Question 1

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

Accepted Answer

Multiple codons can encode the same amino acid, reducing the impact of mutations.

Question 2

During translation, which site on the ribosome is responsible for holding the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 3

A mutation changes the codon UAU (tyrosine) to UAA in an mRNA sequence. What is the most likely consequence of this mutation?

Accepted Answer

Translation will terminate prematurely because UAA is a stop codon.

Question 4

Which of the following best describes the role of tRNA synthetase in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA using ATP.

Question 5

Why is transcriptional regulation considered the most important control point of gene expression in eukaryotes?

Accepted Answer

It determines whether a gene's mRNA is produced, affecting all downstream processes.

Question 6

Which of the following is TRUE about the genetic code in most organisms?

Accepted Answer

It is nearly universal, with only rare exceptions among some species.

Question 7

What is the main advantage for a cell in using RNA as an intermediate molecule to make proteins?

Accepted Answer

It allows for amplification and regulation of gene expression without altering the DNA.

Question 8

If a ribosome is translating an mRNA and encounters a stop codon, what happens next?

Accepted Answer

A release factor binds to the stop codon, causing the polypeptide to be released.

Question 9

Which of the following best describes a 'wobble position' in codon recognition?

Accepted Answer

The third base of a codon can pair with multiple bases in the anticodon, allowing flexibility.

Question 10

Which equation correctly represents the number of possible codons in the genetic code?

Accepted Answer

$$4^3 = 64$

Question 11

A scientist observes that a single mRNA molecule is being translated by several ribosomes at once. What is this structure called, and what is its significance?

Accepted Answer

Polysome; it increases the efficiency of protein synthesis.

Question 12

Which of the following is the correct direction for ribosome movement along mRNA during translation?

Accepted Answer

5' to 3'

Question 13

Which amino acid is always the first to be incorporated during translation in eukaryotes?

Accepted Answer

Methionine

Question 14

Transcription factors regulate gene expression by binding to which regions of eukaryotic genes?

Accepted Answer

Regulatory elements such as enhancers and promoters

Question 15

Which process is responsible for removing introns from pre-mRNA in eukaryotic cells?

Accepted Answer

mRNA processing (splicing)

Question 16

A cell has the same DNA as another cell but expresses different proteins. What is the most likely explanation?

Accepted Answer

Gene expression is regulated differently in each cell type.

Question 17

Which of the following statements about tRNA is FALSE?

Accepted Answer

tRNA directly catalyzes peptide bond formation during translation.

Question 18

Which step in translation involves the formation of a peptide bond between amino acids?

Accepted Answer

Elongation

Question 19

Which of the following is a function of small regulatory RNAs (miRNA and siRNA) in gene expression?

Accepted Answer

They regulate gene expression at multiple levels, often by silencing specific mRNAs.

Question 20

Which of the following best describes the directionality of protein synthesis during translation?

Accepted Answer

From the N-terminus to the C-terminus

From DNA to Protein: Gene Expression and Regulation

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