C.6 Introduction to Viruses

Question 1

What are viruses?

Answer 1

Small, subcellular organism with an obligate parasitic intracellular lifestyle

Question 2

What are viruses composed of ?

Answer 2

1. Proteins
2. Nucleic acid
3. Lipids

Question 3

What are the sizes of viruses ?

Answer 3

20-100nm

Question 4

Where are viruses found ?

Answer 4

Ubiquitous

Found everywhere

Question 5

Who can host viruses ?

Answer 5

Every living organism can host viruses

Bacteria, fungi, animals, plants

Question 6

Can viruses host other viruses?

Answer 6

Yes. For example giant mamavirus can be infected with sputnik virus

Question 7

How many viruses can ppl be infected with (At any point)

Answer 7

At least 2 different viruses

Question 8

True or false?

When infected with a virus, it will always persist in cells?

Answer 8

True, once infected you will always carry low levels of the virus in cells

Therefore viral genome will be part of the host. When DNA replicates, so does the viral DNA/RNA. This explains transmission to future generations

Question 9

What are the properties of viruses ?

Answer 9

1. Viral genomes (DNA or RNA) are packaged into particles, necessary for transmission between hosts
2. The viral genome contains all the information needed for replication within permissive host cell
3. Viral survival ensured by establishing its genome in a host (cell) population
4. All viruses are obligated intracellular parasites- They need the cellular machinery from host cells (Ribosomes, tRNA etc) to replicate

Question 10

How can you classify viruses based on structure and morphology?

Answer 10

1. Naked virus or enveloped virus

2. Shape of the capsid (Protein containing viral DNA or RBA), which is either helical or icosahedral