Edexcel IGCSE Biology 3.35B Speciation
Practise explaining how DNA base changes alter mRNA, amino acid sequences, proteins and phenotype in enzyme-based contexts.
- Syllabus
- First assessment 2019
- Course
- Biology 4BI1
Exam points
- explain how a base change can alter mRNA codons, tRNA pairing and amino acid sequence
- link altered amino acids to protein shape, active site change and reduced enzyme activity
- use a given DNA sequence change to explain why a different protein may be produced
3.35B DNA mutations and phenotype question 1
[Maximum number: 5]
Mutation can cause changes in the enzymes produced during protein synthesis.
Explain the different effects that a single base mutation can have on transcription and translation and the production and activity of an enzyme.
An explanation that makes reference to five of the following points:
- transcription makes mRNA / eq
- (mRNA will have) different codons / triplets / (base) sequence / order of bases / eq
- different tRNA binds / different amino acids / different anticodon (on tRNA) / eq
- different sequence of amino acids / order of amino acids / chain of amino acids
- different protein / different polypeptide / different structure of protein / different shape of protein / different enzyme / different enzyme properties / eq
- active site no longer fits substrate / ES complexes cannot form / eq
- may have no effect as same amino acid used / similar amino acid used
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