Lecture 2: Energy, Transport and Scavenging in Bacteria

Question 1

Bacterial Decision Making

Answer 1

Planktonic Bacteria -> Attachment -> Microcolony -> Mature Biofilm
->Dispersal

Question 2

Ways of Signaling

Answer 2

2nd messengers Cyclic-di-GMP
-> high concentrations lead to biofilm formation
-> low concentrations lead to planktonic lifestyle
Quorum sensing systems
-> sense other bacteria
Environment Signals

Question 3

Bacterial Economy

Answer 3

Manufacturing, Transport, Surveillance, Waste management, Energy Production, Monitoring others, Motility

Currency: ATP

Question 4

Transportation across Cytoplasmic Membrane

Answer 4

Facilitated diffusion i.e. glycerol in E. coli
Ion-coupled transport
Periplasmic-binding protein-dependent-ATP driven
ATP driven without periplasmic binding proteins
Phosphoenolpyruvate : carbohydrate transfer system

Question 5

Ion-coupled transport: Uniport

Answer 5

Only one molecule is moving
Least common method- facilitated diffusion
Cannot move substrate against concentration gradient

Ex) E. coli glycerol uniporter

Question 6

Ion-coupled transport: Symport

Answer 6

Active and energy dependent
Require substrate to have ion partner
Passes through symport protein in same direction

Ex) Lac permease- transporting lactose

Question 7

Ion-coupled transport: Antiport

Answer 7

Substrate and counter ion move in opposite directions

Exchange accumulated compound for excreted one

Question 8

Chemiosmotic Circuit

Answer 8

ATPase use ATP as energy source to create proton gradient

Used as symporter or antiporter

Question 9

Lactose uptake and Metabolism contains

Answer 9

~LacY permease - a symporter
~LacI repressor - regulates activity of operonic promoter and transports & metabolises lactose in cell
~LacZ protein - beta-galastosidase cleaves lactose disaccharide into glucose and galactose

Question 10

PTS System

Answer 10

For sugar uptake

Energy source from phosphoenolpyruvate (PEP)

Question 11

Catabolite Repressor

Answer 11

E.coli prefers glucose
Glucose controls production of cAMP
Production of cAMP repressed by glucose
cAMP controls large number of genes
cAMP important second messenger as it reports metabolic state of cell

Question 12

What does cAMP stand for?

Answer 12

Cyclic adenosine monophosphate

It is a second messenger for intracellular signal induction