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BIO 112 > Ch 21 > Flashcards

Ch 21 Flashcards

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Biology 101 flashcards
1
Q

Founders of the virus

A

Dmitiri Ivanovsky, then Martinus Beijerinck

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2
Q

How did Dmitri Ivanovksy isolate the virus

A

filtered sap from an infected tobacco plant that could still infect a healthy tobacco plant because it contained tobacco mosaic virus. Later identified that the infectious agent was a virus, not bacteria

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3
Q

what did Martinus beijerinck do?

A

He repeated Ivanovsy’s work and applied germ theory, and to an extent, Kock’s postulates, basically that microorganisms (pathogens/germs) were the cause of specific diseases

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4
Q

Technology that made viruses visible

A

electron microscope

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5
Q

Size of virus

A

incredibly small

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6
Q

Parts of a virus

A
  1. Capsid (outer protein coat)
  2. nucleic acid genome (RNA/DNA)
  3. envelope: membrane covering the capsid, outermost layer (not all viruses)
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7
Q

can viruses replicate by themselves?

A

no, they need “cellular machinery” of host cells to survive and replicate

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8
Q

how do we detect viruses?

A

PCR (polymerase chain reaction) and immunoassays (using antibodies)

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9
Q

3 main hypotheses of how viruses came to be

A

H1: Devolution or regressive (ancestors of viruses were once more complex organisms that lost genetic material over time as they adapted to a parasitic lifestyle)
H2: Escapist or progressive (pieces of RNA and DNA that escaped from a host cell and gained the ability to move between cells)
H3: Virus first (viruses existed before all life as self-replicating entities that over time became more organized and complex)

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10
Q

Four virus shapes

A
  1. filamentous (long, thin worm shape)
  2. enveloped (have an outer membrane that covers capsid)
  3. isometric/icosahedral (spherical hexagon shape)
  4. head & tail/complex (infect bacteria and have a head similar to icosahedral and tail like helical, also known as bacteriophage)
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11
Q

bacteriophage function, T4 function

A

infect bacteria, infects bacterium, escherichia coli (E. coli), has a DNA genome

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12
Q

adenovirus function

A

infects human respiratory tract, no envelope

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13
Q

examples of non-enveloped viruses

A

Adenovirus, poliovirus, HPV (human papillomavirus), and hepatitis A virus, HIV retrovirus.

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14
Q

HIV retrovirus function

A

causes AIDs, is enveloped, is a retrovirus (reverse transcribe its RNA genome into DNA form), basically, the virus’s genetic info is in the form of RNA, virus will inject RNA into host cell, then RNA will transcribe to DNA, and host cell will continue to replicate it.

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15
Q

do DNA or RNA viruses mutate quicker? why?

A

RNA because RNA polymerase is not as accurate as DNA polymerase, also, RNA polymerases dont have good proofreading mechanisms, so they have more mutations that allow it to mutate quickly and have more errors.

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16
Q

4 ways to classify viruses

A
  1. nucleic acid type and function
  2. capsid structure
  3. enveloped/non-enveloped
  4. genome structure
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17
Q

Baltimore Classification System

A

current system for classifying viruses, seven categories: (double & single stranded DNA, double RNA, single RNA +, single RNA -, double DNA reverse, single RNA reverse.

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18
Q

DNA viruses

A

usually double stranded, replication in nucleus but can do it in cytoplasm if have DNA polymerase, smallpox virus

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19
Q

RNA viruses,

A

usually single stranded, replication in cytoplasm, high mutation rates bc RNA polymerase doesn’t have proofreading, influenza, coronavirus

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20
Q

what 3 things can happen when a virus replicates in a host cel??

A
  1. lysis (cell ruptures open)
  2. apoptosis (programmed cell death)
  3. widespread symptoms due to body’s immune response
21
Q

budding

A

allows enveloped virus to leave host cell without causing immediate apoptosis, allows virus to avoid immune system detection and efficiently spread

22
Q

steps of virus infections

A
  1. attachment
  2. entry
  3. replication and assembly
  4. egress (release)
23
Q

Attachment (

A

step 1. receptors on surface of host cell bind to proteins on virus capsid or glycoproteins on virus envelope, very specific

24
Q

entry

A

step 2. virus can inject bare DNA into host cell “naked” or enter eukaryotic cells by endocytosis, break down the vesicle, envelop, and capsid, releasing free DNA.

25
Q

Egress (release_

A

step 4. may involve lysis and death of host cell, or budding which does not kill the host cell

26
Q

most bacteriophages are _____ viruses

A

dsDNA viruses (double stranded)

27
Q

lytic vs. lysogenic cycle

A

Lytic Cycle: phage infects cell, phage DNA circularizes separately from host DNA, replicates and makes new phages, cell lyses and releases phages.
Lysogenic Cycle: phage infects cell, phage DNA incorporated into host genome, cell divides and passes phage DNA to daughter cells.

28
Q

Animal viruses can cause (5)

A
  1. acute disease
  2. chronic
  3. latency and intermittent symptoms
  4. asymptomatic
  5. oncogenesis
29
Q

what virus causes covid-19, desciribe

A

Sars-CoV-2. enveloped, non-segmented, positive sense stranded RNA virus

30
Q

diagnostic testing

A
  1. molecular test: examine genetic material for virus (PCR-curative)
  2. antigen test: to detect protein on the surface of the virus (antigen)`
31
Q

what type of test is the bin home test

A

diagnostic: antigen test

32
Q

what kind of test is PCR

A

diagnostic: molecular

33
Q

antibody test

A

tests YOU, not the virus, looks for antibodies to determine if you have been infected in the past or been vaccinatedwlhat

34
Q

what are fusion inhibitors

A

antiviral drugs that prevent virus from fusing with host cell membrane

35
Q

what are reverse transcriptase inhibitors

A

reverse transcriptase is an enzyme found in retroviruses, which converts RNA to DNA. The inhibitors stop this process from occurring. Only effective for retroviruses.

36
Q

what are protease inhibitors

A

protease is an enzyme that helps produce mature and infectious viral particles. the inhibitor stops this process.

37
Q

what are integrase inhibitors

A

insertion of viruses’ genome into host cell’s genome. inhibitor stop this process.

38
Q

tamiflu function

A

inhibits Neuraminidase (NA), which stops the release of viral particles from exiting the cell and infecting other host cells

39
Q

six stages of developing vaccines

A
  1. discovery
  2. testing in cell cultures or animals models
  3. clinical human testing
  4. effectiveness and dosage
  5. approval process
  6. manufacturing and quality control
40
Q

why do we sometimes need annual updated vaccines?

A

many viruses are RNA viruses, which mutate frequently bc the protein changes

41
Q

horizontal vs vertical transmission in plants

A

Horizontal: (plant to plant) virus typically enters through damaged plant tissue or from pollen or insect bites, no seeds are involved
Vertical: through the seed, virus is transmitted from parent plant, can cause hypoplasia (underdevelopment) or necrosis of plant/plant tissue

42
Q

what are prions?

A

proteinaceous infectious particles are misfolded proteins, can cause misfolding in normal proteins they come across. ARE NOT VIRUSES, contain NO nucleic acids. cause fatal neurodegenerative diseases

43
Q

Mad cow disease (prion)

A

BSE (bovine spongiform encephalopathy), cause spongelike brain tissue in cattle(

44
Q

(v)Creutzfeldt-Jakob disease

A

misfolding of proteins in the brain (humans)

45
Q

Kuru (spread by cannabilism)

A

ingestion of contaminated human brain tissue

46
Q

Scrapie (in sheep)

A

spongiform encephalopathy in sheep and goats

47
Q

Chronic Wasting Disease

A

spongiform encephalopathy in deer moose elk

48
Q

Viroids

A

small circles of RNA (not virus), only infects plants and causes crop failure, can replicate within cells and does not encode proteins

49
Q
A

BIO 112 (12 decks)

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