9. Host-bacterial interactions.

Question 1

Colonisation factors of bacteria

Answer 1

1. Entry via movement
2. Adhere to skin or mucosa via capsule/fimbriae formation
3. Invade through epithelium (if pathogenic)
4. Growth and colonisation

Question 2

Main bacterial abilities

Answer 2

Mobility and adherance.
When bacteria finds niche, no transfusion time.
Doesn’t stick to only mucosal surfaces (particles, human cells and bacteria)
Often grows as communities (Biofilm)

Question 3

Biofilms - Definition

Answer 3

Community lifestyle of microorganisms

Question 4

Biofilms, result of…

Answer 4

Adhesion

Question 5

Biofilms - Positives

Answer 5

Mature biofilms contain single or multiple species
Not restricted to host surfaces
Provide ideal environment for extra chromosome

Question 6

Biofilms - Major issues

Answer 6

Medical devices.

Catheters

Question 7

Biofilms - Protection

Answer 7

Bacteria in biofilm protected from immune reponse and environment.

Question 8

Biofilms - Chemical gradient

Answer 8

Formed in biofilms allows existence in range of states

Question 9

Bacterial capsules - Definition

Answer 9

Polymer of repeating sugar units

Loosely encases bacterial or releases into environment

Question 10

Bacterial capsules - Function

Answer 10

Hides cell from immune system
Causes tissue damage in plants
Forms biofilms in phloem and xylem

Question 11

Bacterial capsules - Uses

Answer 11

Used in industry as xanthan gum alginate

Question 12

Fimbrial plius: Chaperone usher process

Answer 12

1. Secretion (via sec machine)
2. Chaperone (periplasmic space)
3. Uher (outer membrane)
4. Plius (Fimbriae/FimA)
5. Adhesion (FimH, lectin like proteins binds sugars)

Question 13

Endotoxins

Answer 13

Many are plasmid encoded on bacteriophage.
Cytolytic toxins.
AB toxins.
Superantigens.
Enterotoxins.
Neurotoxins.

Question 14

Cytolytic tocins

Answer 14

Leads to cell lysis

Question 15

AB toxins

Answer 15

A - Inhibits cell processes and damages

B - Bids to specific cell receptors. Facilitates A uptake

Question 16

Superantigens

Answer 16

Overstimulate immune system

Question 17

Enterotoxins

Answer 17

Acts on small intestine

Question 18

Neurotoxins

Answer 18

AB toxins acting on nerve cells

Question 19

Biofilms - Formation

Answer 19

1. Adsorption
2. Irreversible attachment
3. Growth and division
4. Mature macrocolony
5. Dispersion

Question 20

Protein secretion

Answer 20

Gram positive - One step process
Gram negative - Two step process

General pathways across inner membrane:

1. Secretion/Sec (Unfolded protein)
2. Twin argenine translocation/TAT (Folded protein)

Secretion in gram negative bacteria:

1. Inner membrane (Sec)
2. Outer membrane (specific system)

Question 21

Pathogenicity

Answer 21

Qualitative.

Degree to which they cause disease

Question 22

Virulence

Answer 22

Quantitative.

Structures making something pathogenic

Question 23

Pathogenicity factor

Answer 23

Essential for pathogenesis

Question 24

Virulence factor

Answer 24

Factors involved in pathogenesis

Question 25

Pathogenicity factor evolution

Answer 25

Horizontal gene transfer
Often assisted by phages
Retained if provide selective advantage