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infection and immunity > viruses > Flashcards

viruses Flashcards

1
Q

What are viruses classified as?

A

obligate intracellular parasites.

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2
Q

What do viruses need to replicate?

A

host cell’s machinery

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3
Q

Do viruses contain RNA or DNA?

A

Either or but not both

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4
Q

What feature do viruses lack that makes them different from living organisms?

A

lack the ability to reproduce on their own.

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5
Q

Do viruses maintain metabolism to gain energy on their own?

A

No

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6
Q

Are viruses considered alive?

A

No, because they lack key features like independent reproduction and metabolism.

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7
Q

Virus Structures

A

Naked capsid virus
Enveloped virus

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8
Q

What makes naked capsid viruses more virulent?

A

they don’t have an extra lipid membrane.

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9
Q

How do naked capsid viruses typically exit the host cell?

A

Via cell lysis.

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10
Q

Are naked capsid viruses more resistant to extreme conditions?

A

Yes, more resistant to extreme pH, heat, dryness, and simple disinfectants.

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11
Q

How do naked capsid viruses spread?

A

fomites
hand-to-hand
small droplets.

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12
Q

Why can naked capsid viruses survive in the gastrointestinal system?

A

because of their resistance to low pH and bile detergents.

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13
Q

How are naked capsid viruses typically protected against?

A

Antibodies

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14
Q

How does the virulence of enveloped viruses compare to naked capsid viruses?

A

less virulent

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15
Q

Do enveloped viruses always cause cell lysis during cell exit?

A

NOT always

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16
Q

What surrounds the capsid of an enveloped virus?

A

outer membrane (envelope)

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17
Q

How do enveloped viruses form their envelope?

A

Host cell membrane during virus assembly and exit.

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18
Q

How do enveloped viruses avoid immune detection?

A

using the host’s membrane, they avoid cell lysis escape the host’s immune system.

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19
Q

How do enveloped viruses respond to environmental conditions?

A

relatively less sensitive than naked capsid viruses.

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20
Q

How do enveloped viruses spread?

A

large droplets
secretions
organ transplantation
blood transfusion

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21
Q

What are viruses grouped by in morphology?

A

size and shape.

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22
Q

What are the key features of virus chemical composition?

A

may consist of DNA or RNA
may be single or double-stranded
May be linear or circular

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23
Q

Are most DNA viruses single or double-stranded?

A

double-stranded.

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24
Q

Where does replication of DNA viruses occur?

A

nucleus

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25
Q

What must happen before DNA viruses can be synthesized into proteins?

A

must be transcribed

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26
Q

What is an exception for DNA viruses that replicate outside the nucleus?

A

Can replicate in the cytoplasm because they carry their own polymerases. (ex. Poxvirus)

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27
Q

DNA viruses sequens

A

DNA to RNA to mRNA to Proteins

28
Q

Are most RNA viruses single or double-stranded?

A

single-stranded.

29
Q

Where does replication of RNA viruses occur?

A

cytoplasm

30
Q

How do RNA viruses begin synthesizing proteins?

A

can use their RNA to immediately synthesize proteins.

31
Q

Give an example of an RNA virus.

A

Picornavirus

32
Q

RNA Viruses sequens

A

RNA to mRNA to Proteins

33
Q

What is a key feature of Positive (Plus)-Strand RNA viruses?

A

serve as mRNA and can be immediately translated into proteins.

34
Q

POSITIVE(Plus)- STRAND-RNA sequens

A

RNA/mRNA to protiens

35
Q

What is the key feature of Negative (Minus)-Strand RNA viruses?

A

require their viral RNA to be transcribed into mRNA before it can be translated into proteins.

36
Q

What is a retrovirus?

A

special category of RNA viruses that replicate by reverse transcription.

36
Q

NEGATIVE(Minus)-STRAND-RNA sequens

A

RNA to mRNA to protiens

37
Q

How do retroviruses replicate their RNA?

A

use an enzyme called reverse transcriptase to convert their RNA into DNA.

37
Q

What happens after the RNA of a retrovirus is transcribed into DNA?

A

incorporated into the host cell’s genome.

38
Q

What is the role of reverse transcriptase in retroviruses?

A

the enzyme that transcribes the RNA of a retrovirus into DNA.

39
Q

What is an example of a retrovirus?

A

HIV

40
Q

What type of cell does HIV target?

A

Helper T cells

41
Q

What are some common DNA viruses

A

Human papillomavirus (HPV)
Herpes simplex virus (HSV) 1 and 2
Varicella zoster virus (VZV)

42
Q

What are some common RNA viruses

A

Hepatitis C virus
Coronavirus

43
Q

Why must a virus undergo replication?

A

to create new, infectious virions capable of infecting other cells or hosts.

44
Q

What is the first step of virus replication?

A

Attachment - The virus binds to the host cell.

45
Q

How does the virus attach/bind to the host cell?

A

Specific receptor molecules on the host cell’s plasma membrane.

46
Q

What is an example of a virus receptor binding?

A

HIV binds to CD4 receptors on T-cells.

47
Q

What is the second step of virus replication?

A

Penetration - The virus crosses the host cell’s plasma membrane.

48
Q

Does penetration require energy from the host cell?

A

Yes

48
Q

How does the virus enter the host cell?

A

Via endocytosis or phagocytosis.

49
Q

What is the third step in virus replication?

A

Uncoating - Breakdown or removal of the capsid to release the virus genome.

50
Q

Where does the virus genome go after uncoating?

A

Released into host cell to be used for replication and transcription.

51
Q

What is the fourth step in virus replication?

A

Replication – The virus genome is copied.

52
Q

What happens during the replication step of viral replication?

A

Proteins being incorporated into the virion are made by expressing viral genes, and the virus genome is copied.

53
Q

What is the purpose of replication in the viral life cycle?

A

To generate the necessary components (viral proteins and genome) to assemble new virions.

54
Q

What is the fifth step in virus replication?

A

Assembly – Newly synthesized viral components are collected and assembled into immature virus particle.

55
Q

Can assembly occur simultaneously with other steps in virus replication?

A

Yes, assembly can occur alongside maturation and release.

56
Q

What is the process of maturation in viral replication?

A

Changes in the immature virion(capsid), resulting in an infectious virus particle, ready to infect other cells.

57
Q

What is the final step in the virus replication cycle?

A

Release, the virion is released from host cell, into the extracellular environment, continuing the cycle of infection.

58
Q

How can the release of a virus occur?

A

Budding
Depending on the virus.

59
Q

What happens during the lytic cycle?

A

New virions are produced, and the bacterial cell undergoes lysis, releasing more bacteriophages.

60
Q

What is the latent period in the lytic cycle?

A

the time between the infection of the host cell and the cell’s lysis.

61
Q

What happens during the lysogenic cycle?

A

The viral DNA is incorporated into the host DNA.

62
Q

What is the dormant period in the lysogenic cycle?

A

when the host cell lives and does not show any signs of infection.

63
Q

How does the viral DNA behave in the lysogenic cycle?

A

integrates into the host’s genome and remains dormant until triggered to enter the lytic cycle.

infection and immunity (10 decks)

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