Question 1

Which of the following is a possible outcome of the lysogenic cycle?

Accepted Answer

All of the outcomes listed (bacterial cell lysis, prophage formation and propagation, and bacterial fission) are possible in the lysogenic cycle. The specific outcome depends on various factors, such as the type of virus or the condition of the host cell.

Question 2

Transduction is a form of recombination in bacteria that involves______ .

Accepted Answer

Transduction involves the transfer of genetic material between bacteria through bacteriophages, which infect and replicate within bacterial cells. Therefore, the best choice is E: bacteriophages.

Question 3

Which of the following is an episome?

Accepted Answer

Episomes are genetic elements that can integrate into the host chromosome and replicate independently. F factor and temperate phages can both exist as episomes, while lytic phages cannot replicate independently and do not integrate into the host chromosome.

Question 4

Bacteriophages engage in two interactive cycles with bacteria.What are these cycles?

Accepted Answer

Bacteriophages engage in two interactive cycles with bacteria: the lytic cycle and the lysogenic cycle. In the lytic cycle, the virus takes over the host cell's machinery to produce more viral particles until the host cell lyses and releases the new viruses. In the lysogenic cycle, the virus inserts its genetic material into the host cell's DNA, where it may remain dormant for an extended period, replicating along with the host cell's genome, until it is triggered to enter the lytic cycle.

Question 5

Assume that one counted 67 plaques on a bacterial plate where 0.1 ml of a 10^-5dilution of phage was added to bacterial culture.What is the initial concentration of the undiluted phage?

Accepted Answer

To calculate the initial concentration of the undiluted phage, you use the formula: (Number of plaques × dilution factor) / volume plated. Given 67 plaques on a plate with 0.1 ml of a 10^-5 dilution, the calculation is (67 × 10^5) / 0.1 = 6.7 × 10^7 pfu/ml.

Question 6

Which of the following occurs during cell lysis?

Accepted Answer

Cell lysis refers to the bursting open of the host cell caused by the release of newly formed viral particles. Plaque formation is the visible result of cell lysis in a bacterial lawn, where a clear zone is formed due to the lysis of bacteria by the viral particles. None of the other choices relate to cell lysis.

Question 7

What is meant by the term cotransformation?

Accepted Answer

Cotransformation refers to the simultaneous transformation of multiple linked genes. This can occur when multiple genes are located close together on the same DNA fragment, which is then taken up by a recipient cell during transformation. The genes can then become integrated into the recipient cell's genome together.

Question 8

The clearing made by bacteriophages in a "lawn" of bacteria on an agar plate is called a______ .

Accepted Answer

The clearing made by bacteriophages in a "lawn" of bacteria on an agar plate is called a plaque. A plaque is a clear, circular zone that forms on the surface of a bacterial lawn as the result of phage infection, bacterial lysis, and the release of the phage progeny. The other choices do not accurately describe this phenomenon.

Question 9

Temperate phages are those that can enter either the______ or the______ cycle.

Accepted Answer

Temperate phages are able to enter either the lytic or lysogenic cycle, allowing for both replication in the host cell and integration into the host genome. This is in contrast to virulent phages, which are only able to enter the lytic cycle. Choice E (lytic; lysogenic) best describes these two reproductive cycles.

Question 10

Name two forms of recombination in bacteria.

Accepted Answer

Conjugation and transduction are two forms of recombination in bacteria. Conjugation involves the transfer of genetic material through direct cell-to-cell contact via a conjugation pilus, while transduction involves the transfer of genetic material by a bacteriophage. These two mechanisms allow for the exchange of genetic material and the creation of new genetic combinations in bacterial populations.

Question 11

Which of the following statements is false?

Accepted Answer

Lysogeny is a process that can occur during infection by a bacteriophage in which the phage DNA integrates into the bacterial chromosome, forming a prophage. Option A is true as lysogeny leads to a symbiotic relationship between phage and bacterium. Option C is also true as a virulent phage is a type of phage that only undergoes lytic infection. Option D is true as a prophage can exist in a quiescent state in the bacterial chromosome. Option E is false as viral genomes may also include genes for replication, regulation, and host cell interaction.

Question 12

A bacteriophage that is capable of entering either a lytic or a lysogenic cycle is called an______.

Accepted Answer

A bacteriophage that is capable of entering either a lytic or a lysogenic cycle is called a temperate bacteriophage. This is because it can "temper" its behavior based on the conditions within the host bacterium. In the lysogenic cycle, the phage DNA integrates into the host genome and replicates along with the host DNA. In the lytic cycle, the phage DNA immediately begins to replicate and express its genes to produce new virions, causing the bacterium to lyse and release the newly-formed phages.

Question 13

What are the general structural features of a prokaryotic plasmid?

Accepted Answer

Prokaryotic plasmids are small, circular, double-stranded DNA molecules that exist in the cytosol of bacteria. They are separate from the bacterial chromosome and can replicate independently. They often carry genes that provide advantages to the bacterium, such as antibiotic resistance.

Question 14

What is a bacteriophage?

Accepted Answer

A bacteriophage is a type of virus that infects and replicates within bacteria. It uses bacteria as its host to multiply, which distinguishes it from other types of viruses that may infect different kinds of cells.

Question 15

After transformation,heteroduplex formation,and resolution,the resulting daughter cells are______ .

Accepted Answer

The answer of After transformation,heteroduplex formation,and resolution,the resulting daughter cells...

Question 16

What is the first step in phage formation inside the bacterial cell?

Accepted Answer

DNA packaging as the viral heads assemble is the first step in the formation of a phage inside a bacterial cell. This process involves the insertion of viral DNA into the capsid, which is crucial for the formation of new virus particles.

Question 17

When a bacteriophage genome incorporates itself into the chromosome of the host,that phage genome is referred to as an______.

Accepted Answer

When a bacteriophage genome incorporates itself into the chromosome of the host, it is referred to as a prophage.

Question 18

Bacteria that are in a particular physiological state to become transformed are called______ .

Accepted Answer

Bacteria that are in a particular physiological state to become transformed are called competent. It means that they are able to take up DNA from their environment and incorporate it into their genome. Resistant means that they are resistant to certain antibiotics or chemicals. Episomal means that DNA is present in the cell as an episome. Temperate refers to a phage that can enter a lysogenic state.

Question 19

What is a plaque composed of?

Accepted Answer

Plaques are clear zones on bacterial lawns on agar plates, indicating where bacteriophages have lysed the bacteria. They consist of lysed bacteria, the phages that infected them, and the agar medium they are grown on.

Question 20

What is the process by which a temperate bacteriophage infects a bacterial cell and subsequently integrates its chromosome into the bacterial chromosome?

Accepted Answer

Lysogeny is the process by which a temperate bacteriophage infects a bacterial cell and subsequently integrates its chromosome into the bacterial chromosome. During lysogeny, the viral DNA becomes a prophage and is replicated along with the host DNA during cell division. Under certain conditions, such as exposure to UV radiation or certain chemicals, the prophage can be induced to leave the host chromosome and begin the lytic cycle, resulting in production of new viral particles and lysis of the host cell.

Quiz 6: Genetic Analysis and Mapping in Bacteria and Bacteriophages

Which of the following is a possible outcome of the lysogenic cycle?

Transduction is a form of recombination in bacteria that involves______ .

Which of the following is an episome?

Bacteriophages engage in two interactive cycles with bacteria.What are these cycles?

Assume that one counted 67 plaques on a bacterial plate where 0.1 ml of a 10^-5dilution of phage was added to bacterial culture.What is the initial concentration of the undiluted phage?

Which of the following occurs during cell lysis?

What is meant by the term cotransformation?

The clearing made by bacteriophages in a "lawn" of bacteria on an agar plate is called a______ .

Temperate phages are those that can enter either the or the cycle.

Name two forms of recombination in bacteria.

Which of the following statements is false?

A bacteriophage that is capable of entering either a lytic or a lysogenic cycle is called an______.

What are the general structural features of a prokaryotic plasmid?

What is a bacteriophage?

After transformation,heteroduplex formation,and resolution,the resulting daughter cells are______ .

What is the first step in phage formation inside the bacterial cell?

When a bacteriophage genome incorporates itself into the chromosome of the host,that phage genome is referred to as an______.

Bacteria that are in a particular physiological state to become transformed are called______ .

What is a plaque composed of?

What is the process by which a temperate bacteriophage infects a bacterial cell and subsequently integrates its chromosome into the bacterial chromosome?

Quiz 6: Genetic Analysis and Mapping in Bacteria and Bacteriophages

Which of the following is a possible outcome of the lysogenic cycle?

Transduction is a form of recombination in bacteria that involves______ .

Which of the following is an episome?

Bacteriophages engage in two interactive cycles with bacteria.What are these cycles?

Assume that one counted 67 plaques on a bacterial plate where 0.1 ml of a 10-5 dilution of phage was added to bacterial culture.What is the initial concentration of the undiluted phage?

Which of the following occurs during cell lysis?

What is meant by the term cotransformation?

The clearing made by bacteriophages in a "lawn" of bacteria on an agar plate is called a______ .

Temperate phages are those that can enter either the______ or the______ cycle.

Name two forms of recombination in bacteria.

Which of the following statements is false?

A bacteriophage that is capable of entering either a lytic or a lysogenic cycle is called an______.

What are the general structural features of a prokaryotic plasmid?

What is a bacteriophage?

After transformation,heteroduplex formation,and resolution,the resulting daughter cells are______ .

What is the first step in phage formation inside the bacterial cell?

When a bacteriophage genome incorporates itself into the chromosome of the host,that phage genome is referred to as an______.

Bacteria that are in a particular physiological state to become transformed are called______ .

What is a plaque composed of?

What is the process by which a temperate bacteriophage infects a bacterial cell and subsequently integrates its chromosome into the bacterial chromosome?

Assume that one counted 67 plaques on a bacterial plate where 0.1 ml of a 10^-5dilution of phage was added to bacterial culture.What is the initial concentration of the undiluted phage?

Temperate phages are those that can enter either the or the cycle.