Mer Scott
Quiz by , created more than 1 year ago

Objectives: describe the basic structural characteristics of viruses, compare the lytic and lysogenic replication cycles of bacteriophages, outline the replication cycles of mammalian cell viruses(naked and enveloped), describe the term viral latency in relation to the replication of bacterial and mammalian viruses.

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Mer Scott
Created by Mer Scott over 7 years ago
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L5 Structure and Function of viruses

Question 1 of 13

1

Which statement about viruses is NOT correct?

Select one of the following:

  • Viruses can multiply only by using a dividing host cell's machinery.

  • Viruses are ubiquitous.

  • Virus particles are called virions.

  • There is estimated to be around 2000 viruses which affect humans.

Explanation

Question 2 of 13

1

Which statements BEST describes viruses?

Select one or more of the following:

  • Viruses are a diverse group of acellular or 'sub-cellular' particles with no metabolic activity of their own, which rely on the biomachinery of their hosts to reproduce.

  • Viruses are very small non-living cells which hijack living cells in order to reproduce copies of themselves.

  • Viruses are ubiquitous 'sub-cellular' particles which rely on their hosts to reproduce.

Explanation

Question 3 of 13

1

The independent particles of viruses are called , whose genetic material can be or double stranded DNA or . This is protected by a protein coat known as a .
Viruses with only a capsid are 'naked'. Viruses with an around this protein coat are 'enveloped'. This envelope of lipids can sometimes have .

Drag and drop to complete the text.

    virions
    single
    RNA
    capsid
    envelope of lipids
    glycoprotein spikes

Explanation

Question 4 of 13

1

Select the statements about viral capsids which are CORRECT.

Select one or more of the following:

  • Viral capsids are always symmetrical and made of repetitive structures.

  • Capsomers and protomers are the sub-units of capsids.

  • Protomers are made up of capsomers.

  • Capsids can be helical, icosahedral, or complex in shape.

Explanation

Question 5 of 13

1

Which order of the steps of the viral life cycle is CORRECT?

Select one of the following:

  • entry, attachment, synthesis, assembly, release

  • attachment, entry, assembly, synthesis, release

  • attachment, entry, synthesis, assembly, release

Explanation

Question 6 of 13

1

Lytic=virulent and lysogenic=latent.

Select one of the following:

  • True
  • False

Explanation

Question 7 of 13

1

Bacteriophages are the virions which have a capsid specialised to infect bacterial cells.

Select one of the following:

  • True
  • False

Explanation

Question 8 of 13

1

Which statement about bacteriophage replication types is INCORRECT?

Select one of the following:

  • Lysogenic cycles are temperate e.g. can kill the cell or live within it.

  • The lytic cycle ends in cell lysing.

  • The lytic cycle releases 10-20 virions.

  • Lytic and lysogenic cells both inject their DNA into the host cell in order to reproduce.

Explanation

Question 9 of 13

1

Which statement BEST describes a prophage?

Select one or more of the following:

  • A prophage is the phage genome of the bacteriophage, either integrated with the DNA of the Lysogen (bacterium) or floating free in its cytoplasm, able to produce a lytic phage.

  • A prophage is the inserted DNA from the bacteriophage which lives inside the host cell, known as the Lysogen.

  • The prophage lives in the Lysogen and can become a lytic phage.

Explanation

Question 10 of 13

1

Which statement is true?

Select one of the following:

  • Lytic insertion is followed by immediate degradation of host DNA while the lysogenic genome only becomes virulent when induction (environmental stress, UV irradiation) occurs.

  • Lytic insertion does not harm the host DNA until the final stage of the lytic cycle.

Explanation

Question 11 of 13

1

Retroviruses must use the host cell's machinery, and their own enzyme Reverse Transcriptase, to make DNA from their RNA. An example is HIV.

Select one of the following:

  • True
  • False

Explanation

Question 12 of 13

1

Naked viruses enter the cell via receptors (endocytosis). Enveloped viruses fuse their viral envelope with the host's membrane.

Select one of the following:

  • True
  • False

Explanation

Question 13 of 13

1

The provirus (DNA of enveloped virus in host genome) is virulent.

Select one of the following:

  • True
  • False

Explanation

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