Plasma Membrane Transport

Questions from the Plama Membrane Transport Homework

the structure of aquaporins is best described as

A homotetrameric protein complex

phosphorylation can modulate ion channel gating by:

Altering the channel's response to voltage or ligands.

How does the lipid solubility of a solute impact its ability to cross the plasma membrane?

Solutes that are lipid-soluble can easily diffuse across the membrane without the need for transport proteins.

What role do ion channels play in facilitated diffusion?

They allow specific ions to pass through the membrane according to their concentration gradient.

Which of the following describes the role of the sodium-potassium pump (Na+/K+-ATPase) in cellular homeostasis?

It actively transports Na+ out of the cell and K+ into the cell.

Which of the following best describes the mechanism by which voltage-gated ion channels operate?

They open in response to changes in membrane potential.

What determines the direction of passive transport via a transporter protein?

The concentration gradient of the solute across the membrane.

Inhibition of the Na+/K+ATPase pump would have what effect on secondary active transport processes?

Decrease in secondary active transport efficiency due to a loss of the electrochemical gradient necessary for the transport of other molecules.

Which of the following is a consequence of aquaporin dysfunction in human physiology?

Dehydration or overhydration. (Aquaporins facilitate the transport of water via osmosis , so their dysfunction would impair osmotic balance and lead to disorders of water homeostasis.)

What structural feature is most commonly associated with the function of transmembrane proteins?

Alpha-helices and beta-barrel

Transporters, in contrast to channels, work by

specific recognition of transport substrates. (Transporters have a specific solute-binding site and bind a solute to transport it.)

What category of membrane transport are channels a part of?

facilitated diffusion. (Channels facilitate passive diffusion and are a part of passive transport.)

Which of the following best describes the behavior of a gated channel?

It requires a stimulus to change from closed to open. (Gated channels have open and closed configurations and require a stimulus (voltage, ligand, or mechanical stress) to switch states.)

What is the primary purpose of the K+ leak channels in the gut epithelial cells?

To keep the Na+ pump fully functional.