A base is removed from the first codon of an mRNA sequence. The original sequence is AUG CCU GAA UUU. The remaining bases are read in groups of three from the same starting point.
The first A is removed. Which statement describes the next three complete codons?
CCU, GAA and UUU; all three retain their original positions.
UGC, CCU and GAA; only the first differs from the original codons.
UGC, CUG and UUU; only the first two differ from the original codons.
UGC, CUG and AAU; all three differ from the original codons.
44 exam-style questions on Edexcel GCSE Biology 3.2 DNA and protein synthesis, covering 3.2.1 DNA structure as a polymer, 3.2.2 Genome and gene definitions, 3.2.3 Extracting DNA from fruit, 3.2.4 Base order determines protein shape, 3.2.5 Stages of protein synthesis, 3.2.6 Non-coding DNA variants affecting phenotype, and 3.2.7 Coding DNA variants affecting phenotype. Each one has a worked solution and a mark scheme showing where the marks go.