Module 6 : Cellular control(mutations and variations) Flashcards
What is a mutation?
If the mutation occurs within a gene , what process can be disrupted?
a change in the sequence of bases in DNA
protein synthesis
Name the 5 different types of mutation
-insertion/deletion
-point/substitution
-nonsense
-missense
-silent
Describe what an insertion/deletion mutation is
This type of mutation alters what , what is this known as?
its when 1 or more nucleotide pairs are inserted or deleted from the base sequence
the nucleotide sequence after the insertion/deletion point
-this is known as FRAME SHIFT
What is a point mutation?
when one base pair is replaced with another
What is a nonsense mutation?
when translation is stopped early giving rise to a shortened polypeptide chain due to the addition of a stop codon earlier in the sequence
What is a missense mutation?
a codon change which results in formation of a different amino acid
What is a silent mutation?
a codon change that does not affect the amino acid sequence produced
How is it possible for a silent mutation to occur?
due to the degenerate nature of the genetic code
(a different codon can code for the same amino acid)
Give an example , apart from a silent mutation , where a mutation would have no effect on an organism
if the mutation occured in a non coding region of DNA
Describe how mutations can have damaging affects on the phenotype of an organism
(2 points)
they can result in particular proteins not being synthesised
can also mean that even if proteins are synthesised they may be non functional due to having a different amino acid sequence
How can mutations be beneficial?
1 point
they can result in synthesis of a protein that results in a useful or advantageous characteristic
Mutations can occur spontaneously during DNA replication , but the rate of mutation can be increased by what?
mutagens
What is a mutagen?
a chemical , physical or biological agent that causes mutations
