Chapter 6 - Pathogens

Question 1

Define:

1. Pathogens
2. Asymptomatic carriers
3. Contagious
4. Vector
5. Antigen
6. Self-antigen
7. No-self antigen
8. Allergen

Answer 1

1. Pathogen = infectious agent that causes disease to another organism.
2. A symptomatic carriers = show no symptoms, but can spread the disease.
3. Contagious = very easily spread, passed by contact.
4. Vector = an agent that transfers a pathogen from one organism to another.
5. Antigen = any molecules that initiate an immune response.
6. Self-antigen = molecule that belongs in a particular person; would cause an immune response if given to another person.
7. Non-self antigen = molecule/foreign material that doesn’t belong and induces an immune response.
8. Allergen = an antigen that causes an allergic reactions; these cause no harm, but the body overreacts.

Question 2

How pathogens:

1. Cause infections
2. Cause disease

Answer 2

1. Gains entry into human body and multiplies.

2. Body cells or organs are damaged.

Question 3

6 examples of cellular pathogens

Answer 3

1. Bacteria
2. Protozoans
3. Oomycetes - protista, release spores
4. Fungi - send out spores and hyphae
5. Worms - ectoparasitic and endoparasitic
6. Arthropods - insects, ticks and mites

Question 4

Non-cellular pathogens
1. Viruses 
• DNA or RNA (ss or ds) enclosed in?
• released from host cells by?
• enveloped viruses
• naked viruses 
2. Prions

• viruses and prions
• not living organisms
• must have a host to survive

Answer 4

1. Viruses
   • a specific protein coat known as capsid.
   • budding or lysing the cell
   • released from cells in buds, which capture part of the cells plasma membrane.
   • a virus lacking the viral envelope; tend to lyse = host cell explodes and viral particles are released.
2. Prions
   • only proteins
   • found mainly in nerve cells.

Question 5

Self markers/surface molecules on individuals’ cell membranes are products of a group of genes called?

Answer 5

Major histocompatibility complex (MHC)