viruses Flashcards

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1
Q

General information

A
  • microscopic
  • pathogenic
    consist of:
  • genetic material (DNA/RNA)
  • capsid (protein coating around genetic mat)
  • envelope (has protein markers on it- not all have this)
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2
Q

Virus reproduction (how + steps)

A

viruses invade a host cell and use the cells machinery to reproduce themselves

3 step of viral infection:
- attachment & penetration
- viral genome expression and replication
- assembly and release of new viruses

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3
Q
  1. Attachment & Penetration
A

viral attachment:
virus attaches to + enters the host cell

  • the virus has specific “keys” to “unlock” specific types of cells
    (viruses are specific to their hosts)
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4
Q

how are viruses specific to their host

A

1) protein on the viral envelope signal specific types of cells to let them in
2) protein match their hosts cells like a lock & key

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5
Q

three ways the virus can enter the cell

A

a) punch a hole into the cell and inject their DNA
b) fuse their envelope with the cell membrane, allowing DNA inside
c) become phagocytosed (engulfed) by the host cell

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6
Q

phagocytosis

A

when one cell engulfs another cell of virus whole

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7
Q

bacteriophage

A
  • also called “phage”
  • a virus that infects bacteria
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8
Q

name the two types of viral life cycles and characteristics

A

1) Lytic cycle: shorter-term illness
2) Lysogenic cycle: long-term, dormant viruses

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9
Q

lytic cycle (simple explanation)

A

the host cell is used to replicate the virus and then the host cell is killed

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10
Q

lytic cycle steps (5)

A

1) attachment: specific receptor proteins on viral envelope match virus to the host cell
2) penetration: viral genome is inserted into the host cell
3) biosynthesis: host cell machinery is used to copy, transcribe and translate viral genome, which encodes the building materials for new viruses and the viral assembly proteins
4) assembly: new viruses are put together
5) release: new viruses break open (kill=lyse) host cell, and new viruses are released to infect other cells

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11
Q

lysogenic cycle (simple explanation)

A

viral genome is incorporated into the hosts genome

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12
Q

lysogenic cycle steps (3)

A

1) virus attaches and genome enters host cell
2) viral DNA is inserted into hosts DNA
3) prophage is replicated when host cell replicates ( eventually prophage DNA leaves host DNA and enters lytic cycle)

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13
Q

what is prophage

A

integrated genome

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14
Q

dormant lysogenic infections

A
  • during the lysogenic replication process, the virus appears dormant because the host does not get sick
  • when the virus exits the lysogenic cycle, many cells are already infected therefore progression of the disease is much faster
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15
Q

examples of lysogenic cycle human viral infections (4)

A
  • Herpes simplex (herpes, cold sores)
  • Varicella Zoster Virus (shingles)
  • Human Papilloma Virus (Warts)
  • Human Immunodeficiency Virus (HIV) (AIDS)
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16
Q

timeline of lysogenic cycle viruses

A

host typically doesn’t show symptom for an extended period of time after being infected (could be months or years)

17
Q

examples of lytic cycle human viral infections (4)

A
  • common cold
  • influenza
  • rabies
  • tobacco mosaic virus
18
Q

timeline of lytic cycle viruses

A

host typically displays symptoms 3-14 days after being infected

19
Q

why are viruses non-living (6)

A
  • don’t have their own energy metabolism
  • don’t grow
  • don’t reproduce on their own
  • don’t waste products
  • don’t respond to stimuli
  • inactive until they invade a host cell
20
Q

positive uses for viruses

A
  • have helped scientists understand new things about how DNA is used in the body
  • used to manipulate DNA in model organisms
  • control of harmful organisms in agriculture
  • use as a capsule to deliver drugs to specific cells
  • genetherapy
  • virotherapy
21
Q

gene therapy

A

use viruses to insert a good gene into someone with a genetic defect or disorder

22
Q

explain the process of gene therapy

A

1) cells harvested from patient
2) in lab, virus altered so cannot reproduce
3) a gene is inserted into the virus
4) altered virus mixer with patients cells
5) cells become genetically altered
6) altered cells injected into patients body
7) altered cells produce desired protein

23
Q

gene therapy might cure…

A
  • diabetes
  • cystic fibrosis
  • cancer
  • hemophilia
  • etc
24
Q

virotherapy (simple definition)

A

cancer prevention and control
- design a virus that will cause the death of cancer cells

25
Q

virotherapy methods (2)

A

1) triggering the immune system to attack the cancer cells
2) making a lytic virus that will specifically infect cancer cells- and cause lysis in those cells only

26
Q

oncolytic virus (definition)

A

a virus that specifically attacks and kills cancer cells

27
Q

challenges in virus-based therapy (3)

A
  • pre-existing immunity to the viral vector
  • a strong immune response to the treatment could cause severe illness or death
  • if the virus inserts into another gene in the patient, could create new problems
28
Q

two similarities and differences between lytic and lysogenic cycle (theses are my own practice questions, answers may be wrong)

A

similarities:
- both are mechanisms of viral reproduction
- both reproduce thousands of copy’s of the original virus
- both only occur within the host cell

differences:
- lytic short term vs lysogenic long term
- lytic kills the host cell vs lysogenic doesn’t
- lytic show symptoms fast after being infected vs lysogenic does not

29
Q

two similarities and differences between genetherapy and virotherapy (theses are my own practice questions, answers may be wrong)

A

-

30
Q

study the image

A