8.1 ALTERATION OF DNA Flashcards
When do gene mutations occur?
During DNA replication.
What is an addition mutation?
Inserting extra bases into the DNA chain.
What is the effect of the addition mutation?
Causes a frame shift to the right, so affects all the codons.
- If you add a multiple of 3 bases, no frame shift.
What is the deletion mutation?
Removing bases from the DNA chain.
What is the effect of the deletion mutation?
Causes a frame shift to the left, so affects all the codons.
- If you delete a multiple of 3 bases, no frame shift.
What is the substitution mutation?
Swapping one base for a different one.
What is the effect of the substitution mutation?
- Could form a stop codon, and end the polypeptide formation.
- Could form a codon for a different amino acid.
- Could have no affect due to the degenerate nature of the genetic code.
What is the inversion mutation?
When a few bases are taken out of the sequence, inverted (ie CAG - GAC) and put back.
What is the effect of the inversion mutation?
Will have a different codon so change the amino acid formed.
What is the duplication mutation?
Bases are repeated.
What is the effect of the duplication mutation?
Causes a frame shift right and changes the amino acid sequence.
What is the translocation mutation?
Bases are taken from DNA in genes from a DIFFERENT chromosome, and added to another chromosomes’ DNA.
What is the effect of the translocation mutation?
- Leads to abnormal phenotypes.
- Increases the risk of cancer.
- Can reduce fertility.
What are mutagenic agents?
Increase the mutation rate of DNA in replication.
