Lecture 4 Flashcards
Discuss the 3 membrane transport types.
Nature of transported substances: transport of inorganic ions and small water soluble organic molecules.
Vesicles transport for macromolecules
Based on energy consumption;
Passive or active transport
Based on the site where substances pass thru membrane;
Transport through lipid double layer or transport through transporter proteins
Explain passive transport.
Down or across conc gradient?
What are the two types of diffusion?
DOWN concentration gradient.
Simple diffisuion or facilitated diffusion through channels and passive carriers.
Active transport
Input of metabolic energy by atp hydrolysis or indirectly by the electrochemical gradient of ions.
Mediated by carriers that harvest metabolic energy to pump solute. AGAINST ELECTROCHEMICAL GRWDIEMT
Talk about simple diffusion
What does it depend on?
When will it be fastest?
Depends on the permeability of the lipid bilayer to different molecules.
Smaller, more hydrophobic will diffuse faster. In addition, if there is NO proteins any molecule will diffuse down conc gradient easily across lipid bilayer.
Facilitated diffusion.
What type of process?
What is used?
Facilitated diffusion is a passive process. Goes with it’s concentration gradient.
Carrier proteins has a solute binding site on one side.
Channel proteins has a water filled pore in which specific solutes diffuse.
What is used for rapid transport in facilitated diffisuion?
Channel proteins (water filled pores.)
Can be permanently or terminally opened
What is active transport?
What is used during active transport?
Moving substance AGAINST electrochemical gradient.
Carrier proteins are used.
energy is needed
Explain the NA and K pump. What type of transport is it? What are it’s functions?
Active transport.
Actively transports NA out and K into a cell against electrochemical gradients.
3 NA out, 1K in for every molecule of ATP.
MAINTAINE membrane potential.
MAINTAINS intercellular osmotic pressure.
SUSTAINS active transport of aa and small sugars.
Active transport. Job of h+
Maintains proton gradient
Job of calcium ions active transport
Maintains gradient with outside of cell.
Intracellular storage for ions.
Explain the NA and glucose co transport mechanism.
Na and glucose both bind
Both enter
Na is restored by na and k pump
Name a second messenger system and how it is synthesised.
CMP
synthesised by an enzyme which is activated by G protein. It is called adenylyl Cyclase
Ligand. Activated receptor. Activated G protein. Activated adenylyl cyclase. Ampc synthesis
What do secondary messenger systems do?
They amplify signal and mediate effects of a signal molecule inside the cell.
How does cyclic AMP work?
It activated PKA.
This enzyme catalyses transfers of P group from ATP to serines or theonines I’d target proteins.
This regulates their activity.
Where is PKA found?
It is found in most animal cells and accounts for cyclic CMP affects inn these cells.
