Question 1

Which experiment provided the first strong evidence that DNA, and not protein, is the genetic material responsible for transformation in bacteria?

Accepted Answer

Oswald Avery's experiment using DNA, RNA, and protein-destroying enzymes

Question 2

A double-stranded DNA molecule is found to contain 18% adenine. According to Chargaff’s rules, what percentage of guanine would you expect to find?

Accepted Answer

$$32\%$$

Question 3

Which of the following best explains why pairing a purine with a pyrimidine in the DNA double helix results in a uniform width?

Accepted Answer

A purine-pyrimidine pair matches the width observed in X-ray diffraction data.

Question 4

Which enzyme is responsible for relieving the strain ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 5

In the Meselson-Stahl experiment, after two rounds of DNA replication in $$^{14}N$$ medium, what was observed?

Accepted Answer

One light band and one hybrid band.

Question 6

Which of the following modifications would most likely increase the transcription of a gene in eukaryotic cells?

Accepted Answer

Acetylation of histone tails

Question 7

A mutation in the gene encoding the trp repressor protein (trpR) results in a nonfunctional repressor. What is the most likely consequence for the trp operon in E. coli?

Accepted Answer

The operon will be permanently active, regardless of tryptophan levels.

Question 8

Which of the following statements about the lac operon is correct?

Accepted Answer

The lac operon is induced when allolactose binds to the repressor, inactivating it.

Question 9

Which of the following best describes the function of general transcription factors in eukaryotic transcription?

Accepted Answer

They are required for the transcription of all protein-coding genes.

Question 10

Which of the following is a direct result of the Central Dogma of molecular biology?

Accepted Answer

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

Question 11

During translation, which site on the ribosome does the initiator tRNA occupy first?

Accepted Answer

P site

Question 12

Which of the following is true regarding Okazaki fragments?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand.

Question 13

Which of the following is NOT a component of the DNA backbone?

Accepted Answer

Nitrogenous base

Question 14

Which of the following best explains why antibiotics can target bacterial ribosomes without harming eukaryotic cells?

Accepted Answer

Bacterial ribosomes have a different molecular composition than eukaryotic ribosomes.

Question 15

Which of the following is a property of the genetic code?

Accepted Answer

It is degenerate, with multiple codons specifying the same amino acid.

Question 16

Which process is responsible for the inheritance of epigenetic traits?

Accepted Answer

Chromatin modifications such as DNA methylation and histone acetylation

Question 17

Which of the following is the correct sequence of events during the elongation phase of translation?

Accepted Answer

Codon recognition, peptide bond formation, translocation

Question 18

Which of the following statements about the directionality of nucleic acid synthesis is correct?

Accepted Answer

DNA and RNA are synthesized in the 5' → 3' direction.

Question 19

Which of the following is a function of the enzyme DNA ligase during DNA replication?

Accepted Answer

Joins Okazaki fragments on the lagging strand

Question 20

Which of the following best describes the role of activator proteins in eukaryotic gene expression?

Accepted Answer

They bind to enhancers and increase the rate of transcription.

Molecular Basis of Inheritance and Regulation of Gene Expression

Study Guide - Practice Questions

Study Guide - Flashcards