Chapter 24 (Part 2)

Question 1

Viruses are not considered ‘living’ because

Answer 1

hey possess only a few properties of living organisms.

Question 2

Viruses do not have..

Answer 2

a cell membrane or cellular organelles and they can not replicate outside of host cells

Question 3

viruses hereditary material can be…

Answer 3

DNA or RNA

Question 4

viruses can only infect specific cell types that contain…

Answer 4

receptors that the virus can bind to

Question 5

zoonotic infections

Answer 5

Viruses can sometimes bind to similar receptors in more than
one species

Question 6

Viruses that infect multiple organisms have a higher rate of
mutation, therefore a higher rate of

Answer 6

‘evolution’

Question 7

pandemic

Answer 7

an infectious disease epidemic that has spread across a large region: ie. multiple continents or worldwide.

Question 8

Viruses are how many times smaller than human cells?

Answer 8

100 to 10000 times smaller

Question 9

Helical viruses

Answer 9

have a hollow centre and can be very long

Question 10

Polyhedral viruses

Answer 10

have only protein surrounding them

Question 11

Enveloped viruses

Answer 11

steal membrane from the host to help them bind to new cells

Question 12

Bacteriophages

Answer 12

only infect bacteria, complex structure, inject genetic material into a bacterium (the remainder is discarded.

Question 13

lytic cycle

Answer 13

If a virus kills the infected host

Question 14

lysogenic cycle

Answer 14

If the virus integrates itself into the host genome and remains dormant as the host cell replicates

Question 15

Attachment

Answer 15

Proteins on the virus capsid bind to a specific receptor

Question 16

Infiltration

Answer 16

The host cell takes up the virus

Question 17

Replication

Answer 17

The virus uses host cell organelles, nutrients, and ATP to make new virus particles

Question 18

Assembly

Answer 18

New virus particles form and are released from the host cell, causing lysis and death of the host cell

Question 19

viruses that contain RNA must do what before they replicate within the host cell?

Answer 19

convert RNA to DNA

Question 20

The process of converting RNA to DNA requires the enzyme…

Answer 20

reverse transcriptase

Question 21

Why do RNA viruses mutate more rapidly?

Answer 21

reverse transcriptase enzymes make many mistakes during replication and lack “proofreading” ability
This high mutation → new variants

Question 22

HIV

Answer 22

is an RNA virus that infects specific white blood cells and integrates into the host cell’s genome: (a retrovirus)

Question 23

Since most of these immune cells die by lysis…

Answer 23

Leads to low levels of properly functioning immune cells

Question 24

Decline in immune cell numbers …

Answer 24

Body becomes more susceptible to opportunistic infections

Question 25

If untreated, HIV-infected individuals develop…

Answer 25

AIDS (acquired immunodeficiency syndrome)

Question 26

What cell can be infected by HIV?

Answer 26

Macrophages, dendritic cells, and T cells

Question 27

Coronaviruses

Answer 27

large family of viruses usually causing mild to moderate upper-respiratory tract illnesses like the common cold