What are the factors that affect membrane fluidity?
Dependent on the fatty acid pattern found in phospholipids, and the amount of cholesterol
What is the difference between the membranes of hepatocytes and mitochondria?
Cholesterol, sphingomyelin and phosphatidylserine in hepatocytes - cardiolipin in mitochondria
Describe how cholesterol stabilizes the membrane
increases membrane fluidity at low temps and decreases fluidity at high temps - opposite of fatty acids
What is passive transport?
Movement of a molecule by simple or facilitative diffusion with a concentration gradient by pores, gated channels or carrier proteins
What is active transport?
Movement of molecule against the concentration gradient coupled with the use of ATP.
What types of transporters use facilitative diffusion?
What are the 5 types of GLUT transporters and their functions
1- abundant in RBC and brain, 2- found in intestinal mucosal cell towards enterohepatic circulation - large Kt (low affinity) for glucose and is efficient at high concentrations. 3-dominant in neurons, 4-insulin dependent, stored inside cells (diabetes can't use these efficiently), 5-in intestinal mucosal cells toward intestinal lumen and testes for mainly fructose.
Explain the biochemical basis for diabetes
can't use GLUT-4 transporters efficiently. Insulin usually mobilizes the transport of GLUT-4 to the plasma membrane to allow influx of glucose.
Describe the primary active transport by Na/K-ATPase
uses ATP to pump in 2K and pump out 3Na - maintains membrane potential - against the gradient
Describe secondary active transport by SGLT(sodium ion coupled glucose symporter
coupled to NA/K ATPase, and uses this concentration gradient of Na created by the ATPase and SGLT cotransports one glucose and two sodium ions into the cell.
Using one's knowledge of SGLT, how would you prevent death of a child with severe diarrhea?
Use a water solution with sodium chloride and glucose to help prevent dehydration.
Describe the ABC transporter CFTR
CFTR (cystic fibrosis transmembrane conductance regulator) is a phosphorylation gated channel, uses PKA to activate cAMP to phosphorylate the channel and open it to allow chloride ions out of the cell
What is the biochemical basis for cystic fibrosis
3 base pair deletion in exon 10 which leads to the loss of single amino acid phenylalanine - leads to defective CFTR - unable to open the chloride channel and drive sodium and water with it the gradient- leads to dehydration of respiratory and intestinal linings - thick mucus - very salty sweat