Mutations Flashcards
What is a gene mutation?
The alteration of a base in the sequence of bases for one gene.
When are mutations more likely to occur?
During interphase of DNA replication.
Are mutations spontaneous?
Yes
What can increase the frequency of mutations?
Mutagenic Agents.
What can mutations cause?
Different amino acid sequences in a polypeptide.
What happens if the amino acid sequence changes?
When the protein is modified into the tertiary structure, it’ll form hydrogen and ionic bonds in different places thus folding differently. This’ll result in a different 3D shape and thus a non-functioning protein.
What can alterations to the genes result in?
A mutation that causes cancer.
What are the two types of mutagenic agents?
Carcinogens
High energy and ionising radiation
What are carcinogens?
Chemicals that can alter the structure of DNA and interfere with transcription.
What are 3 examples of carcinogens?
Chemicals in tobacco smoke, mustard gas and peroxides.
Is UV light ionising?
No but it is still high enough to cause damage and disrupt the structure of DNA.
What are types of high energy and ionising radiation?
Alpha and beta particles
X-Ray and Gamma Rays.
What are the 6 types of gene mutations?
Addition
Deletion
Substitution
Inversion
Duplication
Translocation
What is addition mutation?
One extra base is added to the sequence of DNA.
Impact of addition mutation?
All subsequent codons are altered. This is known as a frame shift.
What could the altered codons in addition mutation result in?
The altered codons could code for different amino acids and thus result in a different sequence of amino acids resulting in a non-functioning protein.
If my original triplets of bases were - TAC TTC AGG TGG, what would the addition mutation look like if Adenine was added after TAC?
TAC ATT CAG GTG G
What is deletion mutation?
The deletion of a base in a sequence. This causes a frame shift to the left.
What could deletion mutation result in?
A different polypeptide chain and thus a non-functioning protein.
If my original triplets of bases were - TAC TTC AGG TGG, what would the deletion mutation look like if Thymine was deleted after TAC?
TAC TCA GGT GG
What is substitution mutation?
One base has been changed for a different base but the rest remain the same. Thus no frame shift.
Why is there no impact of substitution mutation?
The genetic code is degenerate.
If my original triplets of bases were - TAC TTC AGG TGG, what would the substitution mutation look like if Adenine was substituted instead of Thymine after TAC?
TAC ATC AGG TGG
What is inversion mutation?
A section of bases detaches from the DNA sequence but when they rejoin, they’re inverted. This results in different amino acids being coded for in this region.
If my original triplets of bases were - TAC TTC AGG TGG, what would the inversion mutation look like TTC AGG were inverted?
TAC GGA CTT TGG
What is translocation mutation?
A section of bases on one chromosome breaks off and attaches onto a different chromosome.
What can translocation mutation cause?
Significant impact on gene expression and thus resulting in a different phenotype.
