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Medical Microbiology 1-15 > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

Some DNA and RNA viruses can transform normal cells into cancer cell. What are these viruses called?

A

Oncogenic viruses.

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2
Q

The cells that are capable of being transformed possess one or more types of these genes. Which are they?

A

The protooncogenes.

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3
Q

What is the name of the tumour producing RNA viruses?

A

Retroviruses

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4
Q

True of false. The ssDNA is used to form dsDNA

A

True

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5
Q

True or false. The ssRNA is transcribed into ssDNA by the enzyme RNa dependent DNA polymerase also called reverse transcriptase.

A

True

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6
Q

The dsDNA can enter the nucleus and become incorporated into what?

A

The host genome.

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7
Q

How are viruses released?

A

By budding from the membrane

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8
Q

How many mechanisms by which the retrovirus induce malignancies? Name the viruses.

A

Two. The Rous sarcoma virus (RSV) (infects chickens) and Avian leukosis virus (infects birds).

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9
Q

Define reverse transcriptase

A

An enzyme that catalyzes the formation of DNA from an RNA template in reverse transcription.

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10
Q

Name the four genes that are on the ssRNA of the Rous sarcoma virus. Where are they located?

A

gag codes= found in the capsid
pol codes for the reverse transcriptase
env codes for 2 glycoproteins
src codes for an enzyme that phosphorylate cellular proteins.

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11
Q

How many genes are on the ssRNA of the Avian leukosis?

A

3 genes

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12
Q

True or false. The Avian leukosis does not possess an oncogene, therefore, making it a non acute leukemia virus and it induces leukaemia after a latent period of time.

A

True.

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13
Q

How does the Avian leukosis virus become malignant?

A

Insertion of the DNA adjacent to a cell’s protooncogene. The insertion results

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14
Q

What are tumor-suppressor genes called?

A

Antioncogenes

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15
Q

What happens if these genes are altered or removed?

A

A mutation occurs.

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16
Q

True or false. Oncogenic DNA viruses dont exist.

A

False, they do exist.

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17
Q

What types of viruses have been strongly linked to human cancers?

A

Herpesviruses, papillomaviruses and hep B

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18
Q

How are do these viruses become malignant?

A

The gene product produces malignancies by ending with and inactivating timor-suppressor gene products.

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19
Q

When speaking of multiplication of animal viruses, the attachment and absorption is describe as what?

A

The cell contains specific receptors on its surface. Those receptors are recognized by attachment sites on the virus such as glycoprotein spikes.

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20
Q

During the penetration division- explain the envelope fusion.

A

The envelope contacts the cell membrane. There is a fusion of the two membranes and the nucleocapsid is released into the cytoplasm.

21
Q

Explain a similar process for naked viruses.

A

The virus is engulfed by the cell like phagocytosis and the nucleocapsid is released into the cytoplasm.

22
Q

Explain the uncoating process.

A

It’s the removal of the capsid by the activity of certain enzymes. This exposes the viral nucleic acid. This occurs in the nucleus for the herpesviruses.

23
Q

True or false. The viral nucleic acid is replicated so that the numerous copies are produces during the replication process.

24
Q

Explain how the capsid proteins are of use during the replication process.

A

The viral nucleic acid through the mRNA, directs the synthesis of certain proteins. Some of these are the capsid proteins.

25
Where does most of the assembly take place in the viruses.
This process takes place in the cytoplasm for most viruses and in the nucleus for some.
26
Explain the process of assembly.
Copies of the nucleic acid associated with incomplete capsids and nucleocapsids are formed.
27
True or false. Viruses are the tiniest microorganism.
True
28
Explain what the following statement means. Viruses are obligate intracellular parasites.
Viruses can only grow inside the cell of an organism.
29
True or false. Viruses are structurally complexe.
False. Viruses are structurally simple.
30
What consists of a virion? Name the three. Define virion.
A virion is a complete virus- which means that is consists of a genetic material such as DNA or RNA, the protein coat called the capsid and a membranous envelope.
31
What is a capsid?
A protein coat
32
True or false. The membranous envelope found is found in all viruses?
False. They are found in some viruses but not all.
33
Explain the replication process of the virus cell.
A virus cell will not grow then divide. Rather, they multiply inside the cell by making copies of their individual parts and then assembling them.
34
True or false. The invasion of a single virus cell can result in the formation of hundred of viruses and can infect other cells.
True.
35
Name the three types of viruses cells.
Animal viruses Plant viruses Bacterial viruses
36
Give a synonym for bacterial viruses.
Bacteriophages or phages.
37
Define viroids
are the smallest infectious pathogens known. They are solely composed of a short strand of circular, single-stranded RNA without protein coat.
38
Define prions
Prions, so-called because they are proteinaceous, are infectious particles, smaller than viruses, that contain no nucleic acids (neither DNA nor RNA).
39
Define a icosahedral virus.
This type of virus has a icosahedral capsid surrounding the nucleic acid core. It has 20 triangular faces and 12 corners.
40
Describe the helical virus
They are rod shaped as the nucleic acid core is surrounded by a cylindrical capsid in the form of a helix.
41
True or false. The icosahedral viruses and the helical viruses can't be enveloped. Elaborate.
False. They both can be enveloped as the nucleocapsid is surrounded by a lipid membrane.
42
True or false. The helical viruses have their nucleocapsids folded within the envelope due to the viruse's spherical shape.
True
43
True or False. A virus can have a DNA or RNA which can be a single strand (ss) or double stand (ds).
True
44
Explain where the proteins are bound by in helical virions.
End to end to forma ribbon
45
Explain what the capsomers consists of for the icosahedral virions.
They consist of a number of proteins.
46
Define what envelopes are.
They are the bacterial cell membrane. They are a lipid bilayer with an interspersed protein.
47
Name the two types of proteins when referring to envelopes.
Glycoproteins and matrix proteins.
48
What do glycoproteins resemble under the electron microscopy.
Like spikes on the surface of the virion.
49
True or false. Disinfectants can dissolve the envelope, such as a esther.
False. Disinfectants can dissolve the envelope such as an ether.

Medical Microbiology 1-15 (15 decks)

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