Thermodynamics of Transport Flashcards
What are the problems for transport in biology?
- Cells surrounded by impermeable membrane
- Compartmentalisation requires specific transport
- Various membranes must maintain concentration gradients
- Need to transport molecules across membranes
What’s the value for ΔG for passive transport?
Less than 0
What is the ΔG for active transport?
greater than 0
If the electrochemical gradient goes one way whilst concentration gradient goes the other way which way is substrate transported?
Depends on the magnitude of membrane potential and concentration gradient
What are channels?
An aqueous pore allowing specific molecules through
What are the differences between channels and transporters?
- Transporters can transport up or down a electrochemical gradient whereas channels can only transport down an electrochemical gradient
- Channels can be gated to control access
What is a secondary transporter?
Coupled transporter which makes use of energy generated in a gradient to transport something else
What do eukaryotic cells usually use to provide energy in secondary transporters?
Na+ gradient
What is a primary transporter?
ATP or redox-driven pump
What modes of transport are coupled transport?
Symporters and antiporters
How can the kinetics of secondary transport been determined?
Measure the rate of a transport reaction as a function of substrate concentration
How is rate of transport measured?
How many moles of substrate are transported per second
What is the kinetics of substrate movement through transporters similar to?
Michaelis-Menten
What can the kinetics of substrate movement be used to determine?
The stoichiometry of co-transported ion
