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Microbio > Unit 3: Chapter 25 > Flashcards

Unit 3: Chapter 25 Flashcards

1
Q

Viruses

A
  • Obligate intracellular parasites
  • Cannot reproduce independently
  • Can infect all cell types
  • Are not living organisms and not composed of cells
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2
Q

why do viruses typically infect only a single tissue type

A

location of compatible receptors (viruses not infecting random host)

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3
Q

Baceriophages will not infect human because

A

receptors are not matched

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4
Q

True or False: viruses can have both DNA and RNA

A

False

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4
Q

Viruses are made of

A

Comprised of DNA OR RNA surrounded by capsid (protein coat) and/ or envelope derived from a host cell

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5
Q

Virion

A

Outside the host cell
Have capsid for protection

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6
Q

Capsid

A

Protein coat for protection outside nucleic acid

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7
Q

Where do viruses get envelopes from?

A

Arise from plasma or organelle membranes of HOST CELL

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8
Q

In order for viruses to make more progeny, it needs

A

More virons by more nucleic acids
More capsid by more nucleic acids and protein coat

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8
Q

Why do viruses take over host cell?

A

To act like living with taking over host metabolism in order to make more progeny

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9
Q

Spike protein

A

Important in virion attachment to host cell surface

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10
Q

Virus Classification based on:

A
  1. Nucleic acid type
  2. Presence of absence envelope
  3. Capid symmetry
  4. Dimensions of Viroid and capsid
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11
Q

Viral mRNA

A

Original RNA sequence

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12
Q

Positive strand RNA

A

Same sequence mRNA

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13
Q

Negative strand RNA

A

Compementary mRNA sequence
A –> U

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14
Q

Negative strand DNA

A

Complementary DNA sequence
A –> T

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14
Q

Positive strand DNA

A

Same mRNa with thymine for uracil

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15
Q

Baltimore System of Classification

A

Organize viruses based on their genome type and the mechanisms used to synthesize mRNA and replicate their genomes
7 Groups of genomes

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16
Q

Lytic cycle

A

Results in lysis of host cell and destroys host

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17
Q

Virulent phages

A

Viruses that lyse their host at end of viral life cycle and host cell will be killed

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18
Q

Lysogenic cycle

A

When phage DNA is incorporated into the host chromosomal DNA
Phase of temperate virus life cycle where it establishes and maintains lysogeny
Does not destroy host cell

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19
Q

Lysogeny

A

State in which viral genome remains within a cell after infection and reproduces along with it
Does not destroy host cell

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20
Q

Temperate phages go through:

A
  1. Lytic cycle: enter host and lyse
  2. Lysogenic cycle: remain within host without destroying it
  3. Can also do both with switching from either
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21
Q

Double Stranded DNA viruses (ds DNA viruses)

A

Largest group of known viruses
Infect all cell types
Only group of viruses that synthesize DNA and RNA

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22
Q

Double Stranded DNA viruses Baltimore System

A

Genome replication: dsDNA –> dsDNA
Protein synthesis: dsDNA –> mRNA –> Protein

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23
Q

Escherichia virus T4: Virulent bacteriophage

A

Virulent (lytic) dsDNA phage
Kills host cell immediately
Phage Life cycle culminates with host cell bursting and releasing virion

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24
Q

Escherichia virus T4 Life Cycle

A
  • Transcription –> early mRNA used for things required urgent (Ex. enzymes like DNA dependent polymerase)
  • Transcription –> late mRNA used for things not needed immediately and for late stages of infections (Ex. Genes code for capsid)
25
Q

How is T4 genome expression is regulated?

A

Early and late gene products clustered separetly

26
Q

Escherichia virus lamda

A

Temperant bacteriophage
Can enter lytic or lysogenic cycle upon infection of host

27
Q

Lamda Phage DNA

A

Linear dsDNA with cohesive ends that make circular DNA
Includes cll activator

28
Q

cll activator

A

plays important role in determining lamda phase will establish lysogeny or follow lytic cycle for temperant phage

29
Q

cll levels high indicate

A

lysogenic cycle

30
Q

cll levels low indicate

A

lytic cycle

31
Q

Induction

A

events trigger virus to switch from lysogenic to lytic cycle

32
Q

Lysogenic conversion

A

Phage genes cause production of enzymes and toxins that cause pathology
(Harmless bacteria to pathogenic)

33
Q

Diphtheria toxin

A

Example of lysogenic conversion
Responsible for deadly nature disease in bacteriophage product
Without phage is harmless

34
Q

Single stranded DNA Viruses (Ss DNA) viruses)

A

Genome replication: ssDNA –> dsDNA –> ssDNA
Protein synthesis: ssDNA –> dsDNA –> mRNA –> Protein

35
Q

Double stranded RNA Viruses Baltimore System

A

Genome replication: dsRNA –> ssRNA –> dsRNA
Protein synthesis: dsRNA –> mRNA –> Protein

36
Q

All RNA viruses must produce

A

RNA dependent RNA polymerase (RdRp)

37
Q

RNA dependent RNA polymerase (RdRp)

A

RNA polymerase uses an RNA polymerase as template for DNA synthesis

  1. Replicase: replicate viral RNA genomes
  2. Transcriptase: make genomes
38
Q

Positive Strand RNA Viruses Baltimore System

A

Genome replication: +RNA –> -RNA –> +RNA
Protein synthesis: +RNA –> -RNA –> mRNA –> Protein

39
Q

Positive Strand RNA Viruses

A

have genomes that act as mRNA and be translated upon entry into host cell

Ex. Coronavirus, SARS-CoV-2

40
Q

SARS-Cov-2

A

+ single strand RNA virus
spike proteins fits in ACE2 receptor and is cleaved by TMPRSS2 which releases genome in cell cytoplasm
Polyproteins represent

41
Q

Polyproteins

A

Large protein that is cleaved into smaller functional proteins by proteases

42
Q

Polyproteins in Coronavirus

A

Polyprotein 1a: enable virus to exploit most cell resources
Polyprotein 1ab: act during genome replication
Progeny is released by exocytosisn

43
Q

Tobacco Mosaic Virus (TMV)

A

+ single stranded RNA virus
Plant viruses that are positive

44
Q

Plant viruses

A

Multiplication depends on virus’s ability to spread throughout the plant

45
Q

Negative strand RNA viruses baltimore system

A

Genome replication: -RNA –> +RNA –> -RNA
Protein synthesis: -RNA –> mRNA –> Protein

46
Q

Negative strand RNA viruses

A

Cannot serve as mRNA to form viral proteins
must bring one RNA dependent RNA polymerase

47
Q

Influenza Virus

A

Negative strand RNA viruses
Contains 8 segments of RNA for recombination of genome to occur
Shuttle between nucleus and cytoplasm using nuclear localization signals

48
Q

DNA polymerase is in nucleus so DAN viruses need to enter _____ to use our DNA polymerase

ON EXAM

A

our nucleus

49
Q

RNA viruses stay in _____ in host cell

A

Cytoplasm

50
Q

Hemaglutinin (HA)

A

Influenze virus
Spike proteins which enhance attachment to host cells

50
Q

Neuraminidase (NA)

A

Influenze virus
Spike protein
Enzymes that break down sialic acid (componets of host cell membrane)

51
Q

Segemented genome faciliates the development of

A

New strains through mutation and reassortment

52
Q

Annual epidemic caused by

A

Mutation: drift
Less effect

53
Q

Periodic pandemic caused by:

A

Reassortment: shift
Cause more effect

54
Q

Retroviruses

A

+ stransd viruses that user reverse transcriptase

55
Q

Reverse transcriptase

A

Converts ssRNA into dsDNA

56
Q

provirus

A

dsDNA is integrated into host’s DNA and serves as template for mRNA synthesis and positive strand RNA genome synthesis

57
Q

Retroviruses Baltimore system

A

Genome replication: ssRNA –> dsDNA –> ssRNA
Protein synthesis: ssRNA –> dsDNA –> mRNA –> Protein

58
Q

Hepatitis

A

Inflamation of liver

59
Q

Reverse Transcribing DNA Viruses Baltimore System

A

Genome replication: dsDNA –> ssRNA –> dsDNA
Protein synthesis: dsDNA –> mRNA –> Protein

60
Q

During infection of E. coli by bacteriophage ΦX174, genome replication occurs by the process known as ______.

A

Rolling Circle Replication

61
Q

Upon infecting a host cell, a virulent bacteriophage can enter the ______

A

Lytic cycle only
Virulent –> Lytic

Microbio (18 decks)

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