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78 Cards in this Set

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  • Back
Name the components that make up a virus
capsid, nucleic acid, & envelop (if applicable)
List the 3 ways a virus can attach to a cell
Direct Injection
Explain endocytosis as a way to attach
Chemically fit together, The cell will engulf the whole virus. The membrane and capsid will be degrated in cytoplasm.
Envelop or Non-envelop
removal of capsid within a host cell
Explain fusion as a way of attachment
The 2 membranes must match together via protein spikes. The phospholipid membrane of host cell will fuse with the envelop of virus and the capsid will be released inside cell. Protein spikes will be left of membrane.
ONLY envelop cells
Explain direct injection
The capsid will interact with the membrane of the cell and attach. It will inject genome into cell
ONLY Non-envelop
Why is it so important for a virus to get inside our cell
Use our DNA to replicate its own
How many genes are produced when a virus replicates?
Varies but only few because only composed of a few genes
cleaves host's cell DNA at certain points to allow small portion of viral DNA to be made.
Why does Integrase pose a problem to our cells functions?
May disrupt vital functions

ex. mitosis/meiosis has waiting period and if disrupted, cause cancer
Retro virus
+ssRNA that uses Reverse Transcriptase to allow the genome to be replicated in cytoplasm.
What is used to produce DNA from RNA
Reverse Transcriptase
Give the order in which Reverse Transcriptase converts RNA to DNA
RNA/DNA hybrid-->RNA degrated-->DNA produces double strand
What are some downfalls to Reverse Transcriptase?
When turning it into DNA, it makes many mistakes. There will be mutations in viral nucleic acid (Frameshift mutation)
What kind of mutation does Reverse Transcriptase cause?
Frameshift mutation
Why can't we produce a vaccine for a retro virus?
With all the mistakes that the Rev. Trans. makes, the proteins are always changing
Explain the parts viruses need to replicate and who provides each
Virus provides promotor, operator, terminating sequence
Host cell provides RNA polymerase.

There will be a promotor and operator and the host cell will go through the process. The virus will have a specific RBS for its genes while the host's cell will have another.
Can there be mutations to the host cell?
Yes, if the virus inserts its gene right in the middle of host's gene, the host's gene will not be transcripted correctly=Frame shift Mutation
Where do DNA viruses assemble?
Genome in nucleus and rest in cytoplasm
Where do RNA viruses assemble?
How can cells release viruses?
Cell Bursts
Budding Off
Explain Budding off
After the cell has assembled in the cytoplasm, it will migrate to outer membrane. It will interact with membrane and push through->exocytosis. Part of the membrane will be the envelop around the capsid. This membrane will contain spike proteins.
What kind of viruses can bud off?
Envelop viruses
Explain how the cell bursts when releasing viruses.
The viruses in the cell are building up and the cell eventually bursts (lyses), releasing the new viruses
Explain lysogenic
The ability of a bacteriophage to insert it's DNA into the cell but it doesn't produce more viruses. Instead it's genome is copied through the generations as the cell multiplies.
What is the advantage of lysogentic?
Survival-it allows the host to reproduce so there are more places for the new viruses to invade.
Explain lytic
Process of making new viruses
-can bud or burst
What are some characteristics of a bacteriophage?
-can attack both +/- cells
-doesn't contain an envelop
-has additional proteins
-specific association/interaction with tail fibers
Why would a bacteriophage be able to bud off in 1 cell but a virus be unable to infect that same cell.
The cell wall of the host cell has a cell wall that prevents budding off
enzyme that bacteriophages carry that breaks down the peptidoglycan
How is genome transfered in bacteriophages?
The high pressure in the head allows for the sheath to insert hollow rod into cell through membrane/cell wall
What happens to genome once it's inserted into cell via a bacteriophage?
1. Used directly-lytis
2. Incorporated into genome-lysogenic
How are bacteriophages released?
The lysozyme helps break the peptidoglycan of cell wall and cell will lyse, releasing bacteriophages
+ssRNA virus
envelop virus
effects T-cells
Describe the specific parts of a HIV virus
Capsid-holds 3 enzymes
-Reverse Transcriptase
Few strands of RNA
What are the genes associated with HIV and what do each do?
gag-produces produces capsid
env-produces the envelop
pol-produce RNA poly/Reverse Transcriptase
What does HIV contain that allows it to attach with T-cells?
What does a T-cell do?
It picks up foreign particles that a cell has attached to a protein. They interact and the T-Cell releases a horomone (cytocyme) and triggers B-cells to produce antibodies
What do B-cells do?
They are triggered by the release of cytocyme by T-cells and they produce antibodies
horomone release by T-cell that triggers B-cell
What do antibodies do?
They attach to other foreign particles that haven't been engulfed by macrophages. There is an open end for natural killer cells to attach.
What do natural killer cells do?
The natural killer cells will release toxins to kill foreign particle
What do T-cells contain that HIV attaches to.
The CD4 protein on the surface of the T-cell is highly attracted to the gp41 and gp120 on the virus
How does HIV get into our cells?
gp41, gp120, & CD4 interact and bring capsid into cell. The capsid is broken down and the +RNA strands are released.
What doesn't Reverse Transcriptase need to start that other viruses need?
How does the replication of HIV start?
The ribosome binding site is already there with start codon and in the right order.
If HIV contains RNA, how can it replicate its genome?
Reverse Transcriptase
How is the newly made DNA put into host's cell?
After genome is in place, what will HIV do?
1. Divide-lysogenic
2. GO on to make capsids, gp120,...and leave cell via budding
How does HIV harm the T-cell?
It will bud off so much that it will kill the cell.
How are HIV's enzymes utilized?
1. Integrase-puts HIV DNA into cell's
2. Protease- cleaves proteins and makes virus active
3. Reverse Transcriptase-turns RNA to DNA
How does HIV harm the organism?
Without T-cells, antibodies can't be made and can't prevent other foreign particles from harming cells
trigger our body to produce antibodies and prevent infection
How are most vaccines created?
Inject radiated Particles. The DNA has been mutated so much that it won't function as a virus but our cells don't know that. They produce antibodies that create memory cells for that particle.
Why can't there be a vaccine for HIV?
HIV attaches to proteins that are always changing so it will be like the first time exposed each time it changes.
What is the main difference between HIV and other infections?
Where it sticks--always changing
extremely small pieces of RNA that lack capsid
"self-replicating" proteins that contain no nucleic acid
alpha helix; normal and carries out protein functions
Beta Sheets; degenerative and breaks down similar tissues; will interact with prp, cleave it, and make it turn to prp*
How can something without nucleic acid replicate?
List 2 examples of prions
1. Transmissible Spongeform Encephalopathics (TSE)
2. Bovine Spongeform Encephalopathics (BSE) AKA Mad Cow Disease.
Why can't we find a cure for BSE or TSE?
prp is extremely heat stable. They have tried to use radiation. Radiation causes mutations in DNA. But we aren't talking about a bacteria, it's a protein and you CANNOT change it's DNA.
What are the chances of getting TSE?
Everyone has prp in them but it is only a risk if methiomine is on the 129th amino acid. 40% of people do.
How come staphylococcus can live on human skin.
It can tolerate the high NaCl and lack of water.

**It uses NaCl in an antiport system: brings in NaCl and pumps out H+
How does our skin a defense against bacteria?
-Elastic-lots of cell to cell interaction
-Continuously sloughing and cleansing
-Dry and salty and most can't tolerate this environment
Where is lysozyme found?
Eyes and pores
How does the mucosal lining protect against foreign particles?
The M cells will take in the bacteria and hand it off to a macrophage. It will put it on its surface with a protein. T-cell will interact and produce cytocyne whick triggers B-Cells. The B-Cells release sIgA which is pumped back to mucosal lining.??
How does a macrophage degrade bacteria?
It takes it in and interacts with a vacuole containing protease, lysozyme, and oxygen free radicals. This environment isn't good.
What does each enzyme that a macrophage has do to the bacteria?
lysozyme-breaks down membrane
protease-degrades protein
oxygen free radicals-
Where does the protease come from?
Any protein made in ER usually folds with golgi apparatus. A piece of golgi will bud off and there are new proteins. Protease degrades proteins
If bacteria were to get into the bloodstream, what would be available for the line of defense?
Few macrophages start the process and produce antibodies. These antibodies will hook up with natural killer cells and they will take care of the 1,000's more.
Dendritic Cells
Part of our line of defense in the skin. They have long appendages with lots of surface area. Work like macrophages
Why do cuts become inflamed?
Before any other defense system can come, inflamation will occur due to neutrophils pushing into area
short life defense system that flood area and cause it to rise. They stay here until they die and turn to pus
Compliment System
-C1 associates with antibodies and changes shape
-C5 associates with membrane-6-7-8-9
-C9 can span through phospholipid bilayer and form hole
MAC system
Why is a hole in the bacteria so bad
It loses its proton motive force and is unable to bring in sugars and nutrients. Toxins are able to come in and cell will lyse