Question 1

Which experiment provided evidence that DNA replication is semiconservative, and what was the key finding?

Accepted Answer

The Meselson-Stahl experiment; it demonstrated that after one round of replication, DNA molecules consisted of one old and one new strand.

Question 2

During DNA replication in eukaryotes, which enzyme is responsible for synthesizing the RNA primer, and why is this primer necessary?

Accepted Answer

Primase; because DNA polymerases require a free 3' hydroxyl group to begin synthesis.

Question 3

A mutation changes a codon from UAU to UAA. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; it introduces a premature stop codon, likely truncating the protein.

Question 4

Which of the following best describes the function of the lac operon in E. coli?

Accepted Answer

It enables the bacterium to metabolize lactose only when glucose is absent and lactose is present.

Question 5

Which process is responsible for the removal of introns from pre-mRNA in eukaryotic cells?

Accepted Answer

RNA splicing

Question 6

A patient is diagnosed with a genetic disorder caused by a single nucleotide substitution that does not alter the amino acid sequence of the protein. What type of mutation is this?

Accepted Answer

Silent mutation

Question 7

Which of the following statements about prokaryotic and eukaryotic gene expression is correct?

Accepted Answer

In prokaryotes, transcription and translation can occur simultaneously.

Question 8

Which technique would be most appropriate for amplifying a specific DNA sequence from a small sample, such as in forensic analysis?

Accepted Answer

Polymerase Chain Reaction (PCR)

Question 9

A researcher wants to determine whether a gene is being expressed in a particular tissue. Which technique should they use?

Accepted Answer

Reverse transcription followed by PCR (RT-PCR) to detect mRNA

Question 10

Which of the following best explains why mutations in tumor suppressor genes can lead to cancer?

Accepted Answer

They cause uncontrolled cell division by removing inhibitory signals.

Question 11

Which of the following is a key difference between DNA replication in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes have multiple origins of replication, while prokaryotes typically have a single origin.

Question 12

A scientist introduces a mutation that deletes three nucleotides from the middle of a gene. What is the most likely effect on the resulting protein?

Accepted Answer

A single amino acid is deleted, but the reading frame is preserved.

Question 13

Which of the following best describes the role of tRNA during translation?

Accepted Answer

tRNA carries amino acids to the ribosome and matches its anticodon to the mRNA codon.

Question 14

Which of the following is a function of the CRISPR-Cas9 system in biotechnology?

Accepted Answer

Editing specific genes within an organism's genome

Question 15

In the context of gene regulation, what is the primary function of an operon in prokaryotes?

Accepted Answer

To coordinate the expression of multiple related genes under a single promoter

Question 16

Which of the following best describes the difference between a missense and a nonsense mutation?

Accepted Answer

A missense mutation changes an amino acid, while a nonsense mutation introduces a stop codon.

Question 17

Which of the following is a direct result of alternative splicing in eukaryotic cells?

Accepted Answer

Production of multiple protein isoforms from a single gene

Question 18

A researcher is studying a eukaryotic gene that is only expressed in liver cells. Which mechanism most likely explains this tissue-specific expression?

Accepted Answer

Liver cells contain specific transcription factors that activate the gene.

Question 19

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

Accepted Answer

Multiple codons can specify the same amino acid.

Question 20

A patient’s cancer cells are found to have a mutation in a proto-oncogene. What is the most likely effect of this mutation?

Accepted Answer

The gene product promotes uncontrolled cell division.

BIOL 190A 1001 Final Exam Study Guide: Molecular Genetics, Gene Expression, and Genomics

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