Chapter 17 - Viruses
How are viral glycoproteins transported from the endoplasmic reticulum (ER) to the host cell plasma membrane?
Via transport vesicles
How is a virus able to bind and enter a host cell?
Viral surface proteins that bind to receptor molecules on the host cell
What is a temperate phage?
bacteriophages which can choose between a lytic and lysogenic pathway of development (BOFFUM)
What does the H in H1N1 stand for?
hemagglutinin
Function of the capsid?
hold the genetic material
Function of genetic material in viruses?
hold the viral genome
What is a capsomere?
individual protein subunits
In which cycle is a prophage formed?
lysogenic cycle
In which cycle is viral DNA propagated?
lysogenic cycle
What cycle kills the host cell?
lytic cycle
What is a prophage?
when the viral DNA is integrated into the bacterial chromosome into a specific site on the bacterial DNA.
What is the name of the enzyme that the "N" refers to in H1N1
"N" in H1N1 stands for neuraminidase. 9 types of neuraminidase.
Why are pigs, birds, bats, and other animals referred to as viral vectors?
Carry virus from one place to another.
What is known about what triggers a prophage to exit the bacterial genome and initiate the lytic cycle?
It is an environmental signal such as: chemical or high-energy radiation.
What is the function of neuraminidase?
It is an enzyme that helps release new virus particles from infected cells.
What does hemagglutinin do?
It is the protein that helps the virus attach to the host cells. There are 16 types hemagglutinin.
What is the function or purpose of the glycoproteins that extend from the viral envelope?
"lock and key" The function of the viral glycoproteins is to bind to specific receptor molecules on the surface of a host cell.
List three ways in which viral infection can lead to disease symptoms.
(1) Viruses can damage or kill cells by causing the release of hydrolytic enzymes from lysosomes. (2) Some viruses can cause infected cells to produce toxins that lead to disease symptoms. (3)Some viruses have molecular components that are toxic, such a envelope proteins.
What are the three processes in that lead to the emergence of a new viral disease?
(1) small, isolated human populations (2) Crossing the species barrier! (e.g Swine flu) (3) Mutation of existing viruses (e.g COVID-19)
What is a virulent phage?
A phage that reproduces only by a lytic cycle.
What is a phage? bacteriophage?
A virus that infects bacteria
Why do viruses have such a high mutation rate? Why are they so unstable?
RNA viruses have a high mutation rate because RNA polymerase does not correct errors during replication. Some mutations cause viruses to cause disease.
What is the fate of the viral genome after it is released into a host cell?
Uses the host enzymes to replicate the viral genome
What components do all viruses have in common?
- genetic material (DNA/RNA) - capsid (protein coat)
What are two cycles viruses use to replicate?
-lytic -lysogenic
What happens to the viral capsid when the viral genetic material enters the host cell?
The capsid is digested by cellular enzymes and it releases the viral genome.
After the virus enters the host cell, what event leads to the release of viral genome into the cytoplasm of the host cell?
The digestion of the capsid by cellular enzymes releases the viral genome.
What is the fate of the host cell's DNA after the host cell has been infected by the virus?
The host DNA is degraded. Viral enzymes break down the host DNA/bacterial DNA.
When a virus enters the cell, what happens to the host ribosome?
The host ribosome will use the mRNA to make more capsid proteins.
At what stage will the viral proteins and the viral genome self-assemble, before or after the virus leaves the host cell?
The viral proteins and the viral genome will self-assemble before leaving the host cell.
What is the fate of the viral glycoproteins as viral particles are released from the host cell?
They become a part of the viral envelope of the new (baby) viruses.
In which cycle is the host cell destroyed?
the lytic cycle
Scientists estimate that 1/3rd of human diseases originate this way.
via crossing the species barrier! :)