Lecture #2 - Cell Structure & Function PART 3 (after MT) Flashcards
1
Q
The Endosymbiotic Hypothesis
Mitochondria and chloroplasts evolved from…
A
BACTERIA
2
Q
The Endosymbiotic Hypothesis
Mitochondria and chloroplasts evolved from bacteria
Evidence
A
• SEMI-AUTONOMOUS (organelle can divide & function independent of the rest of the cell!)
- the way bacteria complete binary fission
• CIRCULAR CHROMOSOMES
- Lack histones (Euk property - so fact that these euk organelles have DNA that’s devode/absent of any histone proteins is an indication that it’s likely a prok. origin (or at least not a euk. origin)
• 70S RIBOSOMES - bacterial attribute
- euk’s on their own in their cytoplasm, contain 80S ribosomes
• TWO MEMBRANES (Gram - have 2 membranes also)
• OUTER MEMBRANE HAS PORINS - same as the outer membrane of Gram - bacteria!
- allow opp. for you to bring in hydrophilic like substances non-specifically
3
Q
Where did the specificity come from, when we discussed nutrient uptake, if the porin is non-specific & just provides a pore?
A
ABC transporters & other channels/transporters embedded in the plasma membrane
4
Q
ETC is in the ____ mitochondrial mem., which is like the PM of _____ (where the ETC is located there also)
A
INNER
BACTERIA
- like a prok. PM as the innermost structure
5
Q
The ancestor of chloroplast became…
A
trapped inside a larger cell & now it’s the chloroplast organelle for plants
6
Q
The ancestor of mitochondrion became…
A
trapped inside a cell & now its become the respiring organelle for all of these other cells
7
Q
What does the branchpoint on the phylogenic tree of Bacteria, Euk, & Archaea suggest?
A
that based on genetic analysis shows that Euk & Archaea are gonna have MORE close relationships with one another than they have with bacteria, which constitute its own branch on this phylogenic tree
- interesting b/c you would anticipate that Bact & Archaea (both prok) would be more related to one another & that’s not the case
- but just b/c their both prok. doesn’t mean much - more a structural detail then it is a telling det about any of the characteristics
8
Q
Mitochondria
A
- Most closely related to Rickettsia
- Proteobacteria (phylum Rickettsia fit into)
• Obligate intracellular pathogens
- means they have an obligation to be inside of another cell, & their pathogenetic which means they cause disease specifically RMSF)
• Ex) Rocky-mountain spotted fever
- still bacteria - even though description sounds a lot like they’re viruses (which isn’t true)
- still bacterial organisms, it’s just that they have dev. a tendency/desire to be on the inside of the cell
9
Q
Chloroplasts
A
- Most closely related to Cyanobacteria (*photosynthetic ability)
- Blue-green algae (typically cyanobacteria blooms)
10
Q
What can you tell me about the gram stain. If you were to do a gram stain on Rickettsia & a gram stain on Cyanobacteria & you expected that there was no weirdness or cellular modification, what gram stain would you expect to find?
A
should be pink –> b/c they got 2 diff. mem’s (the outer mem has porins & ETC in inner mem further supporting fact that its a gram - structural organization), have 70S ribosomes & circular chromosome to indicate the fact that their capable of bacterial cellular interior & bacterial function as well
11
Q
What was thought to be the v. 1st life form?
A
Archaea
- able to survive conditions of early Earth –> b/c it was so hot & these organisms are able to handle those excessively high temps & the Euk would evolve after bact. b/t they have organelles
- able to use H2 gas to power their cell (which was v. abundant)
- doesn’t mean ALL archaea evolved 1st, then all bact & all euk –> you just look at organisms that are able to tolerate the temps
12
Q
What colour should the gram stain be of Rickettsia & Cyanobacteria?
A
PINK
13
Q
Viruses
A
- Acellular infectious particles
* Obligate intracellular pathogens
14
Q
What does, “Acellular infectious particles” mean?
A
non-living, goes into a cell & creates a +/- = parasitic relationship (virus benefits & host cell doesn’t), v. small but it’s there
15
Q
What does, “Obligate intracellular pathogens” mean?
A
• Reproduce ONLY INSIDE of living cells
• LACK independent metabolism
–>NOT free-living
has an obligation to be in the boundaries of the cell, in order to actually execute viral replication, within the cell, that it has an obligation to be within the boundaries of the cell, in order to execute viral replication, & is disease causing
16
Q
Are viruses free-living?
A
NO - lack independent metabolism
think: on desk you put sugar, lipids, iron, sodium, water, potassium - anything that’s needed for a living cell to thrive, & then you put virus on top (cough SARS-COV 2 on top of that pile of nutrient for ex), you would NOT get SARS-COV 2 replication (not able to), b/c it doesn’t have the machinery & enzymes for glycolysis & TCA cycle or for fermentation, it doesn’t have ribosomes to protein assembly –> therefore lacking independent metabolism & are therefore NOT free-living
- they’re only able to make more of themselves, if they’re inside of a living cell that provides them with machinery in order to be able to do so
- the virus itself couldn’t infect you, but on the pile on its own don’t expect increase in #
- to contrast, if you put bacteria that were free-living on that pile of nutrients & provided the temp & the pH was within the range for growth, you would def. expect that the # of bacterial cells that fell on that pile of nutrients would now start to increase as a result of growth b/c they do have enzymes for growth, ribosomes for protein syn & can replicate their own nucleic acid, so you can see the diff b/t a virus & a living cell
17
Q
Viruses are composed of at least 2 parts:
A
- Nucleic acid GENOME (DNA or RNA) and protein coat (CAPSID)
- Together=NUCLEOCAPSID (bare min)
(DNA or RNA are the recipes to allow for assembly of viral material)
DNA: hepatitis b, HPV, EBV (casues mono) ALWAYS a DNA virus & will NEVER change
RNA: HIV, Covid, Influenza ALWAYS a RNA virus & will NEVER change
18
Q
Some viruses have an envelope
A
layer of LIPID surrounding the nucleocapsid
19
Q
Naked virus
A
what the collective structure (nucleocapsid) is referred to as
- nucleocapsid - also framework for what we call naked viruses (1 category of viruses)
nucleocapsid - bare min
- proteins - like a protein-shell
- 3-D dome with nucleic acid inside
- nucleic acid - provides recipe for whatever the virus knows it needs to make on its own
- think: if someones coming to your house & they know you don’t have chicken & that’s the only thing they want, that’s the only thing they will bring, pay for & buy b/c everything else they know will be provided - so why waste their space & money on it if they can just use yours & parasitize you
- capsid
- spike proteins - embedded on OUTER surface of the capsid for naked virus - are unique viral characteristics as is the capsid protein
20
Q
Will they find info in YOUR cell to build their capsid protein or to build their spike protein? If not, where is the recipe to make spike protein & capsid protein?
A
NO - it will be on their DNA or RNA
21
Q
Comparison of naked & enveloped virus particles
A
- the envelope originated from host cytoplasmic membrane
Naked:
- Nucleocapsid: nucleic acid & capsid (composed of capsomeres)
Enveloped:
- Nucleocapsid: nucleic acid & capsid
- Envelope
22
Q
Enveloped virus
A
takes time to build an envelope on the outside of the structure & that’s where the spike protein will get embedded or inserted b/c that’s now the outermost layer
23
Q
Imp. things about the viral structure:
- This envelope is acquired from _____ when the virus leaves your cell
A
- This envelope is acquired from YOUR PM when the virus leaves your cell
- so characteristically, what will this envelope be structurally v. similar to?
- it would look exactly like a PM b/c that’s where it came from - BUT it is NOT a PM
- b/c a PM surrounds a living cell creating the boundaries of that cell
- the PM is also gonna provide selective permeability & this envelope does none of that - it’s just an outer layer that it picked up in the process that it uses to leave your cell
- needs it for infectivity b/c that’s where its spike proteins are & spike proteins are critical for infectivity
24
Q
Imp. things about the viral structure:
- Anything that disturbs this envelope, disturbs ____
A
INFECTIVITY
- Covid, HIV, influenza are ENVELOPE VIRUSES
- so any chemical disinfectant that you use that would disrupt a lipid bilayer like a PM will disrupt this envelope, & when it does you lose it, which took the spike protein that were needed for infectivity
25
Which type of virus do you think is more hardy, & which type of virus is more challenging to get rid of when you use chemical disinfectants & things like it?
NAKED VIRUS are HARDER to get rid of - b/c they don't have an envelope to disturb
- LAST LONGER when you use chemical disinfectant & not all disinfectants will work against them
ENVELOPED virus is EASIER to get rid of by comparison
26
Viral Genome
• DNA or RNA- NEVER both
- a virus that's an RNA virus today, is a RNA virus always (doesn't change)
- living cells always have DNA as a component of the cell material
• Single stranded OR double stranded
- we only have ds nucleic acid, but viruses get an option
- HIV, covid, influenza are ssRNA
- HPV is DNA virus
• Circular OR linear (ss or ds)
- if circular & ds - comparable to bacterial chromosome
- if linear & ds - comparable to us
• Can be in several pieces – SEGMENTED
- min. amount of waste virus will have on the cell
* Genome size (complexity varies)
* Smallest ~ 3.6 kb for some ssRNA viruses (3 genes)
* Largest > 150 kbp for some dsDNA viruses (> 100 genes)
27
DNA viruses have the capacity to...
```
cause cancer (some of them)
- b/c their going into the nucleus, interferring with normal cellular activity, they can upset cellular respiration & these processes to make the cell become a danger inside the body
```
28
The type of their _____ can play a role in what that virus' capabilities will be
nucleic acid
29
Non-segmented viral genome
everything in a line
| - b/c it's all together - you need to make 1000 of all
30
The capsid protein (perhaps you need 1000 pieces). What do you know about enzymes & their characteristic that'll determine the quality that you need? Would you need a lot of them?
RECYCLABLE - capacity to be reused multiple times
NEED A LOT
31
What does non-segmented viral genome mean for the cell in terms of its efficiency for viral replication, if you need to make 1000 of a protein that you only need 2 of?
INCREDIABLY wasteful - using our cell to do this
| - more parasitic to the cell if you're being excessively wasteful beyond your need
32
Segmented viral genome
influenza has 8 pieces of RNA that constitutes its genome
- each gene gets its own segment
- so you can make what's needed - NOT being excessively wasteful
BUT you have to package virus into a new viral particle, so it can exit the cell
33
How will a segmented genome might have more problems than a non-segmented genome?
have to take ALL the pieces with you
think: backpack with everything - grab & go (NON-segmented)
wallet, keys, sunglasses, book etc - SEGMENTED --> increase chance you'll leave something behind by mistake & then don't have that to help me for whatever you needed it to do can be detrimental
34
Genome size
* Smallest ~ 3.6 kb for some ssRNA viruses (3 genes)
* Largest > 150 kbp for some dsDNA viruses (> 100 genes)
complexity varies
35
Virion Structure
1 viral particle
36
Virion Structure
Capsid
PROTEIN COAT that SURROUNDS the GENOME
- structure that's part of the nuclear capsid, therefore EVERY SINGLE virus is going to get 1
- compartment where you can pack genetic material into, so you can transfer the viral genome from 1 host cell to another
37
Capsid allows...
transfer of viral genome between host cells (to move it back & forth)
38
Capsid made of...
identical polypeptides – protomers (1 piece you put together)
- cells makes many of these polypeptides (remember ex of 1000 copies of that polypeptides for capsid protein)
RNA is coiling & is able to loop around & form the necessary nucleocapsid unit
39
Helical capsids
polymerizes to create a cylindrical structure
think: how you choose to style your hair & build your house
- capsids have many diff. varieties & "houses" nucleic acids
* Protomers form a spiral cylinder
* Nucleic acid genome coiled inside
* Ex. Tobacco mosaic virus (1st VIRUS ever identified) capsid is made of ~ 2100 identical protomers.
40
What does "~ 2100 identical protomers" mean for the # of enzyme molecules that it's gonna make?
you'll need the same # - need 2100 of everything if its a NON-segmented genome
- if its a segmented genome you can make just what you need
41
Icosahedral capsids
COMMON
* Regular geometric shape with 20 triangular faces
* Exhibit symmetry
* Protomers aggregate to form capsomeres
* Ex. Human papillomaviruses (HPV) have form their capsids from pentamers (clusters of 5)
42
Human papillomaviruses (HPV)
pap smear looks for atypical cells that will be present in a transitional zone
- HPV tends to affect there, transmitted as a sexually transmitted virus, that manipulates the virus to become tumours
- 100% of all cervical cancers are correlated to HPV infection (certain types)
43
Polyhedral Capsid Arrangement
many (doesn't have to be 20)
44
Describe how you form the capsid
protomers are used to form the pentameric capsomere (structure that gets repeated), then the capsomere is polymerized to form the capsid
45
What would you call the pentameric capsomere, where it comes together to form a unit made of multiple polypeptides?
PROTEIN = quaternary structure (specifically)
46
Binal capids
* Geometric HEAD with an attached HELICAL TAIL
* Ex. T4 bacteriophage of E. coli
* GENOME is carried in a POLYHEDRAL head, helical TAIL is used to INJECT DNA into a host cell
*attaching to PROKARYOTIC organisms (not euk)
47
Tail of T4 bacteriophage
serves as a connection to the baseplate where tail fibers attach
48
Binal capids
Ex. T4 bacteriophage of E. coli
lands on surface of a cell, & the genetic material gets inserted into the cell
- rest of viral structure stays outside
think: someone handing something to you through front door (giving stuff you actually need - nucleic acid that will be used for protein syn)
49
Nucleocytoplasmic large DNA viruses
* Viruses with complex MULTI-layered structure
* Ex. Mimivirus (infects amoebae)
• 0.75 μm (prok range) in diameter, 1200 kbp DNA
- LARGER than some bacteria
(size is characteristic of a Euk cell almost (like a small Euk)
50
Envelope
a LIPID BIlayer surrounding the nucleocapsid that was acquired from the host membrane
51
What does the envelope consist of?
* Consists of host lipids and viral proteins – SPIKES
* Ex. Influenza virus
* Flexible helical capsid, surrounded by an envelope
* Two major spikes: hemaglutanin (H) and neuraminidase (N)
52
Two major spikes (on the envelope):
hemaglutanin (H) and neuraminidase (N)
53
Spike proteins are like...
a key that's used to turn a dead bolt
54
If you use a chemical disinfectant that destroys the envelope, the spike protons will...
be gone & the spike proteins lost its key to be able to get into your cell
55
When the host cell (1 of your cells) is infected with virus...
it traffics the spike proteins & then the virus will push out (budding)
- as it pushes out & takes with it a new envelope
56
Since the envelope was a portion of the PM of your cell, what else is gonna be present in this envelope?
spike proteins & your OWN protein b/c its your cell that it's taking this from
- could be a glucose transporter for ex
57
How can this pose a challenge for your body, if the virus that's replicating inside of you that's enveloped, has your proteins & his own proteins within the structure?
immune system is confused b/c spike proteins don't belong but realize that's its glut transporter so it shouldn't kill itself
- so it's confused that almost serves as an immune evasion to allow this organism to create that confusion
58
The virus goes into 1 of your cells, using an attachment to the deadbolt (surface receptor, sialic acid). But when the virus leaves, it...
buds out
- when its leaving, what is the cell that's its leaving from gonna have on its surface if you consider how it got in
- cell will have sialic acid - same way that it used sialic acid on the PM to bind & get in, its now gonna wanna stick to the same cell its already affected with b/c of the attraction b/t hemaglutanin & sialic acid
think: wearing suit with velcro in house
- outside of house is covered in velcro, so you stick to walls of same house you've already been inside
- but want to go 5 houses down, so you pack a velcro peeler to separate self from house so you can move down street & attach to velcro on another house
analogy: virus using N to peel itself off of sialic acid located on surface of cell that's already affected so it can freely move to another cell nearby where it sticks with hemaglutanin to that sialic acid so its able to cause a + infection in that location
59
Imp. feature of the virus that antiviral features make use of is...
N target
- ability to inhibit this enzyme, which makes people who have influenza less sick & virus will be less successful b/c it'll get into fewer houses
- if it doesn't get into as many of your cells, you're not gonna have as dramatic of an infection (viral load lower, therefore symptoms will be controlled)
60
Hemaglutanin (H) spikes
key used to turn the deadbolt
- attaches to what we have on our respiratory cells, referred to as SIALIC ACID (deadbolt that key inserts to )
- once that insertion has taken place, the virus is able to go into the cell & create an infection
61
From the nomenclature, what are N spikes gonna be?
enzyme - lots of types
62
H1N1, H4N3, H5N1, H2N7 are
antigenic VARIANTS of influenza BASED on TYPE OF HEMAGGLUTANIN (H1 --> type 1)
- still similar enough to be hemaglutanin but diff b/t them is slight variation that makes previous immunity, previous responses to it, less effective
think: moving to diff place with diff culture, if you come back you will have picked up certain attributes from your surroundings, but still same person (subtle changes)
- dying hair little darker or little lighter brown
- still brunette, but slight change occurred
63
Viruses infect...
ALL domains of life
| - but NEED key to make it possible (attachment)
64
Bacteriophage (phage)
viruses that infect bacteria
• Ex) T4 Phage – infects E. coli
bacterium has ribosomes & materials to support viral replication, but a bacterium is also small
65
Animal viruses
infect and multiply only inside of animal cells
• Ex) Human papillomavirus (HPV) – infects human epithelial cells (provide lining of your body)
• Causes benign tumors (warts)
66
Describe benign tumours (warts)
- get virus b/c you stepped on a place where someone was shedding the virus
- virus moves down tiny tears on SKIN SURFACE
- infects on STRATUM BASALE (MITOTICALLY ACTIVE CELL)
- outcome of having created that infection: cell is able to reproduce the virus for him but also the virus produce proteins to collectively upset the mitotic cycle (proteins makes cell to not be in control anymore & to mitos like crazy, so cell becomes a beigin tumour or cervical cancer is not beigin)
- as it becomes a tumour (excessive replication which is only for the virus to fulfill its own desire), all the cell layers get pushed up & get a wart & virus will start being shed so when you step somewhere you will give it to somebody (v. contagious)
67
How do you treat a benign tumour (wart)?
if there are black roots, you have to use an acid (salicylic acid) to kill all the epidermal layers to expose this & then chemical kills it & that's the reservoir of virus so wart will heal & go away
68
What does animal viruses play role in?
plays role in terms of specificity (in lab can't take an HIV virus & give it to a guinea pig b/c they don't become affected with HIV b/c appro. receptor & conditions aren't there)
69
Describe jumping the species barrier
can have mutation (like covid)
- when people who are in close proximity with animals (ex, working with livestock or live animals market), animals have all kinds of viruses unique to them & then as those viruses mutate just like covid it can develop the ability to use a diff lock, mutate & infect a diff type of cell
- -> called jumping the species barrier (all of a sudden that virus can infect things it never did before)
70
Most viruses are specific to a ____ host species
SINGLE (ex: animal virus)
71
Virus must attach to _______ on the host cell surface
SPECIFIC RECEPTORS
• Ex) HIV binds to CD4
• (CD4 is a) Chemoreceptor (immune function) on surface of some human immune system cells
• HIV infects only humans
72
Some viruses infect...
more than 1 species
• Ex) Influenza attaches to a glycoprotein found on surface of several animal cells
- H/N have so many diff versions - not feasible everyone can be vaccinated against every single one
- glycoprotein: sialic acid is the sugar that's imbedded in the lipid portion of mem
• Infects humans, pigs, chickens, seals etc.
73
SARS COV-2 uses...
ACE-2
- causes BP to go up - causes vasoconstriction b/c of low BP as your stimulus
- now ACE-2 naturally is used to get rid of angiotension II - involved in BP regulation & the virus has evolved to use that & bust into our cells
SPECIFIC INTERACTION HAS A SPECIFIC KEY
74
Why can't we ever be able to eradicate infection?
1. b/c can't vaccinate all livestock & other animals that cause infection within themselves & animals have fast turn over (slaughter)
2. so many diff types - H1N2 etc., all require vaccination
stuck with influenza forever but hope it doesn't cause bad pandemics - causing wide spread death
75
delta32 mutation in northern Europe
deletion mutation of 32 nucleotides for CCR5
76
If you're missing 32 nucleotides for this protein in its receptor, what must that mean for the recipe & the result you'll get when you translate it?
deletion
- taken out a bunch of nucleoties, therefore there's no way the protein will be the same/folded the same
- people with this mutation are resistant to CCR5 form of HIV b/c their co-receptors are inefficient
77
Influenza Your cell
Influenza Your cell
```
Hemaglutin. sialic acid
HIV
gp120 CD4
SARS COV-2 spike protein ACE-2
keys deadbolts
```
78
Viral Replication Cycle
1. Adsorption – attachment to the host cell
2. Penetration and uncoating – entry into the host cell
3. Synthesis of viral nucleic acids and protein
4. Assembly of new virions
79
Viral Replication Cycle
1. Adsorption
– attachment to the host cell (STICKING KEY IN THE LOCK)
• Involves specific receptors on the host cell surface
• Ex) LPS, outer membrane proteins or glycoproteins (type of receptor - protein in mem. that has sugar moites added to it in order to allow the virus to get in)
80
What does it mean that during Adsorption, it "Involves specific receptors on the host cell surface"?
NONE of these receptors were built & installed into your mem., in order to actually make your cell infectable (instead, we use these receptors for immune cell function, BP reg, etc. BUT the virus has EVOLVED to use them)
81
Describe zoonotic viruses
why livestock markets for ex, increase chance of being in contact with viral sources that are from animals --> called ZOONOTIC VIRUSES & if those viruses dev. a mutation that suddenly allow them to stick their key into 1 of the locks on your cell then your infectable by that virus --> doesn't take much for them to JUMP THE SPECIES BARRIER if given the opp. & then you have a new human virus (either beign (flu symptom) or serious)
82
If its a virus that's attaching to LPS (outer mem. proteins) as the key to get in - what kind of cell is it infecting?
gram - bacterium; virus that infects them are called = BACTERIOPHAGE
83
Viral Replication Cycle
2. Penetration and uncoating
– entry into the host cell
• Bacteriophage – usually inject their nucleic acid into the cell
- to conserve space & increase efficiency
- nucleic acid is all info needed to build new virus
• Leave the capsid outside the cell as a “ghost”
- leaving behind a lot of its junk b/c proks are SMALL
think: when entering house you take shoes off & put bag down, so only you come in
84
Naked virus = _____
ENDOCYTOSIS
| their only option
85
Enveloped virus = ______
FUSION OR ENDOCYTOSIS
| fuses its envelope containing its spike proteins with the PM of the host cell
86
What happens once nucleic acid gets inside for naked & envelope virus?
- if it got in with endocyotosis - it needs to disrupt the endosome
- if it got in with the fusion - it just needs to open the capsid
purpose: letting its nucleic acid OUT b/c its the recipe to make more virus
87
Entry by animal viruses
• FUSION with the plasma membrane
• ENDOCYTOSIS (form endosome)
- Binding to specific receptors triggers normal endocytic activity
• In EITHER case, once inside:
- The capsid is removed
- Viral genome is released into the cell
virus has opp. to be able to USE nucleic acid
88
Viral Replication Cycle
3. Synthesis of viral nucleic acids and protein
Once inside it:
• Viral genes are expressed and viral proteins are synthesized (by the host’s own ribosomes)
• Viral genome is replicated (by the host’s replication machinery)
89
Viral Replication Cycle
3. Synthesis of viral nucleic acids and protein
Is essentially,
an intense period of metabolic activity to be able to build the material needed to produce new viruses (spike proteins, capsomeres, replicated nucleic acid (DNA virus: IN NUCLEUS, RNA virus: IN CYTOPLASM)
- happens with host cell ribosomes, host cell enzymes, UNLESS we don't have the enzyme then they bring it along to allow for purposes of replication to occur
90
Where do we have all our DNA & replication tools for it?
the nucleus
91
Do we have any tools inside our cell, that allows use to take RNA & make more RNA?
NO - RNA viruses replicate in cytoplasm b/c they bring OWN TOOLS for purpose of replication - do it themselves
92
Viral Replication Cycle
4. Assembly of new virions
* Viral proteins are assembled into capsids, and then genomes are packaged into nucleocapsids
* Viruses do not reproduce by division
think: got all wood, windows, nails for 10 houses & now have to put it together to build a house
93
Cytoplasmic assembly of NAKED virus
spikes get put on in cytoplasm
94
Enveloped virus assembly
spikes put in PM
- need to get envelope in release process
- needs to get out
think: pulling on stick of dynamite & it goes poof
- spikes put in PM
- budding off of infected cell
95
Viral Replication Cycle
5. Release of new virions
Two basic strategies:
i. NAKED viruses usually accumulate, eventually lysing the host cell to release progeny – LYTIC INFECTION
ii. ENVELOPED viruses are usually released by BUDDING
• Virions push through the cytoplasmic membrane without killing the host cell – PERSISTANT INFECTION
96
Can you live for a LONG time with a naked viral infection? Why or why not?
No - b/c it blows up your cell & so if thats happening again & again, you won't get a persistent infection b/c its killing your cells so aggressively to sustain its own replication
97
Can you live for a LONG time with a enveloped viral infection? Why or why not?
For enveloped virus (ex: HIV etc.), you can live for a long time with it. Creates a persistent infection, & its not killing the cell when its leaving but rather just closes the gate behind it & restores the structure of the PM
- eventually, cell gets tired of replicating virus & even though the virus doesn't kill it, the cell will give up & have a programmed cell death
- takes longer to reach death but it happens
(HIV --> AIDS (excellerated death of their virally infected T helper cells - at that point don't have a lot of immune function left b/c your losing your cells dramatically)
98
Budding
– release of enveloped viruses
• Viral proteins inserted into the HOST MEMBRANE – SPIKES
- NUCLEOCAPSID associates with the spikes, and buds through the membrane to FORM the ENVELOPE
99
Budding ex)
Ex) Influenza
• Neuraminidase Allows new virions to EXIT the host cell
- used to PEEL - b/c as virus is leaving it uses N to not allow it to stick, so the virus has to leave
- benefit for the virus: goes on & infects diff cell so virus can be more reproductively successful by having more target inside the cell
• Hemagglutanin Allows viruses to ADSORB to the next host
100
Which Neuraminidase(s) inhibitors do we use?
Tamiflu/relenza
| - inhibit neuramindase activity (so it can't peel)
101
Does tamiflu/relenza (which inhibit neuramindase activity) clear the infection (cure)?
NO - it keeps it contained; minimizes # of cells in your respiratory tract that actively became infected b/c less virus is free to go in & bust other cells when on these inhibitors, therefore lessens severity of disease
102
How will Tamiflu/relenza (inhibit neuramindase activity) be beneficial to others, if you take this drug when experiencing bad version of flu?
you're infected, but if you don't have as much in you b/c you're limiting the amount of replication (b/c these drugs prevent virus from escaping to other cells, lowering the reservoir - meaning theres less in you to spread which therefore means you will be less of a danger to others)
