Ch 24
Do viruses have a cytoplasm, mitochondria, and ribosomes?
no
proto-oncogene
Normal genes that promote cell division.
What is a vaccine?
A substance introduced into the body to stimulate the production of chemicals that destroy specific viruses or bacteria
lysogenic cycle
A viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA
retrovirus
A virus that enters a host cell and changes its RNA to a proviral DNA replica.
bacteriophage
A virus that infects bacteria
What allows viruses to spread so fast from country to country in modern times?
Air Travel
What is not a vector of viral diseases?
Prions
Scientists began to study viruses because they
could not be seen but caused diseases
Viruses reproduce
in only living cells
animal viruses often infect only specific host cells because
the host cell might have specific receptors for proteins on the virus surface
virulent
virus that replicates only by the lytic cycle
reverse transcriptase
- an enzyme that synthesize DNA instead of RN
lysis
- swelling of cells that eventually bursts, disintegration of cells
How does an RNA virus get viral DNA into a host cell's genome?
-RNA gets released into the host cell -RNA is transcripted into DNA by reverse transcriptase -DNA is integrated into the host cell's genome
envelope
A membranelike layer that covers the capsids of some viruses.
Virus
A nonliving, intracellular parasite. Viruses are typically just pieces of nucleic aid surrounded by a protein coat.
prophage
A phage genome that has been inserted into a specific site on the bacterial chromosome.
Viroid
A strand of RNA or DNA that lacks the protein capsid
vaccine
A substance prepared from killed or weakened pathogens and introduced into a body to produce immunity.
lytic cycle
A type of viral replication cycle resulting in the release of new viruses by lysis (breaking open) of the host cell.
Prions
An infectious form of protein that may multiply by converting related proteins to more prions
What describes what is happening
Bacteriophage attacking a bacterial cell
How does structure and function of bacteriophages make these viruses useful tools for genetic engineering?
Bacteriophages are very good at injecting foreign DNA into bacteria. Genetic Engineers use them to introduce DNA of interest to humans in bacteria
oncogenes
Cancer-causing genes that are formed due to mutations
protease inhibitors
HIV antiviral class known to have severe drug interactions by causing inhibition of metabolism
provirus
Integrated viral DNA
Why would a drug that blocks DNA transcription not be a desirable method for treating a viral disease?
It would block transcription of the host cell's genes as well as viral genes.
capsid
Outer protein coat of a virus
The instructions for making new copies of a virus are coded in
RNA or DNA
Viruses that contain RNA as their genetic material are called
Retroviruses
What substance does a retrovirus use to force their host cells to transcribe DNA form an RNA template
Reverse Transcriptase
Why must a person receive a different flu vaccination each year to be protected against the flu?
The flu virus mutates quickly making new strands - the flu vaccine targets a different strand every year
why are viruses not considered to be living organisms?
They do not have all the characteristics of life
What did Wendell Stanley's work suggest about the nature of viruses?
Viruses were chemicals rather than tiny cells
inactivated virus
a virus that is not able to replicate in a host.
temperate virus
a virus whose replication includes the lysogenic cycle
Attenuated Virus
a weakened form of the virus that cannot cause disease
Describe the structure of ABCD&E
a-protein coat b-RNA c-envelope d-glycoprotein e-reverse transcriptase
antibiotics are ineffective against viral infections because
antibiotics interfere in cellular processes that viruses do not preform
vector
any agent that can put foreign dna into something
A lyctic infection concludes with the
bursting of the host cell
The outer protein coat of a virus is called a
capsid
emerging disease
disease that appears in the population for the first time, or an old disease that suddenly becomes harder to control
unlike lyctic viruses, lysogenic viruses do not...
lyse the host cell right away
In which cell cycle does viral dna become integrated into the host cell's DNA
lysogenic
Name 4 viruses that can cause disease and can be fatal?
rabies, smallpox, HIV, and Ebola
What kind of factors can cause a prophage to become a virulent?
radiation and certain chemicals
If viruses aren't living, why are they studied in biology?
some scientists (biologists) believe that they are alive.