7A Pathogens

Question 1

What are pathogens?

Answer 1

Agents that cause disease in it’s hosts

Cellular and non-cellular

Question 2

What are antigens?

Answer 2

Antigens are unique markers that can be recognised by the immune system

Self and non-self

Question 3

What are ‘self’ antigens?

Answer 3

Antigens that the immune system recognises as self

Question 4

What forms do self antigens take?

Answer 4

Major Histocompatibility Complex (MHC)
MHC class I and MHC class II

Question 5

What are MHC class I?

Answer 5

All nucleated cells

All except for red blood cells

Question 6

What are MHC class II?

Answer 6

All specialised cells
- Macrophages
- Dendritic cells
- Neutrophils

These three all have MHC I and MHC II

Question 7

What is the purpose of the MHC II?

Answer 7

MHC II carries pathogen fragments after they are ‘engulfed’

Question 8

What are ‘non-self’ antigens?

Answer 8

Antigens that the immune system reads as ‘foreign’

Question 9

What happens when ‘non self’ antigens are detected?

Answer 9

If a non self antigen is recognised, the immune system will activate and attempt to eliminate it

Question 10

What are CELLULAR pathogens?

Answer 10

Undergo cellular processes
Can reproduce on their own
- Examples; Bacteria, fungi, worms

Question 11

Briefly describe bacteria

Answer 11

• Prokaryotic, unicellular organisms
• Considered Earth’s first life form
• Most abundant and diverse

Question 12

Briefly describe Fungi

Answer 12

Group of Eukaryotic organisms that include yeasts, moulds, mushrooms, etc.
Can be complex or simple

Question 13

Briefly describe Protozoan

Answer 13

Unicellular, eukaryotic organisms that belong to the protist kingdom

Question 14

Briefly describe Worms

Answer 14

Multicellular invertebrate parasites. Can vary in sizes

Question 15

What are NON-CELLULAR pathogens?

Answer 15

Not made of cells
Cannot reproduce on their own- need a host cell
Do not undergo cellular processes
- Ex. Viruses and Prions

Question 16

What are viruses?

Answer 16

Nucleic acid enclosed in protein coat

Question 17

What are Prions?

Answer 17

Abnormally folded protein

Question 18

What happens when the immune system recognises ‘self’ antigens as ‘non-self’?

Answer 18

The immune system will attack ‘self’ cells, this is called an autoimmune disease.

eg. allergies, lupus, diabetes t1, alopecia

Question 19

How do non-cellular pathogens reproduce?

Answer 19

They inject their own genetic material into the genome of the host

Question 20

Where can antigens be found?

Answer 20

• As a whole molecule (toxics)
• On external surface (pathogens)