CSIM 1.34 Bacterial Major Structural Components

Question 1

Define:

1) Microbiota

2) Microbiome

Answer 1

1) The microorganisms of a particular site
2) The combined genetic material of the microorganisms in a particular environment (i.e. an idea of the enzymes and chemicals present)

Question 2

How does the microbiota and microbiome vary between different body parts in healthy individuals?

Answer 2

Microbiota:
• Varies drastically

Microbiome
• Relatively constant

IMG 83

Question 3

Are skin flora mostly gram positive or negative?

Answer 3

Gram positive around head

Gram negative around arms

overall predominantly gram positive

IMG 84

Question 4

What structures are skin microflora mostly associated with?

Answer 4

• Sweat ducts
  
  • Hair follicles

NB: washing wont remove this

Question 5

As you move down the digestive tract, how does concentration of bacteria vary?

Answer 5

Increases (IMG 85)

Question 6

What is Bacteroidetes?

Answer 6

A genus of gram-negative bacteria crucial in the gut which digests cellulose and contains sphingolipids

Question 7

What metabolic processes occur at the plasma membrane of bacteria?

Answer 7

• Respiration

* Uptake of required chemicals

Question 8

What is a bacterial nucleoid

Answer 8

• Localisation of bacterial DNA in the cell

* Made up of a single chromosome

Question 9

What are plasmids?

Answer 9

Small circular pieces of DNA that exist and replicate independently of the chromosome nucleoid, and are horizontally transferred between bacteria

Not required for growth and reproduction, however contains genes which may confer a selective advantage such as drug resistance

Question 10

What are inclusion bodies?

Answer 10

Vesicles that bacteria use to store carbon, fat and phosphates.

Question 11

What is the periplasmic space?

What does this contain?

Answer 11

The space between the cell membrane and the cell wall

Contains hydrolytic enzymes and binding proteins for nutrient processing and uptake

Question 12

What are the functions of bacterial cell walls?

Answer 12

• Protection from osmotic pressure
  
  • Adhesions to surfaces
  • Protection from toxic substances
  • Protection from bacteriophage infection

Question 13

What is a Mycoplasmas?

Answer 13

A genus of bacteria with no cell wall around their cell membrane

Question 14

What are capsules/slime layers and their functions?

Answer 14

Polysaccharides outside the cell wall which 
  •  Prevent dehydration
  •  Increase adhesion (sticky)
  •  Resist phagocytosis
  •  Hides cell from immune recognition

Capsules
• Fixed

Slime layer
• More lipid-based
• Disorganised

Question 15

What are fimbriae and Pili? What are the functions of this?

Answer 15

Hairs on the side of bacteria. Involved in:
• Bacterial mating (IMG 86)
• Adhesion

Fimbriae
• Short, thin, hairlike, protein appendages, 1000 per cell

Question 16

What are endospores?

Answer 16

In harsh conditions a bacteria can be shut down, it can build a solid structure around itself and become dormant until conditions becomes more favourable