Mutations And Genetic Variants P6 Flashcards
Sometimes the sequence of a DNA base can be changed, what is this called?
Mutations
What does it mean when DNA mutate?
A random change occurs in the DNA, which alters the sequence of bases within the molecule.
What are all genetic variants formed by?
Mutations
List the ways a mutation can change the DNA base sequence.
Insertion
Deletion
Substitution
How does insertion change the base sequence?
A new base is inserted into the DNA sequence where it shouldn’t be.
What affect does insertion have on the amino acids?
Insertions can change more than one amino acid as they have a knock on effect on the bases further on in the sequence.
How does deletion change the base sequence?
A random base is deleted from the DNA base sequence.
How does a deletion change amino acids?
They change the way that the base sequence is read and have knock on effects further down the sequence.
How does substitution change the base sequence?
A random base in the DNA sequence is changed to a different base.
How does a substitution change the amino acid?
Some amino acids are coded for by more than one triplet, so substitution mutations don’t always change the amino acids in a protein. (E.g.the amino acid tyrosine is coded for by TAT and TAC)
See page 6 for information about:
Mutations can affect the proteins an organism makes.
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Explain why a gene mutation may affect the phenotype of an organism (3 marks)
A gene mutation alters the base sequence of DNA in a gene (1 mark), which may affect the order of amino acid in the protein produced (1 mark). This may lead to changes in the structure and function of the protein, which may alter the phenotype (1 mark).
