Module 2 - Lesson 3-4 Flashcards
(16 cards)
What type of transport does GLUT1 perform?
Facilitated diffusion (passive transport) of glucose in erythrocytes.
What are the three types of membrane transport proteins?
Carriers, channels, and pumps.
What type of ATPase is responsible for Na+/K+ exchange in cells?
P-type ATPase.
Which ion channel is blocked by tetrodotoxin from fugu (pufferfish)?
Voltage-gated Na⁺ channel.
What is the function of aquaporins?
To transport water across plasma membranes rapidly without allowing proton hopping.
How many genes encode ABC transporters in humans?
48 genes.
How do ion channels differ from transporters in their function?
Ion channels provide fast, unrestrictive diffusion (often gated), while transporters are slower and more specific, often requiring conformational changes.
What is the difference between primary and secondary active transport?
Primary uses direct ATP hydrolysis for energy, while secondary relies on ion gradients created by primary transport to move other substances.
Why is facilitated diffusion faster than simple diffusion for some molecules like glucose?
Transport proteins lower the activation energy, enabling faster movement across membranes.
How does the chloride-bicarbonate exchanger support CO₂ transport in blood?
It facilitates the exchange of Cl⁻ and HCO₃⁻ ions, allowing efficient CO₂ transport as bicarbonate.
Why is the Na⁺/K⁺ ATPase essential for human cells?
It maintains electrochemical gradients, contributes to membrane potential (Vm), and consumes ~25% of the cell’s energy.
How would you determine the activity of an ion channel if you cannot observe it biochemically?
Use patch-clamp electrophysiology to monitor ion flow through single or few channels.
Describe the mechanism of action for the Na⁺/K⁺ ATPase.
3 Na⁺ ions are exported and 2 K⁺ ions imported per ATP hydrolyzed, generating an electrochemical gradient and membrane potential.
How can you test if a substance is transported by facilitated diffusion or active transport?
Test for movement against a concentration gradient or ATP dependence; facilitated diffusion does not require ATP.
What would happen if you added an ionophore like vancomycin to a cell culture?
It would collapse ion gradients, disrupting active transport and potentially killing cells.
How do aquaporins prevent proton transport despite moving water molecules?
Arg195 and other residues prevent formation of a continuous chain of water molecules, blocking proton hopping.
