lecture 31 - viruses

Question 1

Are viruses cellular or acellular organisms?

Answer 1

Acellular

Question 2

Why can’t viruses survive without a host?

Answer 2

They have no metabolic abilities of their own and rely on the bio synthetic machinery of infected cells to multiply

Question 3

What is an obligate intracellular parasite?

Answer 3

An organism, such as a virus, that rely on a suitable host to complete their life cycle.

Question 4

What are the 2 essential components of a virus?

Answer 4

Genetic material, capsid

Question 5

What is a feature of viruses that only certain types have?

Answer 5

An envelope of lipids that surrounds the protein coat/capsid

Question 6

What is a viral capsid?

Answer 6

A protein coat that surrounds, and protects the genetic material of, a virus.

Question 7

What are viral capsids composed of?

Answer 7

Multiple units of protein building blocks called. capsomers that form a precise pattern around the virus’s nucleic acid.

Question 8

What are 3 types of capsid symmetry?

Answer 8

Helical, icosahedral, complex

Question 9

What is the structure of a helical virus?

Answer 9

Capsomeres coil around the nucleic acid into a tightly bound helix that resembles a tube.

Question 10

What is the structure of an icosahedral virus?

Answer 10

The capsid is an icosahedral shape - a 20 faced polygon made up of equilateral triangles

Question 11

What is the structure of a complex virus?

Answer 11

Contains components with different symmetries - e.g. an icosahedral head with helical tails.

Question 12

How is the viral genome stored?

Answer 12

Nucleic acid - DNA or RNA - contained within the viral capsid

Question 13

Do viruses have DNA or RNA?

Answer 13

Both or either

Question 14

What are the possible structures of the DNA and RNA found in viruses?

Answer 14

Linear, circular, segmented

Question 15

Is DNA and RNA double or single stranded in viruses?

Answer 15

Both ds and ss RNA and DNA are found in viruses.

Question 16

What type of virus infects a host via the lytic cycle?

Answer 16

Bacteriophages

Question 17

What are bacteriophages?

Answer 17

Viruses that infect and then replicate inside bacteria.

Question 18

What is the name of the process in which bacteriophages infect bacteria?

Answer 18

The lytic cycle

Question 19

What are 6 phases off the lytic cycle?

Answer 19

Attach, Penetrate, Uncoat, Genome replication & gene expression, Assembly, Release

Question 20

What occurs during the attachment stage of the lytic cycle?

Answer 20

Phage attaches to the surface of a bacterial cell using its tail fibres

Question 21

What occurs during the penetration stage of the lytic cycle?

Answer 21

Viral DNA is injected into the bacterial cell

Question 22

What occurs during the uncoating stage of the lytic cycle?

Answer 22

The virus phage sheds its capsid, leaving the viral genome exposed

Question 23

What occurs during the gene replication & expression stage of the lytic cycle?

Answer 23

DNA/RNA is replicated, transcripted and translated, and phage proteins/components are made.

Question 24

What occurs during the assembly stage of the lytic cycle?

Answer 24

Several new phage particles are assembled from the phage components manufactured during gene expression.

Question 25

What occurs during the release stage of the lytic cycle?

Answer 25

The bacterial cell lyses/ruptures, releasing the newly made bacteriophages.

Question 26

What is the structure of a SARS-CoV-2 virus?

Answer 26

An enveloped virus, with linear non-segment ssRNA

Question 27

What type of nucleic acid does the SARS-CoV-2 virus have?

Answer 27

single stranded RNA

Question 28

What is the function of the spike on a SARS-CoV-2 virus?

Answer 28

Cell entry and attachment.

Question 29

What part of a SARS-CoV-2 virus is targeted by vaccines?

Answer 29

The spike - to neutralise immunity

Question 30

How do spike viruses bind to the surface of cells?

Answer 30

Receptor Binding Domain (RBD) on spike binds to an ACE2 receptor protein on the cell surface

Question 31

What part of a virus spike protein binds with the cell surface of target cells?

Answer 31

Receptor binding domain (RBD)

Question 32

What part of a cell surface will spike proteins bind to in order for a virus to infect the cell?

Answer 32

ACE2 receptor

Question 33

Where do SARS-CoV-2 viruses replicate?

Answer 33

In the cytoplasm of host cells that they infect

Question 34

What is HIV?

Answer 34

A virus - Human Immunodeficiency Virus

Question 35

What disease does HIV cause?

Answer 35

AIDS - Acquired Immunodeficiency Syndrome

Question 36

What is the structure of the genetic material of an HIV virus?

Answer 36

ssRNA

Question 37

What is a provirus?

Answer 37

A component of a viral DNA/RNA that has been converted to dsDNA by reverse transcriptase and that is incorporated into the nucleus of a host cell for expression.

Question 38

What enzyme is used to incorporate the genetic material of a virus into the host genome?

Answer 38

Viral integrase

Question 39

What is a prophage?

Answer 39

The genetic material of a bacteriophage that is incorporated into a bacterial genome and then produce proteins if transcripted and translated.

Question 40

Are viruses visible under a light microscope?

Answer 40

No - only visible with an electron microscope