Question 1

Which experimental approach was crucial in defining the molecular nature of the gene using bacteriophage?

Accepted Answer

Genetic complementation test

Question 2

In a genetic complementation test, what does it indicate if two mutations fail to complement each other?

Accepted Answer

The mutations are in the same gene

Question 3

Which of the following best describes the process of transcription in prokaryotes?

Accepted Answer

RNA polymerase binds to the promoter, unwinds DNA, and synthesizes mRNA in the 5' to 3' direction

Question 4

What is the main difference between transcription in eukaryotes and prokaryotes?

Accepted Answer

Eukaryotic mRNA undergoes post-transcriptional modifications such as splicing, 5' capping, and polyadenylation

Question 5

If a single nucleotide is inserted early in the coding region of a gene, what is the most likely consequence?

Accepted Answer

A frameshift mutation, altering the downstream amino acid sequence

Question 6

Which codon serves as the universal start signal for translation?

Accepted Answer

$$\mathrm{AUG}$$

Question 7

A mutation changes the codon $$\mathrm{GGC} ($$glycine) to $$\mathrm{GGA}. $$What is the effect of this mutation?

Accepted Answer

Silent mutation

Question 8

Which of the following best explains why the genetic code is described as 'degenerate'?

Accepted Answer

Most amino acids are encoded by more than one codon

Question 9

During translation, which ribosomal site does the incoming aminoacyl-tRNA first bind to?

Accepted Answer

A site

Question 10

What is the role of tRNA in translation?

Accepted Answer

It brings specific amino acids to the ribosome by matching its anticodon to the mRNA codon

Question 11

Which of the following is a direct result of a nonsense mutation?

Accepted Answer

Premature termination of translation

Question 12

In the context of gene expression, what is the function of the promoter region?

Accepted Answer

It is the DNA sequence where RNA polymerase binds to initiate transcription

Question 13

Why do eukaryotic genes often contain introns?

Accepted Answer

Introns allow for alternative splicing, increasing protein diversity

Question 14

A patient has a mutation in the second position of a codon, changing $$\mathrm{GAA} ($$glutamic acid) to $$\mathrm{GUA} ($$valine). What type of mutation is this?

Accepted Answer

Missense mutation

Question 15

Which of the following best describes the coupling of transcription and translation in prokaryotes?

Accepted Answer

Translation can begin on an mRNA while it is still being transcribed

Question 16

What is the main energy source used for the attachment of an amino acid to its corresponding tRNA?

Accepted Answer

$$\mathrm{ATP}$$

Question 17

A mutation in the gene encoding the enzyme that attaches amino acids to tRNA would most directly affect which process?

Accepted Answer

Translation

Question 18

Which of the following statements about the genetic code is correct?

Accepted Answer

It is nearly universal among all organisms

Question 19

If a prokaryotic mRNA contains multiple ribosome-binding sites and start codons, what is the likely result?

Accepted Answer

It encodes multiple proteins (polycistronic mRNA)

Question 20

Which of the following best explains why point mutations in the third position of a codon are often silent?

Accepted Answer

The genetic code is redundant, so changes in the third base often do not alter the amino acid specified

Lecture 15 (Unit 2) -Gene Structure, Expression, and the Genetic Code: From DNA to Protein

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