B5.1.7 Flashcards
When does a mutation occur
A mutation occurs when the sequence of DNA bases is altered.
How do mutations occur
They occur spontaneously.
What are substances increasing the chance of a mutation occuring
Ethanol, benzene and ionising radiation can greatly increase the chance of a mutation occurring.
What is genetic variation
A genetic variation is a different version of an allele caused by a change in DNA.
What do all variants arise from
Mutation
What determines the effect it will have on the organism
The position of the mutation in the genotype determines the effect it will have on the organism.
What do mutations influence
most mutations won’t affect an organism’s phenotype. however some mutations may influence an organism’s phenotype.
How are mutations harmful
They can cause cancer as cells grow and divide uncontrollably.
They can cause the production of abnormal protein channels that don’t function properly.
It can cause different shaped protein molecules to be made.
What is DNA split into
It is split into coding and non-coding DNA.
If mutations occur within a gene what happens
DNA bases may be changed added or deleted. This changes the sequence of bases. So the order of mRNA during transcription may be different. The amino acids are assembled in a different order leading to the wrong protein produced or it may fold incorrectly and form a different shape.
An example of a mutation in its gene
If the protein is an enzyme its active site may change shape. There are specific sequences of DNA found in the non coding region of DNA. If a mutation occurs within this sequence the gene may not be transcribed into mRNA. So the protein the gene codes for may not be produced.
