OCR Biology A Module 6 content, specifically on the specification point 6.1.1 [a] from the H420 OCR specification. It covers "Types of Mutations." This can be used as active recall during exam season and generally over the two years in Sixth Form. Notes were collated from the OCR Biology A textbook...
Biology - Question and Answer/Active recall
A-level
OCR Module 6
Chapter 1: Cellular Control
Content:
6.1.1 (a) Types of mutations
6.1.1 (b) Regulatory mechanisms
6.1.1 (c) Homeobox genes
6.1.1 (d) The importance of mitosis and apoptosis
6.1.1 (a) Types of mutations
1. what is a mutation?
o a change in the sequence of base pairs in a DNA molecule that
may result in an altered polypeptide
2. when do mutations not have an affect on us?
o the genetic code is degenerate so several different triplets
often code for the same amino acid. Therefore, the mutation
may not alter the actual polypeptide but only slightly alter the
STRUCTURE, but the function remains the same
o mutations (many) also occur in non-coding parts of the DNA
so have no effect on the amino acid sequence at all
3. what are the three main ways that a mutation in the DNA base
sequence can occur?
o insertion
o deletion
o substitution
o …of one or more nucleotides
4. what is an insertion mutation?
o when a nucleotide is randomly inserted into the DNA
sequence
5. how does an insertion mutation cause change to the DNA sequence?
o it changes the amino acid it would have been coded for by the
original base triplet because a new different triplet of bases is
created
o insertion mutation may also have a knock-on effect by
changing the triplets further on in the DNA sequence
(frameshift mutation)
6. what is a deletion mutation?
o a mutation that occurs when a nucleotide is randomly deleted
from the DNA sequence
7. what are the similarities of insertion and deletion mutation?
o like insertion, a deletion mutation changes the amino acid that
would have originally been coded for
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