Membrane Transport and Permeability Quiz

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What is the main factor that determines the rate of diffusion of a molecule across a membrane?

Presence of hydrophobic regions in the molecule

Temperature of the surrounding environment

Charge of the molecule

Size of the molecule and its association with water (correct)

What is the resting membrane potential primarily a result of?

Presence of negatively charged ions only

Active transport and passive diffusion (correct)

Concentration gradient of ions

Electrochemical gradient only

Which ion tends to diffuse out of the cell through potassium channels to reach equilibrium?

K+ (correct)

Na+

Cl-

Ca2+

What is the electrochemical gradient of a charged solute a combination of?

Concentration gradient and charge of the solute Signup and view all the answers

How do proteins associate with the plasma membrane based on their topology?

Bound by a covalently attached lipid chain Signup and view all the answers

Which ions result in a difference in electrical charge across the membrane to establish the resting membrane potential?

[K⁺] and [Na⁺] Signup and view all the answers

Which factor contributes to making the interior of the cell more negative during resting membrane potential?

[K⁺] diffusing out through potassium channels Signup and view all the answers

What type of molecules can easily pass through the lipid bilayer of the cell membrane?

Nonpolar molecules Signup and view all the answers

What is the main function of transport proteins in the cell membrane?

Facilitate the movement of specific molecules across the membrane Signup and view all the answers

What percentage of all membrane proteins are transport proteins?

30% Signup and view all the answers

Why do cells need to transfer molecules and ions across their membranes?

To maintain homeostasis Signup and view all the answers

Which part of the cell contains a liquid matrix surrounding organelles?

Cytosol (ICF) Signup and view all the answers

What allows cells to maintain different solute concentrations in their cytosol compared to the extracellular fluid?

Selective permeability of the plasma membrane Signup and view all the answers

What allows transport proteins in the cell membrane to be specific to certain molecules?

'Lock-and-key' interactions with molecules Signup and view all the answers

What is the role of Na+/Ca2+ exchange inhibitors?

Removing Ca2+ from plasma membranes Signup and view all the answers

Where is the NCKX2 Na+/Ca2+-K+ exchanger located?

Neuronal cell membranes Signup and view all the answers

What cellular mechanisms does the Na+/Ca2+ exchanger (NCX) participate in?

Exchanging Na+ for Ca2+ across the plasma membrane Signup and view all the answers

What is the main function of the Na+, K+-ATPase in animal cells?

Balancing Na+ and K+ concentrations across the plasma membrane Signup and view all the answers

What are the key roles of NCKX2 Na+/Ca2+-K+ exchanger?

Influencing synaptic plasticity Signup and view all the answers

Which organelle is NOT mentioned as a location where Ca2+ can be found in excitable cells?

Golgi apparatus Signup and view all the answers

How does the NCKX2 Na+/Ca2+-K+ exchanger contribute to cognitive functions?

By enhancing Ca2+ clearance in neuronal cells Signup and view all the answers

What types of sensations can the skin sense?

Vibration, pressure, stretch, and touch Signup and view all the answers

How do leak channels differ from gated channels in terms of functionality?

Gated channels require external stimuli to open Signup and view all the answers

What is the significance of the selectivity filter in K⁺ channels?

It dehydrates ions to facilitate their passage Signup and view all the answers

Where are aquaporins abundant and what is their function there?

Facilitate osmotic water flow in cells that secrete or reabsorb water Signup and view all the answers

How many isoforms of aquaporins have been identified in mammalian cells?

10 Signup and view all the answers

What is the role of Anti-diuretic hormone (ADH) in relation to aquaporins?

It increases the expression of aquaporins for water reabsorption Signup and view all the answers

How does Na⁺ size affect its passage through K⁺ channels?

Na⁺ cannot be accommodated by the filter due to being smaller than K⁺ Signup and view all the answers

What happens to ions as they pass through the selectivity filter of K⁺ channels?

They dehydrate and interact with carbonyl groups Signup and view all the answers

In which type of cells are aquaporins predominantly present?

Cells that secrete or reabsorb high amounts of water Signup and view all the answers

Which type of membrane transport protein forms pores for specific solute transfer?

Channels Signup and view all the answers

In which state of a transporter are the binding sites for solutes exposed to the inside of the cell?

Inward-open state Signup and view all the answers

Which type of membrane transporter undergoes a series of conformational changes to transfer solutes across the membrane?

Carriers Signup and view all the answers

What type of transport is always passive?

Transport through channels Signup and view all the answers

Which type of membrane protein interacts more weakly with solutes compared to transporters?