Temperate Viruses and Lysogeny in Nature
What is the name of viral DNA when it is integrated into a bacterial chromosome?
Prophage
What determines whether a virus can attach to a particular host cell?
The compatibility between viral attachment proteins and specific receptors on the host cell.
What is the latent period in viral replication?
The time between viral infection of a host cell and the release of new viral particles
What is a temperate virus?
A virus that can follow either the lytic or lysogenic cycle.
What happens to a bacterial cell during the lysogenic cycle?
The bacterial cell survives and divides, copying the viral DNA along with its own DNA
Why can a bacteriophage infect one bacterial strain but not another strain of the same species?
Different strains may have different surface receptors or antiviral defense mechanisms
Name two environmental factors that can reduce viral abundance in aquatic ecosystems
UV radiation and high temperatures. Other examples include unfavorable pH and adsorption to particles
What is burst size?
The average number of new virus particles released from one infected host cell
What environmental factors can trigger a prophage to enter the lytic cycle?
UV radiation, DNA damage, and other cellular stresses
What is the difference between a narrow and a broad host range?
A narrow host range means a virus infects only a limited number of hosts, while a broad host range means it can infect many different hosts.
What is the relationship between viral infection and bacterial mortality?
Viruses infect bacteria and can cause cell lysis, increasing bacterial mortality and releasing cellular contents into the environment
What determines whether a virus can attach to a host cell?
Compatibility between viral attachment proteins and receptors on the host cell
What is lysogenic conversion, and how can it change bacterial characteristics?
It is a process in which genes carried by a prophage give bacteria new characteristics, such as toxin production.
Bacterial defense mechanisms that can prevent bacteriophage infection.
Restriction-modification systems and CRISPR-Cas systems
A bacteriophage population produces 100 new virus particles per milliliter per hour. If the average burst size is 50 viruses per infected cell, how many bacterial cells are lysed per milliliter per hour?
2 bacterial cells per milliliter per hour (100 รท 50 = 2)
Why can lysogeny be an advantageous survival strategy for viruses when suitable host cells are scarce or environmental conditions are unfavorable?
Viral DNA can remain inside the host genome and replicate when the host cell divides, allowing the virus to persist without immediately killing the host
A virus successfully attaches to a bacterial cell, but no new viral particles are produced. Why can this happen?
Attachment alone is not sufficient for infection. The virus may fail to inject its genetic material, replicate its genome, produce proteins, or assemble new particles because of host defense mechanisms or cellular incompatibility
How does viral lysis influence carbon and nutrient cycling in aquatic ecosystems?
Viral lysis releases organic carbon, nitrogen, and phosphorus from bacterial cells into the surrounding water. These substances become available to other microorganisms, supporting nutrient recycling through the microbial loop. This process is called the viral shunt