Question 1

Which statement best describes the 'one gene, one polypeptide' hypothesis as refined from Beadle and Tatum's experiments?

Accepted Answer

Each gene codes for a single polypeptide, but many genes can produce multiple related polypeptides due to alternative splicing.

Question 2

During transcription in eukaryotic cells, which of the following modifications occurs to pre-mRNA before it is exported from the nucleus?

Accepted Answer

Addition of a 5' cap and poly-A tail, and removal of introns.

Question 3

Which enzyme is responsible for synthesizing RNA during transcription?

Accepted Answer

RNA polymerase

Question 4

A mutation changes a DNA base triplet from $$	ext{CAA} ($$which codes for glutamine) to $$	ext{UAA} (a $$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 5

Which of the following best explains why a frameshift mutation can have a more severe effect than a point mutation?

Accepted Answer

Frameshift mutations change the reading frame, potentially altering every amino acid downstream, while point mutations usually affect only one amino acid.

Question 6

Which of the following is NOT a function of tRNA during translation?

Accepted Answer

Catalyzing peptide bond formation between amino acids.

Question 7

In the process of translation, what is the role of the ribosome?

Accepted Answer

It anchors mRNA and catalyzes the formation of peptide bonds between amino acids.

Question 8

Which of the following sequences is most likely to be found in an intron?

Accepted Answer

A non-coding sequence that is removed during RNA processing.

Question 9

A scientist discovers a gene that, through alternative splicing, produces three different polypeptides. Which process allows this to happen?

Accepted Answer

Different combinations of exons are spliced together after introns are removed.

Question 10

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 11

Which of the following is true about the genetic code?

Accepted Answer

Each codon consists of three nucleotides and specifies one amino acid.

Question 12

A mutation in the gene for hemoglobin causes sickle cell anemia. What type of mutation is responsible for this disease?

Accepted Answer

A missense mutation that changes one amino acid in the polypeptide.

Question 13

Which of the following is a possible consequence of errors in protein folding after translation?

Accepted Answer

The protein may clump and cause diseases such as Mad Cow disease.

Question 14

Which of the following statements about mRNA is correct?

Accepted Answer

mRNA is made in the nucleus from a DNA template and directs synthesis of polypeptides.

Question 15

Which of the following best describes the function of ribozymes in RNA processing?

Accepted Answer

They are RNA molecules that catalyze the excision of introns during splicing.

Question 16

Which of the following is a direct result of a base insertion or deletion that is not a multiple of three nucleotides?

Accepted Answer

A frameshift mutation

Question 17

Which of the following is true regarding the role of the promoter in transcription?

Accepted Answer

It is a DNA sequence that signals RNA polymerase to start transcription.

Question 18

Which of the following is NOT a cause of mutation in DNA?

Accepted Answer

Removal of exons during RNA processing

Question 19

During translation, what happens when a ribosome encounters a stop codon on the mRNA?

Accepted Answer

A release factor binds to the stop codon, triggering release of the polypeptide.

Transcription and Translation: Gene Expression and Protein Synthesis

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