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Microbiology Exam One > Viruses > Flashcards

Flashcards in Viruses Deck (39):
1

What is a virus?

Minuscule, acellular infectious agent having either DNA or RNA

2

What is the cause of most of the diseases that plague the industrialized world?

Viruses

3

When the virus exists in an extracellular state, what is it called?

Virion

4

What is the name of the virus's protein coat that surrounds the nucleic acid core?

Capsid

5

The capsid together with the nucleic acid core is called what?

Nucleocapsid

6

What is the outer structure of the virus that encloses the nucleocapsids of some other viruses?

Phospholipid envelope

7

What is the purpose of the phospholipid envelope of viruses?

Provide protection for viral nucleic acid and means of attachment to host cells

8

Once in the intracellular state, what happens to the virus structure?

Uncoating occurs and the capsid is removed leaving the virus to exist simply as nucleic acid

9

What kind of virus only infects a particular kind of cell in a particular host? (Ex. = HIV infecting helper T cells)

Specific

10

What kind of virus can infect many kinds of cells in many different hosts?

Generalists

11

What types of organisms are susceptible to some sort of viral attack?

ALL types (even other viruses!)

12

What virus is a classic example of a "bullet-shaped" virus?

Rabies

13

What is the most common viral shape?

Icosahedron (20 sided dome)

14

What is the shape of a polyhedral virus?

Geodesic dome

15

What is the shape of a helical virus?

Spiral

16

What is the shape of a complex virus?

Capsids of many shapes

17

What is a bacteriophage?

A virus that attacks bacteria

18

How is the viral envelope of a virus obtained?

Acquired from host cell during viral replication or release

19

What are the viral glycoproteins that project on the viral envelope called?

Spikes

20

What is the purpose of the viral envelope?

Provides protection, plays role in host recognition, and helps viruses enter host cells

21

What is lytic replication?

Replication cycle usually resulting in death and lysis of host cell

22

What is lysogeny?

Modified replication cycle where infected host cells grow and reproduce normally for generations before they lyse

23

What are the inactive phages called during lysogeny?

Prophages

24

What is lysogenic conversion?

When phages carry genes that alter the phenotype of a bacterium that can change it from being harmless to a pathogen

25

Why is viral replication different in animal cells?

Presence of envelope, eukaryotic nature of cells, and lack of cell wall

26

Replication of animal viruses is guided by what?

Chemical attraction

27

What are the attachment molecules that mediate attachment for animal viruses?

Glycoprotein spikes

28

What are the three mechanisms of entry of animal viruses?

Direct penetration, membrane fusion, and endocytosis

29

What are latent viruses or proviruses?

Animal viruses that remain dormant in host cells

30

What is the inexpensive way to culture viruses in the laboratory?

In embryonated chicken eggs

31

What is a prion?

Proteinaceous infectious agent that lacks nucleic acid

32

Where is cellular PrP protein found, and what does it look like?

Made by all mammals and is a normal structure with alpha-helices

33

What is a prion PrP?

Disease-causing form with beta-sheets

34

How can prions be destroyed?

Incineration or autoclaving in sodium hydroxide

35

What does prion PrP do to cellular PrP?

Converts it into prion PrP by inducing conformational change

36

In what body system is prion expression most predominant?

Nervous system (possible elsewhere, however)

37

What are prion diseases in the nervous system?

Formation of large vacuoles in the brain that are characteristically spongy in appearance

38

What are examples of spongiform encephalopathies?

BSE, vCJD, Kuru

39

Prions composed of different proteins may lie behind what other muscular and neuronal degenerative diseases?

Alzheimer's disease, Parkinson's disease, and ALS