Microbiology Unit Test Review

Question 1

What is a virus?

Answer 1

A non-cellular particle made of genetic material (DNA/RNA) which can invade living cells.

Question 2

Examples of viruses:

Answer 2

Covid-19, Influenza, HIV, Measles, Polio, Mumps, Cold Sores, Ebola, etc etc

Question 3

What is R0? Which virus has the greatest #?

Answer 3

R0 is the basic reproduction rate/number.
(Measles?) has the greatest number.

Question 4

What is a virus’s ultimate goal? Why is quick host killing bad?

Answer 4

The ultimate goal is to replicate and spread.
Quick host killing is bad because it lessens the virus’ chance of spreading.

Question 5

What is the hypothesis scientists have about the origin of the virus?

Answer 5

They developed from cellular ancestors and became used to a parasitic way of life. NS favored the loss of cellular parts.

Question 6

Are viruses alive? Why or why not? State the arguments for both sides.

Answer 6

NO, viruses are NOT alive.
Arguments for NOT ALIVE:
- they are not made up of cells (building block of life)
- relies largely on hosts
- cannot keep themselves stable by homeostasis
- cannot move (not motile)

Arguments for ALIVE:
- can reproduce
- has genetic material

Question 7

Capsid (function + structure)

Answer 7

holds genetic material, made of protein.

Question 8

Nuclear acid core (function + structure)

Answer 8

genetic material (DNA/RNA); double helix/half of double helix

Question 9

Spikes/glycoprotein (function + structure)

Answer 9

unlocks host cells (analogy: key and cabinet lock where the glycoproteins are the keys)

Question 10

Tail fiber (function + structure)

Answer 10

receptor sites used to recognize specific cells to invade; leads to viral specificity.

Question 11

Base plate (function + structure)

Answer 11

contains enzymes to cut a hole in the cell wall in order for the genetic material to be “sent” into the host

Question 12

Envelope (function + structure)

Answer 12

extra protein covering (armour). makes virus less susceptible to changes in temp., acidity and disinfectants

Question 13

How are viruses categorized?

Answer 13

1. whether it has dna/rna
2. strain (e.g. “this year’s flu strain is pretty mild”)

Question 14

Define viral specificity

Answer 14

?

Question 15

difference between endemic, epidemic and pandemic?

Answer 15

endemic: present in a community at all times; moderate rate.

epidemic: sudden outbreak affecting a certain area; more cases than expected

pandemic: sudden outbreak affecting large regions of the world/worldwide.

Question 16

what is the difference between antigen and pathogen?

Answer 16

antigen: substances that can trigger an immune response
pathogen: micro-organisms that can cause disease

Question 17

what are the four jobs of the activated helper-t cell?

Answer 17

1. divide rapidly
2. activate the cytotoxic t cell
3. makes memory t cells
4. activates the b cells (specific to the virus)

Question 18

explain cell-mediated immunity.

Answer 18

1. macrophage eats virus by endocytosis
2. virus is “digested” and viral antigens are displayed by the macrophage
3. helper t-cell is activated.
4. helper t-cell divides rapidly
5. activates the cytotoxic t cell
6. makes memory t cells
7. activates (very specific) b-cells

Question 19

explain humoral immunity

Answer 19

1. antigen binds to antibodies
2. activated b cells grow and divide rapidly
3. b cells produce plasma cells and memory b cells
4. plasma cells release antibodies that captures antigens and then kills them