L8 - Diversity & Biology Of Bacteria 2

Question 1

Bacterial cytoplasmic structure: plasmids

Answer 1

• circular or lineal extra chromosomal DNAs
• not essential but provides a selective advantage
• capable of autonomous replication

Question 2

Give an example of advantage that the plasmid gave to tuberculosis

Answer 2

Bacteria can survive in macrophages and manipulate the phagocytosis pathway to avoid being killed. It replicates inside macrophages

Question 4

How is antibiotic gene acquired through plasmid

Answer 4

• acquisition of plasmid = resistant to antibiotics
• pillus transfers via conjugation from donor to recipient, transfers the antibiotic resistant gene through plasmid

Question 5

What is the function of the flagella? What is the structure?

Answer 5

Provides motility, proton motive force used for energy

Long helical filament that extends outside teh cell connecting hook to basal body that turns the flagellum

Question 6

What is the flagella made up of and how is it easily recognised by immune system?

Answer 6

Hollow structure formed with single protein (flagellin). Flagellin has H antigen that is highly antigenic (PAMP) and is easily recognised by immune system

Question 7

Helicobacter pylori colonies human stomach and causes acute gastritis and several ureases. How?

Answer 7

• bacteria travels through mucus (function of flagella aids the bacteria to reach the epithelial cells)
• bacterial destroys cells so no mucus is made
• urease → gastric lumen is rich in urea, ureases break down urease which produces ammonia and neutralises pH

Question 8

What are Pili and fimbriae and what is the difference between them?

Answer 8

Protein spikes that extend from the surface. Pili are typically longer than fimbriae
Fimbriae are more abundant per cell than Pili

Question 9

What are the functions of Pili and fimbriae

Answer 9

Adhesion and twitching motility (extension and retraction of Pili)

Question 10

What is the twitching motility?

Answer 10

Pili attach to surface retract and move forwards, diff type of motility to flagella, protein assembles and deassmble to allow bacteria to move

Question 11

What does the Pili allow

Answer 11

Sex pills involved in DNA transfer in conjugation

Question 12

What is the capsule and its function

Answer 12

Slime surrounding cells bound to bacterial cell wall. Barrier to toxic hydrophobic molecules

Question 13

How does streptococcus pneumoniae evolve quickly?

Answer 13

Diff composition of capsule to evolve resistance
- capsule masksthe bacteria from being recognised
- each diff combination of composition of capsule produces different serotype

Question 14

What is natural transformation

Answer 14

Environmental DNA is bound at the surface of competent cells and transported to the cytosolic compartment. acquire DNA from the environment and recombine into the chromosome using transformation field called pili

Question 15

Why is it important to study bacterial metabolism

Answer 15

• identify nutrient requirements for microbial pathogenesis
• understand metabolic networks and its regulations
• understand how bacterial pathogens adapt to different host environments
• identify new drug targets and understand the mechanism of action of drugs

Question 16

What are the nutrient factors that a bacteria needs

Answer 16

Macronutrients (e.g. C, N, phosphorus, potassium sulfur)
Growth factors (vitamins, AA)
Micronutrients (iron, born, zinc, copper)

Question 17

How do bacteria acquire nutrients? 2 types of transports?

Answer 17

Passive and active (energy required)
Passive - simple or facilitated
Active - ion-couple transport, PTC system ABC transport

Question 18

Describe the 2 types of passive transport

Answer 18

Simple diffusion - through membrane
Facilitated diffusion - hydrophilic molecules require channel or carrier

Question 19

Describe the ion-coupled transport

Answer 19

Proton symport
- driven by proton motive force that co-transports in the same direction

Question 20

Describe ABC transport

Answer 20

ABC transporters (ATP binding cassette)
- hydrolysis of ATP drives transport
- specific binding proteins

• 3 main components
  
  • extend and binds to solute (very specific, e.g. maltose will have its own extenal part that binds to maltose)
  • protein channel sitting in membrane
  • transforms ATP to ADP providing energy to open protein channel

Question 21

Describe group translocation

Answer 21

• substrate modified (usually phosphorylation) during transport
• energy provided by PEP passed along chains of enzymes
• modification of teh sugar maintains conc gradient
• phosphate transferred to sugar to cross through protein channel

Question 22

How is transport different in gram negative bacteria?

Answer 22

Double membrane so it have diff protein channels and modes of transport on each

Question 23

How is glucose transported in bacteria

Answer 23

• glucose transported through multiple transport systems
• system is redundant bc glucose is very needed

Question 24

What energy source is used by bacteria in their first log phase vs second log pages

Answer 24

1. Glucose (preferred)
2. Other energy source

Question 25

When e.coli infects the urinary tract, what kind of metabolism does it have to adopt

Answer 25

- bacteria needs to switch from glucose to peptides - requires special protein that uptakes peptide - peptide degradated to produce glucose - gluconeogenesis (amino acids → glucose), very expensive Gluconeogenesis & TCA cycle

Question 26

How does listeria monocytogenes get its nutrients

Answer 26

Uptake of glucose 6 phosphate through utilisation of host sugar phosphates via specific transporter activated in the host to promote rapid intracellular growth