Cell Membranes and Transport Flashcards
What is a glycocalyx and what are its 3 main functions?
A carbohydrate shell that covers the outer sheet of many membranes.
- Protection
- Cell adhesion
- Cell identification
Describe Niemann-Pick Disease.
Caused by deficiency in Acid Sphingomyelinase (A-SMase). Leads to accumulation of SM.
Symptoms: Hallmark “cherry red spot” in the eye, hepatosplenomegaly, neurological damage
What are the products of A-SMase break down of sphingomyelin?
Ceramide and phosphoryl choline
What is erythroblastosis fetalis?
Disease where there is incompatibility between the blood of the mother and the fetus. Occurs when mom is Rh- and fetus is Rh+, leading to mom producing antibodies during the pregnancy.
What is spur cell anemia?
Elevated levels of cholesterol bound to RBC membrane. Creates thorny projections in RBCs that eventually cause lysis. Leads to hemolytic anemia.
What is cystinuria?
Defect in transporter for cystine. Leads to formation of cystine crystals or kidney stones.
What is Hartnup disease?
Defect in transporter for non-polar or neutral amino acids.
Symptoms: ataxia, photodermatitis, photosensitivity
How do Cardiotonic drugs work and what are they used to treat?
Inhibits Na/K-ATPase which inhibits the activity of Sodium Calcium Exchanger (NCX). Leads to increase in sarcoplasmic Ca2+, increasing the contractile force of cardiac muscle cells. Used to treat CHF, A Fib, and dysrhythmias.
Describe the mechanism and symptoms of cystic fibrosis.
Defective CFTR transporter that leads to Cl- buildup inside cell which is compensated by Na+ to make salt. Leads to thinker mucous and susceptibility to bacterial infections.
Describe the mechanism of P type ATPases.
Uses ATP hydrolysis to drive transport against gradient. Transporter forms covalent bond with phosphate on a conserved aspartate residue.
What is the main difference between ABC Transporters and P-Type ATPases?
ATP hydrolysis is the last step of ABC Transporters, used to reset transporter to its original state. For P-Type ATPases, ATP is hydrolyzed to create the enzyme-phosphate intermediate.
Describe the mechanism of sodium glucose transporter (SGLT1).
A type of secondary active transport that mediates the unidirectional movement of Na+ and glucose across SI cells. Moves Na+ down its gradient and glucose against.
Describe the mechanism of Na+-Ca2+ Exchanger (NCX).
An antiporter (secondary active transport) that imports 3 Na+ down its gradient and 1 Ca2+ against its gradient.
