Viruses

Question 1

Virus

Answer 1

A virus is an infectious agent that cannot reproduce by itself

Question 2

Why is a virus not considered a cell and not considered to be alive

Answer 2

Viruses are functionally dependent on host cells

Viruses are acellular
because they do not consist of cells
➔
Viruses have no cytoplasm,
organelles, cell
membranes

Question 3

Structure of a virus

Answer 3

A protective protein coat,
or capsid

➔ Genetic material ( DNA or RNA ) inside of the capsid

➔ Some viruses have another layer covering their capsid known as a viral envelope

Question 4

Bacteriophage =

Answer 4

virus that infects bacteria

× Phages DO NOT enter
the cell

× Inject their DNA only

× Often used in
biotechnology

Question 5

How are viruses classified

Answer 5

They are classified on the size and shape of the capsid

Question 6

Viral reproduction

Answer 6

Viruses require a host cell to reproduce

Question 7

Lytic cycle

Answer 7

1. Attachment - virus attaches to surface of host cell
2. Penetration - The viral DNA/RNA enters the host cell
3. (Bio) Synthesis - viral proteins components are made by host cell
4. Assembly - virus assembled
5. Lysis (Breaks open) - The Cell lyses, releasing the newly made viruses

Question 8

CHECK Lysogenic Cycle

Answer 8

Virus remains dormant
Virus does not kill cell outright

Question 9

Can antibiotics be used against viruses? Why or why not

Answer 9

Unlike diseases caused by bacteria, viral diseases cannot be treated by antibiotics as viruses have no cellular machinery

■ Two ways to fight viral infections:
■ White blood cells act as a defense and destroy viruses that have
invaded your body
■ Use a vaccine to prevent viral diseases

■ Vaccine
– A liquid preparation of dead Or weakened virus particles that stimulate and prepare your body’s immune system to fight the virus if it ever invades your body