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Fungal/Virology > LEC 7 - Virus Structure + Function I > Flashcards

LEC 7 - Virus Structure + Function I Flashcards

1
Q

What are all viruses when it comes to being a parasite?

A

Obligate Intracellular Parasites

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2
Q

What makes a virus a virus, making it different from bacteria?

A

No independent metabolism

Host provides ribosomes + energy + all precursor molecules

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3
Q

What does the small size of a virus allow for when it comes to entering a host cell?

A

Filterable agents

Passage through fine pore filters can occur

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4
Q

What is different about the viral replication when compared to other living organisms?

A

Progeny are created in an assembly line

Then quickly released into the host

NO BINARY FISSION

Latent period > Rise > Yeild

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5
Q

What is occurring in the cell during the latent period?

A

Replication

Assembly

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6
Q

What are viruses generally made of?

A

Nucleic acids

Proteins

Lipid-containing envelope

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7
Q

What is the principal component of a virus?

A

Proteins

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8
Q

What are the special enzymes that virus encodes for itself?

A

RNA dependent RNA polymerases for the negative strand RNA virus

Reverses transcriptase for retroviruses

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9
Q

Where are the special viral enzymes encoded?

A

Within the capsid

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10
Q

Term: Capsid

A

Protein covering surrounding core of nucleic acid + enzymes

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11
Q

Term: Capsomeres

A

Small protein subunits typically composed of several small proteins that combine in groups to form the capsid

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12
Q

Term: Virion

A

Complete virus particle

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13
Q

Term: Envelope

A

Membrane-like outer covering of certain viruses

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14
Q

Term: Spikes

A

Cirus proteins embedded in envelope that project from surface

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15
Q

What is the envelope made of?

A

Combination of host membrane with some virus proteins

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16
Q

What is often associated with spikes on a virus?

A

Enzymatic activities

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17
Q

What are the two patterns seen in the nucleic acid genome?

A

Extended nucleic acid form

Condensed nucleic acid form

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18
Q

What is the viral genome made of?

A

RNA

or

DNA

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19
Q

What are the forms of the viral RNA/DNA?

A

Double stranded

Single stranded

Segmented

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20
Q

Which is more stable, DNA or RNA?

A

DNA

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21
Q

What is the positive of having RNA as your genome?

A

Increased rate of replication

Which allows for more mutations, allowing the virus to adapt to the environment more easily

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22
Q

What are the characteristics of positive stranded RNA?

A

Can serve as mRNA directly

Directly translated by host ribosomes into proteins

Hosts understands

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23
Q

What are the characteristics of negative stranded RNA?

A

Must first be transcribed

Via virus-encoded RNA dependent RNA polymerase

Then becomes a positive strand

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24
Q

What is known about viral ancestory?

A

They do not share a common one

25
Q

What are the two features that are used to discribe a virus?

A

Physical features

Biological properties

26
Q

What physical features are used to describe virus?

A

Nature + Physical form of nucleic acid genome

Capsid structure + symmetry

Presence/absence of envelope

27
Q

What biological properties are used to describe viruses?

A

Host range

Transmission mechanism

Tissue tropism

Pattern of replication

28
Q

What phase must all virsuses pass through?

A

mRNA phase

29
Q

What are the basic steps in viral replication?

A

Attachment

Latent period

Burst/Release by budding of progeny virions

30
Q

What is occurring during the latent period?

A

Virus is developing inside the cell but is not readily evident outside the cell

31
Q

What occurs with the cell when a true burst occurs?

A

Death of the host cell

32
Q

Where do DNA viruses tend to repicate and mature in the host?

A

Within the nucleus

33
Q

How do some DNA viruses disrupt the host cell cycle?

A

Change the control of p53 or Rb

Enters “S-like” phase to replicate

34
Q

What is different about the replication process of large, complex DNA viruses?

A

Dont pay attention to host cell cycle

Supply their own host cell-independent DNA replication functions

35
Q

Where does the virus go to be released out of the cell by exocytosis

A

Endoplasmic reticulum

36
Q

Where do RNA viruses tend to replicate and mature in the host?

A

Cytoplasm

37
Q

What is a common problem amoungst RNA viruses?

A

RNA is unstable

Molecules must be copied rapidly and the host doesn’t have the machienery to do so

38
Q

What are the ways an RNA virus handles the issue of the host cell not being able to replicate it?

A

Transport molecules into the host in virion itself

– or –

Synthesized from virus genome

39
Q

What are negative RNA strands need to be read?

A

RNA-dependent RNA polymerase (transcription)

40
Q

How is RNA-dependent RNA polymerase made?

A

Place it within the capsid

Transport pre-formed into the host to start infection

41
Q

What are the three viruses that can move retrograde through neurons?

A

Rabies

Herpes

Polio

42
Q

What are the hallmarks of retroviral replication?

A

Reverse transcription

– and –

Integration

43
Q

How are retroviruses handled within the host cell?

A

Pseudo-diploid RNA virus

Convert RNA to DNA (reverse transcription)

44
Q

Term: Destructive replication

A

One double stranded DNA is substituted for two molecules of single stranded RNA that originally entered the cell

45
Q

What enzyme does the retrovirus need that it encodes for?

A

Reverse transcriptase

(RNA-dependent DNA polymerase)

46
Q

What does reverse transcriptase do?

A

Reverses the flow of genetic information

Allows DNA to be made from RNA

47
Q

How does knowing the process of transmission lead to better control?

A

Effective control often hinges on breaking the chain of transmission

48
Q

Term: Transformation (cancer + virus)

A

Host cells converted to malignant conditions

49
Q

What does a host cell do to transform into a malignant condition?

A

Become immortal

Continue to divide w/o any control

Alter morphology

Lose contact inhibition

50
Q

What are the critical mechanisms when it comes to a cell transforming into a malignant cell line?

A

Inactivation of cell cycle control mechanisms

Providing genese that alter host behavior

Enhancing transcription of key host genes involved in growth

Preventing host from inducing apoptosis

51
Q

What cell types does transformation normally occur in?

A

Non-permissive host cells

52
Q

What happens if the virus is able to proceed through a full growth cycle?

A

Host cell will die

53
Q

How do DNA tumor viruses alter the funciton of p53 or Rb?

A

Produce proteins that antagonize the function of the proteins

Stopping them from suppressing growth

54
Q

What are the “three” methods by which retrovirus transformation occurs?

A

Acute transforming retroviruses

Chronic transforming retroviruses

Indirect method

55
Q

How does the indirect method of retroviral transformation occur?

A

Induction of tissue damage produces mutations

56
Q

Describe: Chronic transforming retroviruses

A

Activate expression of growth-stimulating host genes

Slower induction of cancer

57
Q

Describe: Acute transforming retrovirus

A

Bring in altered forms of genes involved in cell growth control

Drive host out of balance

Acute tumor induction

58
Q

What are the oncogenes involved in acute transforming retrovirals?

A

ras

src

myc

jun

fos

59
Q
A

Fungal/Virology (26 decks)

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