Question 1

Which of the following statements best describes the structure of most bacterial chromosomes?

Accepted Answer

They are circular and usually present as a single copy per cell.

Question 2

A scientist discovers a bacterium with a genome size of 0.1 Mb. Which organism is this genome size most similar to?

Accepted Answer

Nasuia deltocephalinicola

Question 3

What is the primary function of DNA gyrase in prokaryotic cells?

Accepted Answer

To introduce negative supercoils into DNA, aiding in compaction and gene expression

Question 4

Which of the following best explains why prokaryotic transcription and translation are described as 'coupled'?

Accepted Answer

Transcription and translation occur simultaneously in the cytoplasm, allowing rapid protein production.

Question 5

A bacterial cell is found to have multiple plasmids, each carrying different antibiotic resistance genes. What is the most likely consequence if this cell infects a patient and is treated with antibiotics?

Accepted Answer

The cell will survive and may transfer resistance genes to other bacteria, leading to rapid spread of resistance.

Question 6

Which of the following is a key advantage of organizing genes into operons in prokaryotes?

Accepted Answer

It allows for the coordinated expression of functionally related genes under a single promoter.

Question 7

If a prokaryotic cell is rapidly growing, which of the following statements about its DNA replication is correct?

Accepted Answer

Multiple rounds of replication can be initiated before previous rounds are finished, resulting in temporary multiple copies of some genes.

Question 8

Which of the following best describes a plasmid?

Accepted Answer

A circular or linear piece of DNA that replicates independently of the chromosome and often carries beneficial genes.

Question 9

A researcher is studying a gene that is 1,000 base pairs long in E. coli. How many kilobase pairs (kb) does this gene span?

Accepted Answer

$$1,000 \div 1,000 = 1 kb$$

Question 10

Which of the following is NOT a typical feature of prokaryotic genomes compared to eukaryotic genomes?

Accepted Answer

High proportion of non-coding DNA

Question 11

A patient is infected with a bacterial strain carrying an R plasmid. What does the 'R' in R plasmid stand for, and what is its significance?

Accepted Answer

Resistance; it carries genes that confer resistance to antibiotics or heavy metals.

Question 12

Which process allows plasmids to be transferred from one bacterial cell to another, spreading traits such as antibiotic resistance?

Accepted Answer

Conjugation

Question 13

Which of the following is a real-world example of a plasmid-encoded trait that provides a selective advantage?

Accepted Answer

Antibiotic resistance in the presence of antibiotics

Question 14

In the context of gene organization, what is the difference between monocistronic and polycistronic mRNA?

Accepted Answer

Monocistronic mRNA encodes a single protein, while polycistronic mRNA encodes multiple proteins from genes under a single promoter.

Question 15

Which of the following best explains why polysomes are important during bacterial translation?

Accepted Answer

They protect mRNA from degradation by nucleases and increase translation efficiency.

Question 16

A scientist is analyzing the genome of Bacillus thuringiensis. What is a notable feature of this organism's plasmids?

Accepted Answer

They encode proteins toxic to insects, which are used in agriculture.

Question 17

Which of the following statements about supercoiling in prokaryotic chromosomes is correct?

Accepted Answer

Negative supercoiling favors DNA unwinding and initiation of gene expression.

Question 18

If a bacterial cell has a genome size of 4,639,675 base pairs and 4,288 open-reading frames, what is the average size of each gene in base pairs?

Accepted Answer

$$4,639,675 \div 4,288 \approx 1,082 bp$$

Question 19

Which of the following is a reason why prokaryotes can respond rapidly to environmental changes?

Accepted Answer

Transcription and translation are coupled, allowing immediate protein production.

Question 20

Which of the following is NOT a function typically provided by plasmid-encoded genes?

Accepted Answer

Basic cellular metabolism

Structure and Organization of Bacterial Genes and Genomes

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