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A-LEVEL BIOLOGY > VIRUSES > Flashcards

VIRUSES Flashcards

1
Q

What are viruses? ()

A

Are disease causing agents, which lack a metabolism of their own so depends on the metabolism of the cells they infect

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2
Q

What is the structure of a virus? (2)

A

Have a core nuclei acid around it which is a protein coat called a capsid, some have an additional external envelope of membrane made of lipids and proteins for example the human immunodeficiency virus

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3
Q

Where do antivirals work where they have been developed? ( 1)

A

Where antivirals have been developed, they musi work by inhabiting viral replication by the chostcells

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4
Q

How do antivirus work where they have not been developed? (1)

A

’ Where anti virals have not been developed disease control must rely on preventing the spread of the virus.

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5
Q

How do we classify viruses?

A

Classifying relys on features such as: - the nature and method of copying the nuclei acid cure
- the nature of their capsid
- their shape
- the organisms they infect

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6
Q

What are 4 types of virus? (4)

A
  • ( lambda )bacteriophage
    -tobacco mosaic virus
    -Ebola virus
  • human immunodeficiency virus
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7
Q

What host organism does the (lambda) bacteriophage infect? (1)

A

Usually bacterium escherichia coli

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8
Q

What is the structure of a (lambda) bacteriophage virus? (2)

A

Has a head, tail and tail fibre.

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9
Q

What is the nature of the nuclei acid core in a (lambda) bacteriophage? (1)

A

Is double stranded DNA.

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10
Q

What is the copying of the nucleic core in a (lambda) bacteriophage? (1)

A

Is double stranded DNA transcribed to mRNA.

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11
Q

What host do the tobacco mosaic virus infect? (1)

A

Plants, especially those in the tobacco family.

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12
Q

What is the structure of a tobacco mosaic virus? (1)

A

Has a protein coat (capsid) of polypeptide building blocks arranged in a spiral around the canal containing RNA.

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13
Q

What is the nature of the nucleic acid core of a tobacco mosaic virus? (1)

A

Is a single stranded RNA.

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14
Q

What is the copying of the nucleus acid core in the tobacco mosaic virus? (1)

A

RNA copied directly to form mRNA.

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15
Q

What host does the Ebola virus infect? (1)

A

Humans, especially endothelial cells, liver cells, immune cells and dendritic cells.

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16
Q

What is the structure of the Ebola virus? (2)

A

RNA and outer protein coat.

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17
Q

What is the nature of the nucleuic acid core in a Ebola virus?

A

Is a single stranded RNA.

18
Q

What is the copying of the nucleic acid core in an Ebola virus?

A

RNA copied directly to form mRNA.

19
Q

What host does the human immunodeficiency virus infect? (1)

A

Humans, the helper lymphocytes.

20
Q

What is the structure of the human immunodeficiency virus? (5)

A

Enzymes, protein coat, capsule, glycoprotein and single stranded RNA.

21
Q

What is the nature of the nucleic acid core in the human immunodeficiency virus? (1)

A

Single stranded RNA.

22
Q

What is copying of the nucleic acid core in the human immunodeficiency virus? (1)

A

RNA reverse transcribed into a double stranded DNA which is incorporated into the host cells DNA and later transcribed to form mRNA.

23
Q

What is viral latency? (2)

A

A period in which under the control of specific latency genes, a pathogenic virus remains dorment. During this time the virus, or its nucleic acid is present inside an infected cell but does not control the cells activities.

24
Q

What are the two types of viral latency? (2)

A

-episomal latency

-proviral latency

25
Q

What is episomal latency? (1)

A

The viral nucleic acid remains inactive but free in the cytoplasm or nucleus of the infected cell.

26
Q

What is proviral latency? (1)

A

The viral nucleic acid becomes incorporated into the DNA of the infected host cell. It is now termed a provirus but, as with episomal latency, the viral nucleic acid can be reactivated at any time.

27
Q

What virus is chicken pox caused by? (1)

A

Caused by the virus called varicella zoster.

28
Q

What is the lytic cycle? (2)

A

In which the viral genetic material replicated independently of host DNA. New viruses are released by lysis. Such viruses are said to be virulent (disease causing).

29
Q

What is the lysogenic cycle? (2)

A

In which the viral nucleic acid is incorporated into the host cell genetic material and spread through host-cell reproduction. The viral nucleic acid may remain inactive (latent) for years before it starts to replicate. Such viruses are termed non-virulent.

30
Q

What is the retrovirus cycle? (2)

A

The retrovirus cycle is a special case of the lysogenic cycle.
The RNA is transcribed to DNA by reverse transcriptase in the host-cell. Viruses leave the cell by exocytosis (not lysis). The host cell continues to make viruses and new ones infect other cells.

31
Q

What are the ethical considerations when using a drug that has not been fully trialed? (6)

A

-the severity of the disease.
-the availability of any other treatments.
-the effectiveness of disease control.
-problems with haltering the spread of the disease.
-transparency about the process.
-informed consent and freedom of choice.

32
Q

What is classified in pre-clinical research of drug development? (3)

A

-discovery and early screening of compound.
-large-scale synthesis.
-animal testing.

33
Q

How long does pre-clinical testing last? (1)

A

At least 5 years

34
Q

What is involved in phase one of any trail for drug development? (1)

A

Is assessed on a small number of participants to assess safety.

35
Q

How long does phase 1 usually last, in terms of trials of drug development?(1)

A

1.5 years.

36
Q

What happens within phase 2 of any trial of drug development?(1)

A

Tested on over 10 participants, to study efficacy.

37
Q

How long does phase 2 usually last ,in terms of trials for drug development?(1)

A

2 years.

38
Q

What happens within phase 3 of any trials in drug development? (1)

A

Tested on over 1000 participants, to study safety, efficacy and dosing.

39
Q

How long is phase 3, in terms of trails of drug development? (1)

A

3.5 years.

40
Q

What was the name of the vaccination for Ebola? (1)

A

rVSV-ZEBOV

41
Q

When was the vaccination for Ebola produced? (1)

A

In July 2015

A-LEVEL BIOLOGY (35 decks)

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