch of chrome is inverted on the same chromosome
What is chromosomal insertion?
A stretch of chromosome from one chromosome is inserted into another chromosome
What is non invasive prenatal testing?
Method used to determine risk of the being born with certain chromosomal abnormalities
Tests analyse small DNA fragments in the blood of a pregnant woman
What are synonymous mutations?
They are neutral - have no effect
What type of mutation is sickle cell anaemia?
Name some symptoms
Autosomal recessive
Infections, weakness, sickle shaped RBC
What is single nucleotide polymorphism?
What are they called when:
- have no effect
- outside gene
- inside gene
A change in a single base pair
Anonymous
Non-coding
Coding
What are the four affects of SNP?
- the sequence of a gene
- the amount of a gene
- the polypeptide length
- no affect
What are non-synonymous mutations?
They change the protein sequences
What are the two types of DNA substitution?
Transition
Transversion
Describe transition substitution
Change to the same type of base
(E.g. purine to purine)
Describe transversion substitution
Change to different base type
Which type of substitution is most likely to cause amino acid substitution?
Transversion
For sickle cell anaemia:
Which codon is mutated?
What gene?
What type of mutation?
7
HBB
Missense base substitution (SNP)
What causes Cri du Chat syndrome?
Deletion of short arm
Chromosome 5
Name some symptoms of Cri du Chat
Low birth weight
Cardiac defects
Microcephaly - smallness of head
Epicanthal fold - skin fold of upper eyelid
What chromosomes are affected in robertsonian translocation?
Acrocentric
13, 14, 15, 21 and 22
