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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
Double Stranded DNA viruses Baltimore System
Genome replication: dsDNA --> dsDNA Protein synthesis: dsDNA --> mRNA --> Protein
23
Escherichia virus T4: Virulent bacteriophage
Virulent (lytic) dsDNA phage Kills host cell immediately Phage Life cycle culminates with host cell bursting and releasing virion
24
Escherichia virus T4 Life Cycle
- 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
How is T4 genome expression is regulated?
Early and late gene products clustered separetly
26
Escherichia virus lamda
Temperant bacteriophage Can enter lytic or lysogenic cycle upon infection of host
27
Lamda Phage DNA
Linear dsDNA with cohesive ends that make circular DNA Includes cll activator
28
cll activator
plays important role in determining lamda phase will establish lysogeny or follow lytic cycle for temperant phage
29
cll levels high indicate
lysogenic cycle
30
cll levels low indicate
lytic cycle
31
Induction
events trigger virus to switch from lysogenic to lytic cycle
32
Lysogenic conversion
Phage genes cause production of enzymes and toxins that cause pathology (Harmless bacteria to pathogenic)
33
Diphtheria toxin
Example of lysogenic conversion Responsible for deadly nature disease in bacteriophage product Without phage is harmless
34
Single stranded DNA Viruses (Ss DNA) viruses)
Genome replication: ssDNA --> dsDNA --> ssDNA Protein synthesis: ssDNA --> dsDNA --> mRNA --> Protein
35
Double stranded RNA Viruses Baltimore System
Genome replication: dsRNA --> ssRNA --> dsRNA Protein synthesis: dsRNA --> mRNA --> Protein
36
All RNA viruses must produce
RNA dependent RNA polymerase (RdRp)
37
RNA dependent RNA polymerase (RdRp)
RNA polymerase uses an RNA polymerase as template for DNA synthesis 1. Replicase: replicate viral RNA genomes 2. Transcriptase: make genomes
38
Positive Strand RNA Viruses Baltimore System
Genome replication: +RNA --> -RNA --> +RNA Protein synthesis: +RNA --> -RNA --> mRNA --> Protein
39
Positive Strand RNA Viruses
have genomes that act as mRNA and be translated upon entry into host cell Ex. Coronavirus, SARS-CoV-2
40
SARS-Cov-2
+ single strand RNA virus spike proteins fits in ACE2 receptor and is cleaved by TMPRSS2 which releases genome in cell cytoplasm Polyproteins represent
41
Polyproteins
Large protein that is cleaved into smaller functional proteins by proteases
42
Polyproteins in Coronavirus
Polyprotein 1a: enable virus to exploit most cell resources Polyprotein 1ab: act during genome replication Progeny is released by exocytosisn
43
Tobacco Mosaic Virus (TMV)
+ single stranded RNA virus Plant viruses that are positive
44
Plant viruses
Multiplication depends on virus's ability to spread throughout the plant
45
Negative strand RNA viruses baltimore system
Genome replication: -RNA --> +RNA --> -RNA Protein synthesis: -RNA --> mRNA --> Protein
46
Negative strand RNA viruses
Cannot serve as mRNA to form viral proteins must bring one RNA dependent RNA polymerase
47
Influenza Virus
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
DNA polymerase is in nucleus so DAN viruses need to enter _____ to use our DNA polymerase ON EXAM
our nucleus
49
RNA viruses stay in _____ in host cell
Cytoplasm
50
Hemaglutinin (HA)
Influenze virus Spike proteins which enhance attachment to host cells
50
Neuraminidase (NA)
Influenze virus Spike protein Enzymes that break down sialic acid (componets of host cell membrane)
51
Segemented genome faciliates the development of
New strains through mutation and reassortment
52
Annual epidemic caused by
Mutation: drift Less effect
53
Periodic pandemic caused by:
Reassortment: shift Cause more effect
54
Retroviruses
+ stransd viruses that user reverse transcriptase
55
Reverse transcriptase
Converts ssRNA into dsDNA
56
provirus
dsDNA is integrated into host's DNA and serves as template for mRNA synthesis and positive strand RNA genome synthesis
57
Retroviruses Baltimore system
Genome replication: ssRNA --> dsDNA --> ssRNA Protein synthesis: ssRNA --> dsDNA --> mRNA --> Protein
58
Hepatitis
Inflamation of liver
59
Reverse Transcribing DNA Viruses Baltimore System
Genome replication: dsDNA --> ssRNA --> dsDNA Protein synthesis: dsDNA --> mRNA --> Protein
60
During infection of E. coli by bacteriophage ΦX174, genome replication occurs by the process known as ______.
Rolling Circle Replication
61
Upon infecting a host cell, a virulent bacteriophage can enter the ______
Lytic cycle only Virulent --> Lytic

Microbio (18 decks)

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