1
Q
Bacteria can be seen under a
A
Light microscope
2
Q
Viruses can be seen under an
A
Electron microscope
3
Q
Non-reproducing, non-metabolizing “particles”
A
Have a genome, but no enzymes to copy their genome
- Don’t code for enzymes to make ATP from nutrients
- Don’t take in food, don’t take in waste
- Not “living”, considered “infectious particles”
4
Q
Virus that’s not in a host cell, floating free waiting to find the right host cell
- Not reproducing/ metabolizing
A
Virion
5
Q
Obligate intracellular parasites
A
Their genome changes the behavior of that host cell and forces it to make copies of the virus particles
- Only functions inside host cells
6
Q
3 virus designs
A
Naked, Enveloped, Bacteriophages
7
Q
Naked viruses
A
Eukaryotic host cells
Basic (unenveloped)
Consist of strand(s) of genetic material making up the genome and a hard protein shell (only nucleocapsid)
8
Q
Enveloped viruses
A
Eukaryotic host cells
Luxury model
Have the naked virus components (nucleocapsid) with an envelope wrapped around the hard protein shell
9
Q
Bacteriophages
A
Prokaryotic host cells
Phages
Viruses that infect bacteria
Name not accurate bc they don’t eat bacteria, only looked like they did on Petri dishes when they were first discovered
10
Q
Different kinds of genomes viruses can have
A
ssRNA (+ or - sense)
dsRNA
ssDNA
dsDNA
11
Q
Protein capsid (shell)
A
Composed of capsomere proteins (or nucleoproteins if packed close around nucleic acid)
Capsomeres often organized into icosahedron (10-20 sides, most common shape when capsomeres not connected to genetic material)
12
Q
Enveloped virus ligands
A
Peplomers
13
Q
Naked virus ligands
A
Capsomeres
14
Q
Bacteriophage virus ligands
A
Binding proteins on bottom of tail fibers (capsomeres)
15
Q
Which kind of virus is vulnerable to drying or chemicals outside body?
A
Enveloped viruses
16
Q
Where do enveloped viruses get their envelope (outer phospholipid bilayer membrane) from?
A
Taken from last host
17
Q
Which kind of virus could “hide” from your immune system?
A
Enveloped viruses (outer membrane made from our membranes)
18
Q
Which kind of cell could be detrimental outside of the human body?
A
Enveloped viruses
19
Q
What kind of viruses are vulnerable to the immune system but when outside of the body is much more sturdy?
Can persist in water, food, tabletops, doorknobs
A
Naked viruses (hard rigid shell)
20
Q
Can you contract an enveloped virus without having close proximity and contact (sex, shared blood/ body fluid, respiratory droplets)?
A
No
21
Q
If you could only transmit a virus by pus from lesions, what kind of virus is it?
A
Enveloped viruses
22
Q
What kind of virus is limited in how it can be spread?
A
Enveloped viruses
23
Q
Are naked viruses more pathogenic than enveloped viruses?
A
No, the difference is where they’re vulnerable
24
Q
What kind of virus would use stability proteins?
A
Enveloped viruses
25
What is the function of stability proteins?
Extends the viability of an enveloped virus
26
Do stability proteins make enveloped viruses as sturdy/ stable as naked viruses?
No
27
Can naked viruses last basically forever, floating around in a harsh environment?
Yes
28
Reverse transcriptase
Make DNA from RNA
- Backwards from the central dogma
- Brings in genome of ssRNA & it uses that RNA to construct complementary DNA
29
RNA-dependent RNA polymerase
Uses RNA template to construct new complementary RNA
- Viruses that have an RNA genome that must make new RNA from their genome have to bring this enzyme in
30
Protease
Cuts viral multi-proteins
- If a virus uses this enzyme, it's known as a fast virus
31
Integrase
Connects viral genes to host genome (incorporation) to make provirus
- It will live as part of the genetic makeup of that host cell for the rest of that host cell's life, including being copied when the cell reproduces to be passed on to the daughter cells
32
What's left of the virus after incorporation?
The viral DNA
33
Provirus
Viral DNA hiding as a part of host genome (not expressed)
34
Can we cure diseases in which the virus uses integrase? Why or why not?
No bc until we can come up with an enzyme that can go into every cell and cut out the incorporated viral DNA, we can't cure it
35
Viral construction of bacteriophages
Capsid head (nucleocapsid), tail, tail fibers on baseplate, lysozyme on baseplate spikes
36
Do viruses have the ability to replicate themselves/ reproduce?
No
36
Lysozyme
Digests peptidoglycan in cell wall
(Bacteriophages only bc they're the only viruses that have to push through a peptidoglycan layer)
37
Lytic life cycle
(Virulent (extreme) viruses)
A virus that enters the host cell and immediately expresses its genes to coerce that host cell to make new virus particles
38
Are lytic cycle viruses more likely to kill you? Why or why not?
No bc just bc a virus enters and its genetic material may not be expressed until later doesn't have anything to do with how dangerous it is
39
Lytic life cycle steps
1. Attachment (adhesion)
2. Entry (penetration)
3. Bacterial chromosome degraded (bacteriophages only)
3. Synthesis
4. Assembly
6. Release
40
1. Attachment (adhesion)
The viral particle bumps into a host cell, and its folded proteins are a perfect match for the right host cell, and it sticks to the outside surface of that host cell
41
2. Entry (penetration)
When the genetic material of the virus is going to be released into the cytoplasm of the host cell, variety of ways that this needs to happen (step with most different options)
42
3. Bacterial chromosome degraded (Bacteriophages only)
Once the viral genes are in the cytoplasm, they will take over the activity of the host cell, that will then be the only instructions the host cell is following, it will not be following its own genetic material instructions
43
3. Synthesis
When the host cell is busy synthesizing/ making viral parts
44
4. Assembly
All the different viral parts (capsomeres, enzymes, peplomers, matrix proteins, genome) are put together into that viral particle
45
5. Release
The newly assembled viral particles are released from the host cell and each new nori’s particle goes out to infect another host cell
(Not always through a lysis event)
46
Can your antibodies also affect the penetration stage of the viral life cycle?
Yes
47
Can naked viruses use any of their capsomeres as ligands?
Yes
48
What kind of proteins does SARS CoV-2 attach to?
ACE2 receptor proteins
- Macrophages
- Epithelial cells
- Microglia
- Neuron cells
49
If someone had long COVID or brain fog, what type of cells did SARS CoV-2 affect?
Neuron cells
50
True or false
If you have a drug that attacks the entry, it’s typically going to attack the adhesion rather than the penetration step
TRUE
51
Bacteriophage penetration
“Squat & squirt”
The tail goes through the outer layers of the bacterial cell until it reaches the peptidoglycan, you’re gonna have digestion of a little hole with lysozyme. The tail contracts and pushes the genetic material through to the enzyme. The capsid stays to plug the hole.
52
True or false
With bacteriophages, the genetic material is the only part of the virus that goes in the host’s cytoplasm
TRUE
53
True or false
Lysozyme is kept on the tail fibers of the bacteriophage
FALSE, baseplate
54
Different ways naked viruses can penetrate the host cell
Endocytosis
Direct entry
55
Endocytosis (penetration)
The cell is going to voluntarily engulf the virus bc it sensed a protein-rich particle on the surface. It places the virus (nucleocapsid) in a vesicle. This is followed by uncoating (the process of stripping away the coat (capsid) to expose the genetic material, often uses part of the digestive enzymes inside the little pouch so as the cell starts to digest the little particles, it digests away the capsid and then the genetic material escapes into the cytoplasm)
56
Antiviral drugs for endocytosis (penetration)
Uncoating inhibitors
57
You’ve just discovered a new virus, it appears to be susceptible to uncoating inhibitors, which stage of the viral life cycle is being affected?
Penetration by endocytosis
58
Direct entry (penetration)
Ligands (which are attached to receptor proteins on the surface of the host cell) pivot/ swivel to create pore. Genetic material can just dribble out into the host cell. Only the genome enters so no need for uncoating
59
You have a virus that seems to be unaffected by uncoating inhibitors, how does it enter the host cell?
Direct entry
60
Fusion (penetration)
During attachment when the phospholipid bilayer of the host cell and the phospholipid bilayer that is the envelope of the virus are attached to one another, so they can fuse/ merge to become one solid phospholipid bilayer. The peplomers stay on the outer surface of the host cell. Still going to have uncoating bc the nucleocapsid is whole in the host cell
61
Different ways naked viruses can penetrate the host cell
Endocytosis
Direct entry
Fusion
62
Antiviral drugs for fusion (penetration)
Fusion inhibitors
63
True or false
If an enveloped virus entered a host cell through fusion and the peplomers are now on the outside of that host cell, that’s one of the ways your immune system recognizes abnormalities to kill that cell
TRUE
64
Synthesis
Host genome shuts down, genome of the virus directs all cell resources towards viral progeny (offspring). You have to use different enzymes and do slightly different steps depending on which genetic material you brought in. Produces genome copies and viral proteins
65
What’s the protein all viruses HAVE to make?
Capsomeres
66
Where do the proteins go that are made through synthesis?
In the nucleocapsid of the new virus (exception peplomers and lysozyme)
67
Start codon for virus RNA to do able to make proteins
AUG
68
Start codon of positive sense RNA
AUG
69
Start codon of negative sense RNA
UAC
70
True or false
Regardless of what genome you bring in, you have to make positive sense RNA
TRUE
71
Antiviral drugs that attack synthesis
Nucleoside inhibitors/ base analogues
RNA dependent RNA polymerase blockers
72
Nucleoside inhibitors/ base analogues
Blocks synthesis by using “fake” nucleotide drug replaces normal nucleotides in DNA
73
Why do nucleoside inhibitors/ base analogues work for virus DNA but not ours?
We make DNA relatively slowly, with lots of spell checkers. While viral DNA construction is typically fast, sloppy, and has no spell checkers
74
RNA dependent RNA polymerase blockers
Blocks synthesis by blocking the enzyme that’s used to make RNA from RNA
75
You’ve just discovered a new drug that appears to block the production of RNA from RNA, what’s the antiviral drug and what kind of genome does the virus have?
RNA dependent RNA transcriptase blockers
RNA genome
76
Where do peplomers go after synthesis?
Any membrane in the cell, the cell membrane, nuclear membrane, golgi apparatus, endoplasmic reticulum
77
Capsomeres join to form
Capsid
78
Fast viruses must use the enzyme
Protease
79
Drug X, which you've just discovered, appears to block the assembly stage of the virus's life cycle by preventing proteins from being made. What kind of drug is it?
Protease inhibitor, fast virus, fast life cycle
80
What step do protease inhibitors block?
Assembly
81
How do bacteriophages release from host cell?
Host cell explodes, the lysozyme eats a hole in the peptidoglycan, cell wall is now damaged, water enters, bursting the cell
82
Different ways naked viruses release
Host cell lyses
Secreted (exocytosis)
83
Host cell lyses (release)
The virus changes the selective nature of the membrane, the cell takes on a bunch of water and overexpands (mimics bacteriophage, just doesn't need lysozyme)
84
Secreted (exocytosis) (release)
Virus put in a small vesicle and the vesicle travels toward the cell's surface and it's going to merge with the cell membrane and it extrudes the contents
85
How do enveloped viruses release?
Budding
85
True or false
If viruses are secreted out of the cell, that means the host cell isn't going to die
FALSE, a cell that's involved in the lytic cycle is doomed to die, the host cell genome is shut down
86
Budding (release)
Viruses must bud out to gain envelope and peplomers, if the peplomers attach to an inner membrane, it buds out through the inner membrane and is still in host cell so it would then have to leave through exocytosis
87
Release is also called what?
Lysis bc that's the most common method of release, but we call it release bc not every virus exits by lysis
88
True or false
If a drug prevents budding, that cell is saved
FALSE, the cell is already infected, doomed to die
89
Lysogenic life cycle
(Temperate (mild) viruses)
A virus that enters the host cell but there may be a bit of delay time before the viral genes may coerse the host cell to start making viral particles
90
Lysogenic life cycle steps
1. Attachment
2. Penetration
3. Incorporation
4. Synthesis
5. Assembly
6. Release
91
How many of the steps in lytic and lysogenic life cycles are the same? What are they?
4
Attachment, penetration, assembly, release
92
What's different about lysogenic synthesis compared to lytic synthesis?
It uses the proviral DNA, no matter what the original genome type virus was
93
3. Incorporation
Viral genes join host cell genome (integrase needed). Incorporated viral genes called provirus, it's gonna sit quietly for a while until it get's triggered
94
Antiviral drug for incorporation
Integrase inhibitors
(If they can't incorporate, they can't carry out heir life cycle)
95
Known triggers of proviral DNA
Chemical, physical, or emotional trauma, age, hormones, other illnesses, UV radiation, ratio of AA arginine to AA lysine
96
Why is age a trigger for proviruses?
The older you get, the less able your immune system is to suppress the activation
97
Why is shingles mainly in old people?
That chickenpox viral DNA has been sitting in their nerve cells since they were a kid, then you're gonna get shingles whenever it gets triggered, the older you are, the more likely you are
98
What kind of hormones can trigger proviruses?
Certain hormones in the menstrual cycle
99
What kind of illnesses can trigger proviruses?
Cold or fever (fighting off an infection)
100
True or false
If the AA arginine is in higher proportion than the AA lysine in your diet, you are much more likely to have a triggering of your proviral genes
TRUE
101
Examples of AA arginine and AA lysine
AA arginine: nut or bean derived foods
AA lysine: breads and especially in dairy products
102
First step of lysogenic synthesis
Unzip the DNA (take away the hydrogen bonds), the 2 strands of DNA are still attached to the host cell DNA but they are free (not attached to partner)
103
Animal virus types of lysogenic life cycles
Latent
Persistent
Tumor formation
104
Latent lysogenic life cycle
No viral particles released in between (somebody can have the infection and not be releasing any virus particles and have no symptoms that they're infected by a virus bc the viral genes are in there, but there's no cell being taken over)
105
Persistent lysogenic life cycle
Continuous release, cell lives
Occurs when the provirus is formed and it immediately and continuously releases a few viral particles all the time without killing the cell and without stopping the cell from performing its activity (super sneaky bc people will not have a sign that the virus is replicating, but they will still be infectious to others)
106
True or false
Genital and oral herpes combine latent and persistent lysogenic infections
TRUE
107
BIO 280
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