Exam II Microbiology: Chapter 5 Flashcards
A fully formed virus that is able to establish an infection in a host cell
Virion
Protein shell that surrounds the nucleic acid
Capsid
The capsid together with the nucleic acid
Nucleocapsid
Naked viruses consist only of a ___________; no outer membrane
Nucleocapsid
Can be found on naked or enveloped viruses
Spikes
External covering of a nucleocapsid, usually a modified piece of the host’s cell membrane
• Viruses take a piece of the cell membrane when they are released from a host cell.
Envelope
- Single-stranded (ss)
- Double-stranded (ds)
- Linear
- Circular
DNA Viruses
• Double-stranded, but more often single-stranded
must be copied into mRNA before translation can occur
RNA Viruses
Ready for immediate translation (mRNA)
Positive single stranded RNA
Must be copied into mRNA before translation can occur
Negative single stranded RNA
+ ssRNA = ___________
mRNA
Carry their own enzymes to create DNA out of RNA
Retroviruses
What are the two different types of capsids?
- Helical
2. Icosahedral
What capsid structure is rod-shaped?
Helical
What capsid structure is geometric in shape and made of 20 triangular pieces?
Icosahedral
What capsid structure has an icosahedral head and many accessory structures that only infects bacteria and is designed to be able to punch through cell walls?
Complex
What are the general phases of the animal viral replication CYCLE called?
The Lytic Cycle
Viruses cannot bind to cells that lack _________ _________ ___________ ?
compatible virus receptors
The entry of the virus through the plasma membrane (and for some cells the cell wall) and movement into the host cell is what part of the lytic cycle?
Penetration
A condition in which the host chromosome carries viral DNA:
Lysogeny
A virus can invade its host cell only through making an exact fit with a specific host molecule (receptor) on the surface of the cell is what part of the lytic cycle?
Absorption (Attachment)
The release of nucleic acid through break down of capsid into cytoplasm of host cells is what part of the lytic cycle?
Uncoating
Replication and protein production is what part of the lytic cycle?
Synthesis
Which virus enters the host cell’s nucleus and replicates?
DNA viruses
Messenger RNA’s for the viral proteins are made in the nucleus in which virus?
DNA viruses
Viral proteins are made in the host cell cytoplasm in which type of virus?
DNA viruses
Viral DNA enters the nucleus. If it is not already double stranded, host replication enzymes will make it double stranded in:
DNA viruses
In the nucleus, viral genes are transcribed into a messenger RNA using host enzymes in:
DNA viruses
Viral RNA and viral proteins are made in the cytoplasm in:
RNA viruses
____ ______ usually bring in some viral enzymes since host cells are not able to replicate.
RNA viruses
Viral RNA is converted to DNA using reverse transcriptase (a viral enzyme) in:
RNA viruses
Viral DNA can insert into a host chromosome and become latent in:
RNA viruses
Viral DNA can used in transcription and translation to produce viral RNA and viral protein in:
RNA viruses
Virus is put together using “parts” manufactured during the synthesis process of the lytic cycle is called:
Assembly
The virus leaves the host cell by two mechanisms in which process of the lytic cycle?
Release
Which cycle produces a latent infection?
Lysogenic cycle
Spongiform encephalopathies
Mad Cow Disease
Virus-induced damage to the cell that alters its microscopic appearance
Cytopathic Effects (CPEs)
Fusion of multiple host cells into single large cells containing multiple nuclei
Syncytia
“Bacterial eating”
Bacteriophages
Noncellular infectious agents are:
Viruses and Prions
Periodically becomes activated under the influence of various stimuli
• Herpes simplex and herpes zoster viruses
Chronic latent state
Viruses incorporate into the DNA of the host.
• This occurs in the lysogenic cycle of viral infection
• Measles virus
Provirus
When a bacterium acquires a new trait from its temperate phage
Lysogenic conversion
- Isolate and identify viruses in clinical specimens.
- Prepare viruses for vaccines.
- Do detailed research on viral culture, multiplication cycles, genetics, and effects on host cells.
Primary purpose of viral cultivation
Specially bred strains of white mice, rats, hamsters, guinea pigs, and rabbits are the usual choices for:
Viral cultivation
Chicken, duck, and turkey eggs are the most common choices for:
Inoculation
Areas where virus-infected cells have been destroyed and show up as a clear, well-defined patches in the cell sheet:
Plaques
- Infectious proteins
- Agents of spongiform encephalitis infection
- Deposited as long protein fibrils in the brain with no nucleic acid
- Creutzfeldt-Jakob disease in humans
- Bovine spongiform encephalopathy in cows
- Found in many other animals as well
PRIONS
- No immune response by the host (no antibodies)
- Diagnosis by neural tissue biopsy
- Fatal disease
- No treatment
- Infection is by eating contaminated meat or by exposure to the neural tissue of an infected animal
Spongiform encephalopathies (Mad Cow Disease)
What cannot be inactivated by heat or other traditional methods of sterilization?
Prions
Virus-like agents that parasitize plants are called:
Viroids
What type of virus is composed of naked strands of RNA, lacking a capsid or any other type of coating?
Viroids
What is the most common cause of human infections?
Viruses
Most ______ ______ just slow down or prevent growth of the virus. They do not cure or completely eliminate the virus.
anitviral drugs
What are the best approaches, at this time, to preventing viral infections?
Vaccines
Mammalian viruses capable of initiating tumors
Oncoviruses
What cancer does Papillomaviruses (HPV) cause?
Cervical cancer
What cancer does Hepatitis B and Hepatitis C virus cause ?
Liver cancer
What cancer does Epstein-Barr Virus cause?
Lymphomas
What cancer does HIV cause?
Many types of cancer
What cancer does HTLV-1 cause?
T cell leukemia
What cancer does Human Herpes virus 8 cause?
Kaposi’s sarcoma
What cancer does Merkel cell polyomavirus cause?
Skin cancer
