Virus (H&D 003)

Question 1

What is the definition of a virus

Answer 1

Viruses are obligate intercellular parasites, a poison or venom that is able to self-replicate via resources from their host cell

Question 2

What are the three general characteristics of a virus

Answer 2

Size, structure and metabolism and host range

Question 3

What is the size of a virus

Answer 3

Very small

Question 4

What is the metabolism and structure of a virus

Answer 4

Acellular, do not carry any MRS GREN processes, lack enzymes and produces waste products

Question 5

What is the host range of a virus

Answer 5

The range of a virus’s infection, dependent on the receptors of the host cell and the virus

Question 6

What are the four structures of the virus

Answer 6

Genome, capsid, envelope and spikes

Question 7

What is the function of the genome

Answer 7

A genome is a nucleic acid, it can either be RNA or DNA

Question 8

What is the function of the capsid

Answer 8

A protective coat of the virus in which is made of protein, consists of tiny sub-units called capsomeres

Question 9

What is the function of the envelope

Answer 9

A membrane, some viruses have this

Question 10

What is the function of spikes

Answer 10

Enables the virus to attach itself to the surface receptors of the host cell

Question 11

What effects does it have on a host cell when affected by a virus

Answer 11

Cell death (lysis), viral particles build up in the host cell disrupting function, viruses are released in short bursts (persistent infection) or nothing happens for a period of time until a certain stimulus is triggered to initiate the lytic cycle (latent infection)

Question 12

What is the definition of latency

Answer 12

The ability of a pathogenic virus to lie dormant within a cell

Question 13

What is the definition of bacteriophage

Answer 13

A virus that specifically infects bacteria

Question 14

What is the definition of lytic cycle

Answer 14

The normal process of viral reproduction involving penetration of the cell membrane, nucleic acid synthesis, and the lysis of the host cell

Question 15

What is the definition of the lysogenic cycle

Answer 15

A form of viral reproduction involving the fusion of the nucleic acid of a bacteriophage with that of a host, followed by proliferation of the resulting prophage

Question 16

Why do viruses replicate

Answer 16

In order to create new infection virions to infect other cells of the body.

Question 17

What are the four stages in the lytic cycle

Answer 17

Attachment, uncoating, component biosynthesis, Assembly and release

Question 18

What occurs in attachment in the lytic cycle

Answer 18

The spikes of the virus attach to the surface receptors of the host cell (Endocytosis)

Question 19

What occurs in uncoating of the lytic cycle

Answer 19

The capsid is removed in which nucleic acids are released

Question 20

What occurs in component biosynthesis in the lytic cycle

Answer 20

Genome is replicated and translated to make new viral components, enveloped viruses are prepared in the cell membrane ready to be released

Question 21

What occurs in assembly and release in the lytic cycle

Answer 21

Viral components are fused together to form a virus, naked virus lyse the cell to be released whereas enveloped viruses push through the prepared cell membrane

Question 22

What is the difference between lytic and lysogenic viral infections

Answer 22

Lysogenic viral infections have an extra step called integration

Question 23

What is the integration in lysogenic viral infections

Answer 23

The viral infection is integrated with the host genome for a long period of time (latent infection)