8.1 - DNA and the structure of proteins Flashcards
What is a mutation?
An alteration to the DNA base sequence. Often arise spontaneously during DNA replication.
What are addition and deletion mutation?
Where one or more nucleotides (bases) are either inserted or deleted from the DNA sequence
Substitution mutation
Where one nucleotide in the DNA sequence is replaced by another
Duplication mutation
Where one or more nucleotides duplicate and repeat
Inversion mutation
When the bases are reversed
Translocation mutation
Where a group of nucleotides become separated from the DNA sequence, and are then inserted into the DNA of a different chromosome.
Which mutations are most likely to have a significant impact and why?
Insertion, deletion, duplicatio, translocation. Because they produce a frameshift, meaning the entire amino acid sequence produced will be different.
Which mutations are most likely to have a smaller impact and why?
Substitution, inversion. Because the only alter one or very few triplets, the amino acid sequence might not be affected due to the degenerate nature of the genetic code.
Is a mutation resulting in a change to the amino acid sequence always harmful?
No; maybe neutral if the resulting change in proein has no effect on the organism. Also maybe beneficial, which is the bass for evolution and natural selection.
What is a mutagenic agent? Give examples of this.
Factors that incease the rate of gene mutation. Chemical mutagens such as alcohol and benzene. Ionising radiation such as UV and x-ray.
