Lecture #2 - Cell Structure & Function PART 3 (after MT) Flashcards

Question

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?

Answer 1

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

Answer 2

• 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)

Answer 3

``` 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 ```

Answer 4

nucleic acid

Answer 5

everything in a line | - b/c it's all together - you need to make 1000 of all

Answer 6

RECYCLABLE - capacity to be reused multiple times NEED A LOT

Answer 7

INCREDIABLY wasteful - using our cell to do this | - more parasitic to the cell if you're being excessively wasteful beyond your need

Answer 8

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

Answer 9

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

Answer 10

* Smallest ~ 3.6 kb for some ssRNA viruses (3 genes) * Largest > 150 kbp for some dsDNA viruses (> 100 genes) complexity varies

Answer 11

1 viral particle

Answer 12

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

Answer 13

transfer of viral genome between host cells (to move it back & forth)

Answer 14

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

Answer 15

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.

Answer 16

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

Answer 17

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)

Answer 18

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)

Answer 19

many (doesn't have to be 20)

Answer 20

protomers are used to form the pentameric capsomere (structure that gets repeated), then the capsomere is polymerized to form the capsid

Answer 21

PROTEIN = quaternary structure (specifically)

Answer 22

* 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)

Answer 23

serves as a connection to the baseplate where tail fibers attach

Answer 24

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)

Answer 25

* 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)

Answer 26

a LIPID BIlayer surrounding the nucleocapsid that was acquired from the host membrane

Answer 27

* 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)

Answer 28

hemaglutanin (H) and neuraminidase (N)

Answer 29

a key that's used to turn a dead bolt

Answer 30

be gone & the spike proteins lost its key to be able to get into your cell

Answer 31

it traffics the spike proteins & then the virus will push out (budding) - as it pushes out & takes with it a new envelope

Answer 32

spike proteins & your OWN protein b/c its your cell that it's taking this from - could be a glucose transporter for ex

Answer 33

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

Answer 34

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

Answer 35

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)

Answer 36

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

Answer 37

enzyme - lots of types

Answer 38

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

Answer 39

ALL domains of life | - but NEED key to make it possible (attachment)

Answer 40

viruses that infect bacteria • Ex) T4 Phage – infects E. coli bacterium has ribosomes & materials to support viral replication, but a bacterium is also small

Answer 41

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)

Answer 42

- 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)

Answer 43

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

Answer 44

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)

Answer 45

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)

Answer 46

SINGLE (ex: animal virus)

Answer 47

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

Answer 48

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.

Answer 49

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

Answer 50

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

Answer 51

deletion mutation of 32 nucleotides for CCR5

Answer 52

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

Answer 53

Influenza Your cell ``` Hemaglutin. sialic acid HIV gp120 CD4 SARS COV-2 spike protein ACE-2 keys deadbolts ```

Answer 54

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

Answer 55

– 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)

Answer 56

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)

Answer 57

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)

Answer 58

gram - bacterium; virus that infects them are called = BACTERIOPHAGE

Answer 59

– 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

Answer 60

ENDOCYTOSIS | their only option

Answer 61

FUSION OR ENDOCYTOSIS | fuses its envelope containing its spike proteins with the PM of the host cell

Answer 62

- 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

Answer 63

• 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

Answer 64

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)

Answer 65

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

Answer 66

the nucleus

Answer 67

NO - RNA viruses replicate in cytoplasm b/c they bring OWN TOOLS for purpose of replication - do it themselves

Answer 68

* 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

Answer 69

spikes get put on in cytoplasm

Answer 70

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

Answer 71

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

Answer 72

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

Answer 73

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)

Answer 74

– 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

Answer 75

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

Answer 76

Tamiflu/relenza | - inhibit neuramindase activity (so it can't peel)

Answer 77

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

Answer 78

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)

Lecture #2 - Cell Structure & Function PART 3 (after MT) Flashcards

(102 cards)