Infection L1

Question 1

State the 7 groups of microoganisms

Answer 1

1. Bacteria
2. Archae
3. Protozoa
4. Algae
5. Fungi
6. Viruses
7. Multicellular animal paraistes (helminths)

Question 2

Phylogeny

Answer 2

1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species

Question 3

State an example of a prokaryote

Answer 3

Bacteria

Question 4

State examples of bacteria

Answer 4

Spheres - Cocci
Rods - Bacilli
Spirals

Question 5

State the definition of infection

Answer 5

Growth of microorganism in host
NOT SYNONYMOUS WITH DISEASE (host does not have to experience disease as a result of infection)

Question 6

State the definition of Pathogen

Answer 6

An organism that causes damage to the host

Question 7

State the 3 types of pathogens

Answer 7

1. Opportunistic - does not cause disease in healthy individual but can cause illness when host’s immunse system is weakened
2. Primary - can cause disease in healthy host - does not require weakened immune system to initiate an infection
3. Zoonotic E.Coli 0157- Zoonotic - transmitted from animals to humans. examples include foodborne illnesses from contaminated water

Question 8

State the meaning of pathogenicity

Answer 8

Ability of microoganism to cause disease

Question 9

State the meaning of virulence

Answer 9

The degree of pathogeniciy

Question 10

State the meaning of parasite

Answer 10

An organism that lives on a host (host is secondary organism)
Causes harm to host, gets food from host

Question 11

Microbes and Humans

Answer 11

1. Most microboes are NEVER PATHOGENIC
2. Many microbes are POTENTIALLY PATHOGENIC
   (survival, growth and propogation)
3. Very few microbes are ALWAYS PATHOGENIC

Question 12

What factors affect virulence and pathogenicity of the genome ?

Answer 12

Composition of genome

Environment (for example, pathogen’s virulence is reduced in cultured conditions)

Question 13

Explain how different virulence factors help bacteria

Answer 13

Virulence factors are specific traits possessed by pathogens to enhance abilty to cause disease in host.

1. Attatchment (via adhesins): Adhesins are specialised molecules on surface of bacteria, allow them to attach themselves to host cells. First step in initiating infection.
2. Colonizanion (and enzymes): After attatchment, bacteria produce enztmes which break down host tissues / ECM, allows them to spread + multiply
3. Invasiveness: Bacteria’s ability to penetrate deeper into host
4. Toxins (& enzymes): produced by bacteria to harm host cells. Enzymes do same
5. Inhibition of phagocytosis: Bacteria evade immune response of host

DIAGRAM L1

Question 14

State the definition of toxins

Answer 14

Chemicals produced by pathogens which arm tissues and trigger host immunse response that causes damage

“substance that contributes to pathogenicity”

Question 15

Toxigenicity

Answer 15

Ability to produce toxin

Question 16

Toxemia

Answer 16

Presence of toxin in host’s blood

Question 17

Toxoid

Answer 17

Inactivated toxin used in vaccine

Question 18

Antitoxin

Answer 18

Antibodies against a specific toxin

Question 19

State the two types of toxins

Answer 19

1. Exotoxins
2. Endotoxins

Diagram L1

Question 20

Endotoxins

Answer 20

1. Produced by gram-negative bacteria
2. Found in outer membrane of bacetria cell, released when bacteria cell is damaged / lysed (broken open)
3. Harmfull effects on host organism incl inflammation + immune response

Made of Lipid A. Lipid A is part of outer membrane of gram negative bacteria

Question 21

State 3 examples of Gram-Negative Bacteria

Answer 21

1. Salmonella
2. Pseudomonas
3. E. coli

Have more complex cell wall structure that has an outer membrane

Question 22

Exotoxins

Answer 22

1. Produced by BOTH Gram-positive and Gram-negative bacteria
2. All major gram-psoitives produce exotoxin

Question 23

Describe how exotoxins cause damage

Answer 23

1. Signalling at host membranes (type I exotoxins)
2. Damaging membranes (Type II exotoxins)
3. Entering target cells + directly altering function (type III exotoxins)

Question 24

State the 3 CLASSES of toxins

Answer 24

Neurotoxins
(specifically target nervous system)

Enterotoxins
(affect lining of GI tract)

Superantigens
(induce intense immune response)