19.1 Mutations and Variation Flashcards
What is a mutation? (1 mark)
A change in the sequence of bases in DNA.
What three things are mutations usually caused by? (3 marks)
Substitution, deletion, insertion.
What is it called when only one nucleotide is affected by the mutation? (1 mark)
A point mutation.
DNA is ………….., this means that if a mutation occurs, it may not affect the way the protein is synthesised because the codon still codes for the same amino acid. (1 mark)
Degenerate
What is a frame shift mutation caused by? (2 marks)
The deletion or addition of a nucleotide to the sequence of bases.
Explain what a frame shift mutation is. (2 marks)
The addition or deletion of a nucleotide shifts the reading frame of the sequence of bases.
This means that every codon after the mutation is affected.
What happens if 3 nucleotides are added/deleted to the base sequence? (2 marks)
No change, because there are 3 nucleotides inactive codon, so the reading frame would not be changed.
However, protein formed is still affected, as a new amino acid has been added.
What is a mutagen? (1 mark)
A chemical, physical, or biological agent which causes mutations.
What do mutagens do? (1 mark)
Increase the rate of mutation in DNA.
What is sickle cell anaemia? (1 mark)
A blood disorder where red blood cells develop abnormally.
Mutations can also affect a whole chromosome, describe 4 ways they can change the chromosome structure. (4 marks)
Deletion- a section breaks off and is lost
Duplication- sections get duplicated
Translocation- a section breaks off and joins another non-homologous chromosome
Inversion- a section breaks off, is reversed, and joins back onto the chromosome
