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8.3 Translation, Genetic Code, Gene Concept & RNAi — Test 1
Q1. The peptidyl-transferase activity of the ribosome resides in the:✓ 23S rRNA
Q2. Which set of events occurs during the elongation phase of translation?✓ Aminoacyl-tRNA loading, peptide-bond formation and translocation
Q3. The statement that the genetic code is 'degenerate and universal' means:✓ An amino acid may be specified by more than one codon, and the code is largely shared across organisms
Q4. Which of the following is NOT a stop (termination) codon?✓ AGA
Q5. Ribozymes are:✓ RNA molecules that act as enzymes (catalysts)
Q6. The 'one gene–one enzyme' hypothesis was proposed by:✓ Beadle and Tatum
Q7. An auxotroph fails to grow on minimal medium plus precursor A but grows when later intermediate B is supplied (pathway A→B→C). This best supports:✓ The one gene–one enzyme hypothesis
Q8. Beadle and Tatum grouped arginine-requiring Neurospora mutants into three complementation classes, suggesting that:✓ Arginine biosynthesis requires three enzymes (three genes)
Q9. The earliest hint that genes control enzymes came from the study of:✓ Inborn errors of metabolism in humans (Garrod)
Q10. RNA interference (RNAi) is most directly used to:✓ Knock down the expression of a specific gene
Q11. Endogenous miRNAs in animals silence target genes mainly by:✓ Base-pairing with the 3'-UTR of specific mRNAs
Q12. The complex that uses small RNAs to recognise and silence target mRNAs is the:✓ RNA-induced silencing complex (RISC)
Q13. Aminoacyl-tRNA synthetases are responsible for:✓ Charging each tRNA with its correct amino acid
Q14. In the standard genetic code, the usual start codon AUG specifies:✓ Methionine (and serves as the initiation codon)
Q15. The wobble hypothesis explains why:✓ One tRNA can read more than one codon
Q16. Which of the following is NOT a DNA sequence polymorphism?✓ DNA methylation
Q17. A single-nucleotide polymorphism (SNP) is best described as:✓ A common genetic marker (a single-base variant)
Q18. The most common type of variation in the human genome is:✓ Single-nucleotide polymorphisms (SNPs)
Q19. Reverse transcriptase is an enzyme that:✓ Synthesises DNA from an RNA template
Q20. Match each component with its translation role and select the correct option.✓ A-ii, B-i, C-iv, D-iii