Viruses Flashcards
Why aren’t viruses considered living?
- don’t respond to stimuli
- do not consist of cells
- no homeostasis
- no metabolism
Are viruses cellular or non cellular?
non cellular
Name the 2 things that make up a virus
capsid, fiber proteins
Is a virus or cell smaller?
a virus is smaller than a cell
How do viruses reproduce
lytic cycle/lysogenic
What protective covering is around the capsid of some viruses?
envelope
Outside of host cells, viruses are ________
dormant
Do viruses have ribosomes like cells?
no
Do viruses have enzymes like cells?
yes
Viruses use the ____, ____, and ____ of its host cells to be able to reproduce
mRNA, rRna, and tRna
Name a type of cancer thought to be caused by viruses.
HPV
What virus cause blisters that may appear around the mouth
herpes
What virus is responsible for the common cold?
influenza, rhinoviruses
What virus causes warts?
HPV
what is a bacteriophage?
a virus that parasitizes a bacterium by infecting it and reproducing inside it
What is the only part of the bacteria that actually enters the host cell of a bacterium?
Capsid
What nucleic acid do retroviruses contain?
RNA
What enzyme to retroviruses contain that let them make DNA from RNA?
RNA-dependent DNA polymerase
What 2 things do retroviruses inject into their host cell when they attack them?
RNA and Reverse-transcriptase
Give an example of a retrovirus
HIV
What is a viroid?
small circular RNA molecules
without a protein coat
Prions are infectious pieces of _________.
PrP (a protein)
How do prions occur?
Most cases of prion disease arise spontaneously. More rarely prion disease is inherited due to a faulty gene, or acquired by medical procedures, transfusions, or contaminated food.
What happens when prions get into the brain?
causes “holes” in the brain (cause neurons to rapidly degenerate)
Viruses are host specific. What does this mean?
A host specific virus is one which can affect only one kind of host.
Do the viruses that attack most animals also attack most humans?
no
What is meant by cell lysis?
Cell lysis is a common outcome of viral infection. It consists of a disruption of cellular membranes, leading to cell death and the release of cytoplasmic compounds in the extracellular space.
What are latent viruses?
dormant
How long can latent viruses remain inactive?
years
What activates latent viruses?
an external signal
Example of latent virus?
Herpes Virus
During the lysogenic cycle of a virus, what happens to the viral nucleic acid after it is injected into the host cell?
Viral acids form a circle in the center of the cell. The cell then mistakenly copies the viral acids instead of its own nucleic acids. Then the viral DNA organize themselves as viruses inside the cell. When the number of viruses inside becomes too much for the cell to hold, the membrane splits and the viruses are free to infect other cells.
What is a prophage?
the genetic material of a bacteriophage
What causes the phage or viral DNA to start replicating?
????
Viral DNA along with the cell DNA is replicated during each ______ _______
binary fission
One a prophage is active, the host cell is ____ making the virus deadly (or _____)
infected;virulent
Genital herpes is called ________ ____ _
Herpes type 1
Oral herpes is called _______ _____ _
Herpes Type 2
How long does the herpes infection last?
lifetime
Viruses make us sick because they _____ healthy hosts.
destroy
Do antibiotics “kill” a virus?
no
Besides our own immune systems, what can be done to prevent getting some viruses?
vaccines, safe sex, sanitation
