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BS240—Microorganisms & their Human Hosts > Viruses > Flashcards

Viruses Flashcards

1
Q

what are some characteristics of viruses?

A

miniscule

acellular

have DNA or RNA

cause infection in humans, animals, plants, bacteria

no metabolic pathway

cause most diseases in industrialized world

neither grow nor respond to environment

obligate intracellular parasites (can’t reproduce independently)

no cytoplasmic membrane, organelles, cytoplasm

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2
Q

examples of virus families & what they can cause

A

Paramyxoviridae - mumps

Coronaviridae - covid-19

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3
Q

one virus particle

A

virion

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4
Q

nucleic acid surrounded by protein coat

A

nucleocapsid

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5
Q

how can viral genomes differ from one another?

A

DNA or RNA
linear or circular

one piece or segmented

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6
Q

the capsid is made of __________

A

capsomeres

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7
Q

what is the difference between naked & enveloped viruses?

A

enveloped have a phospholipid bilayer around their nucleocapid acquired from a host cell

naked do not

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8
Q

are naked or enveloped viruses tougher?

A

naked

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9
Q

do naked or enveloped viruses have more of an advantage inside the host?

A

enveloped

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10
Q

what are an enveloped virus’s advantages?

A

hides it from immune system

can fuse with cell membrane to infect it

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11
Q

what can damage an enveloped virus?

A

heat, freezing, pH change, chemical disinfectants, lipid solvents

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12
Q

what do some viruses have that help them attach to host cells?

A

glycoprotein spikes

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13
Q

3 virus shapes

A

icosahedral

helical

complex

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14
Q

5 steps of animal virus replication

A

attachment

penetration & uncoating

synthesis of viral proteins & replication of genome

assembly

release

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15
Q

viruses need __ receptors on a cell’s surface to attach

A

2

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16
Q

how do enveloped vs naked viruses attach?

A

enveloped - spikes attach to cell’s receptors

naked - capsid attaches to cell’s receptors

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17
Q

how do nakes vs enveloped viruses attach?

A

naked: capsid attaches to receptors on cell
enveloped: protein spikes attach to receptors on cell

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18
Q

how do enveloped viruses penetrate cell?

A

fusion with cell membrane

endocytosis

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19
Q

how do naked viruses penetrate cell?

A

direct penetration - genome directly through cell membrane

endocytosis

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20
Q

explain uncoating

A

viral nucleic acids and enzymes are released from protein coat

RNA remains in cytoplasm, DNA goes to nucleus

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21
Q

explain replication of DNA viruses

A

mostly occurs in nucleus

virus encodes its own enzymes - DNA polymerase

may embed themselves in host’s genome and become latent viruses/proviruses

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22
Q

explain replication of RNA viruses

A

occurs in cytoplasm

uses viral enzyme replicase (same as RNA polymerase)

many mutations occur (lack of proofreading)

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23
Q

explain reverse transcribing viruses

A

used by retroviruses

encodes enzyme reverse transcriptase

synthesizes DNA from a strand of RNA

also become proviruses/latent viruses

24
Q

examples of reverse transcribing viruses

A

HIV

HTLV

25
Q

examples of RNA viruses

A

influenza

SARS-CoV-2

26
Q

examples of DNA viruses

A

herpes

human papilloma virus

27
Q

explain assembly

A

virus particles assembled to form viruses

28
Q

what are the 2 types of release?

A

budding - used by enveloped viruses - triggers apoptosis

lytic cycle - used by naked viruses - body’s immune defenses may lyse infected cell

29
Q

what are the 2 types of viral infection?

A

acute - sudden onset, short duration

persistent - lasts years to life

30
Q

what are 2 types of persistent infection, and examples?

A

chronic - continuous production of viral particles - Hepatitis B

latent - viral genome remains silent in cell until triggered to reactivate - herpes

31
Q

pathogenesis of herpes

A

initially affects epithelial cells - slow-spreading skin lesions

then infectsneurons - travels up neurons into specific ganglia

32
Q

viruses caus ___% of human cancers

A

20-25%

33
Q

what are oncogenes?

A

genes that can transform a cell into a tumor cell

34
Q

how can viruses cause cancer? (3 ways)

A

carry copies of oncogenes in their genomes

promote oncogenes in host

interfere with tumor repression

35
Q

6 examples of cancer-causing viruses and their cancers

A

human papillomavirus (HPV) - cancer of cervix, vulva, vagina, penis, anus, oropharynx

hepatitis B - liver cancer

hepatitis C - liver cancer

Epstein-Barr - cancer of nasopharynx, Burkitt lymphoma

herpesvirus type 8 - Kaposi sarcoma

human t-lymphocyte virus (HTLV) - leukemia, lymphoma

36
Q

2 ways we can grow viruses

A

human cell culture

embryonated chicken eggs

37
Q

common cold infects the…

A

upper respiratory tract

38
Q

common cold viruses

A

rhinoviruses

coronaviruses

adenoviruses

39
Q

pathogenesis of common cold

A

respiratory epithelial cell destruction

40
Q

common cold transmission & incubation

A

droplet, direct, indirect, airborne (maybe)

24-48hrs

41
Q

what is the biggest health concern with common colds?

A

secondary infections

42
Q

influenza infects…

A

upper & lower respiratory tract

43
Q

type of influenzavirus

A

A, B, C in humans

44
Q

influenza pathogenesis

A

destroys respiratory epithelium

45
Q

transmission & incubation of influenza

A

droplet, direct, indirect, airborne (likely)

48hrs

46
Q

antivirals for influenza work during _______ stages and include 2 drugs:

A

early stages

Tamiflu

Zofluza

47
Q

2 types of protein spikes on influenzaviruses

A

hemagglutinin

neuraminidase

48
Q

this type of influenza caused the Spanish Flu and Swine Flu outbreaks

A

H1N1

49
Q

2 mechanisms by which influenzavirus mutates

A

antigenic drift - random mutations occuring in types A & B

antigenic shift - mixture of genes from two strains of type A

50
Q

what can cause gastroenteritis?

A

norovirus

rotavirus

other microbes

51
Q

gastroenteritis transmission

A

fecal-oral

52
Q

gastroenteritis pathogenesis

A

destroys epithelium of small intestine

interferes with secretion and absorption of fluid and nutrients

53
Q

What is R0?

A

reproductive ratio

how many people one person can infect

54
Q

What is SI?

A

series interval

period of time from first symptoms of person 1 to first symtoms of person 2

55
Q

which cells does SARS-CoV-2 target?

A

Type II pneumocytes

56
Q

what are signs and symptoms of Covid-19?

A

dyspnea (SOB, increased respiration rate)

hypoxemia

productive cough

fever

tachycardia

systemic inflammatory response syndrome

hypotension

multisystem organ failure

BS240—Microorganisms & their Human Hosts (5 decks)

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