Question 1

Which property of Taq DNA polymerase makes it especially useful for the Polymerase Chain Reaction (PCR)?

Accepted Answer

It is resistant to high temperatures, allowing repeated heating cycles.

Question 2

During eukaryotic gene expression, what is the primary function of general transcription factors (GTFs)?

Accepted Answer

They bind to promoter regions to help RNA polymerase initiate transcription.

Question 3

A mutation changes a codon from $$	ext{UAC} to$$ $$	ext{UAA} in an $$mRNA sequence. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; introduces a premature stop codon.

Question 4

Which of the following best describes the difference between heterochromatin and euchromatin in eukaryotic cells?

Accepted Answer

Heterochromatin is more condensed and generally transcriptionally inactive.

Question 5

In the Meselson-Stahl experiment, which result provided evidence for the semi-conservative model of DNA replication?

Accepted Answer

After one round of replication, DNA showed a single intermediate band.

Question 6

Which of the following best explains why X-inactivation occurs in female mammals?

Accepted Answer

To balance gene dosage between males (XY) and females (XX).

Question 7

A scientist is studying a gene with the following DNA sequence: $$5'	ext{-ATG GCT TGA-}3'. $$What is the corresponding mRNA sequence transcribed from this DNA (coding strand shown)?

Accepted Answer

$$5'	ext{-AUG GCU UGA-}3'$$

Question 8

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand during DNA replication.

Question 9

A patient has a mutation in the gene encoding histone acetyltransferase. Which of the following is the most likely consequence at the chromatin level?

Accepted Answer

Increased chromatin condensation and decreased gene expression.

Question 10

Which of the following best describes the function of the 5' cap added to eukaryotic mRNA?

Accepted Answer

It facilitates ribosome binding and protects mRNA from degradation.

Question 11

During translation, which site on the ribosome does the incoming aminoacyl-tRNA first bind?

Accepted Answer

A site

Question 12

Which of the following is a key difference between DNA and RNA molecules?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Question 13

A cell is observed to have a high level of mRNA splicing errors. Which process is most likely to be directly affected?

Accepted Answer

Protein synthesis (translation)

Question 14

Which of the following best explains the significance of the 'antiparallel' nature of DNA?

Accepted Answer

It enables complementary base pairing and proper replication.

Question 15

A mutation causes a single nucleotide deletion in the coding region of a gene. What is the most likely effect on the resulting protein?

Accepted Answer

A frameshift, altering all downstream amino acids.

Question 16

Which of the following is a function of the MeCP2 protein in gene regulation?

Accepted Answer

It binds methylated DNA and represses transcription.

Question 17

In a cell cycle experiment, a researcher observes that DNA content doubles during a specific phase. Which phase is this?

Accepted Answer

S phase

Question 18

Which of the following best describes the role of telomerase in eukaryotic cells?

Accepted Answer

It adds repetitive DNA sequences to chromosome ends to prevent shortening.

Question 19

A scientist uses gel electrophoresis to analyze DNA fragments. Which property of DNA allows it to be separated by this technique?

Accepted Answer

DNA is negatively charged and migrates toward the positive electrode.

Question 20

Which of the following best explains why induced pluripotent stem cells (iPSCs) are significant in biomedical research?

Accepted Answer

They are adult cells reprogrammed to an embryonic-like state and can differentiate into many cell types.

Molecular Biology: DNA, RNA, and Chromatin Structure Study Guide

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