Question 1

Which of the following best explains why quinolones and coumarins are effective antibacterial agents?

Accepted Answer

They inhibit bacterial DNA gyrase, preventing negative supercoiling and thus blocking DNA replication.

Question 2

A researcher is studying a new drug that specifically inhibits topoisomerase I in bacteria. What is the most likely effect of this drug on bacterial DNA?

Accepted Answer

It will prevent the relaxation of negative supercoils, potentially leading to excessive supercoiling and impaired DNA processes.

Question 3

Which of the following is NOT a feature of eukaryotic chromosomes?

Accepted Answer

They are circular and contain a single origin of replication.

Question 4

Negative supercoiling in bacterial DNA is important because it:

Accepted Answer

Promotes DNA strand separation, facilitating processes like transcription and replication.

Question 5

A mutation in a bacterial cell causes DNA gyrase to lose its function. Which of the following is the most likely consequence?

Accepted Answer

The bacterial chromosome will accumulate positive supercoils, hindering replication and transcription.

Question 6

Which of the following best describes the organization of genes and functional sites on a typical eukaryotic chromosome?

Accepted Answer

Genes are interspersed with repetitive sequences, and each chromosome contains multiple origins of replication, a centromere, and telomeres.

Question 7

Which of the following equations correctly represents the relationship between linking number ($$L$$), twist ($$T$$), and writhe ($$W) in $$DNA topology?

Accepted Answer

$$L = T + W$$

Question 8

A eukaryotic gene is found to be 15,000 base pairs long, but the mature mRNA is only 2,000 base pairs. What is the most likely explanation for this difference?

Accepted Answer

The gene contains large introns that are removed during RNA splicing.

Question 9

Which of the following statements about the centromere is correct?

Accepted Answer

It serves as a recognition site for kinetochore proteins, which are essential for chromosome segregation during cell division.

Question 10

A patient is treated with ciprofloxacin for a bacterial infection. What is the molecular target of this drug, and why does it not harm human cells?

Accepted Answer

Ciprofloxacin targets bacterial DNA gyrase, which is structurally different from eukaryotic topoisomerases, so human cells are unaffected.

Question 11

Which of the following is a key difference between eukaryotic and bacterial chromosomes?

Accepted Answer

Eukaryotic chromosomes are linear and have multiple origins of replication, while bacterial chromosomes are typically circular with a single origin.

Question 12

Which of the following best describes the function of topoisomerase I in bacteria?

Accepted Answer

It relaxes negative supercoils by introducing a transient break in one DNA strand.

Question 13

A scientist observes that a certain eukaryotic chromosome has repetitive sequences near its ends. What is the most likely function of these regions?

Accepted Answer

They are telomeres, which protect chromosome ends from degradation.

Question 14

Which of the following is a direct consequence of negative supercoiling in bacterial DNA?

Accepted Answer

It facilitates the unwinding of DNA strands, making processes like transcription and replication more efficient.

Question 15

Which of the following statements about the structure of eukaryotic chromosomes is correct?

Accepted Answer

Each chromosome contains many origins of replication, a centromere, and telomeres at both ends.

Question 16

A bacterial cell is exposed to a drug that inhibits both DNA gyrase and topoisomerase I. What is the most likely outcome for the cell's DNA topology?

Accepted Answer

The cell will be unable to properly regulate supercoiling, leading to impaired DNA replication and cell death.

Question 17

Which of the following best explains why eukaryotic protein-encoding genes are often much longer than those in bacteria?

Accepted Answer

Eukaryotic genes contain introns, which are noncoding sequences that increase gene length.

Question 18

Which of the following is a function of repetitive sequences commonly found near centromeric and telomeric regions in eukaryotic chromosomes?

Accepted Answer

They contribute to chromosome stability and proper segregation during cell division.

Question 19

A geneticist is comparing the number of origins of replication in yeast and human chromosomes. Which of the following statements is most accurate?

Accepted Answer

Both yeast and human chromosomes have multiple origins of replication, but human chromosomes have more due to their larger size.

Genetics Study Guide: Chromosome Structure and Function

Study Guide - Practice Questions

Study Guide - Flashcards