Multiple Choice
Why do sodium ions enter a cell when gated sodium channels open?
31
views
9. Transport Across Membranes
Ion Channels and Membrane Potential
Struggling with Cell Biology?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following is a fundamental property shared by all ion channels?
A
They transport ions against their concentration gradients.
B
They allow selective passage of specific ions across the membrane.
C
They require ATP hydrolysis to function.
D
They are permanently open and never close.
Verified step by step guidance1
Understand the role of ion channels: Ion channels are proteins embedded in the cell membrane that facilitate the movement of ions across the membrane. They are crucial for maintaining cellular homeostasis and enabling processes like nerve signaling and muscle contraction.
Clarify the concept of selective passage: Ion channels are selective, meaning they allow only specific ions (e.g., Na⁺, K⁺, Ca²⁺, Cl⁻) to pass through based on factors like size, charge, and the structure of the channel's pore.
Eliminate incorrect options: Ion channels do not transport ions against their concentration gradients; this is the role of active transporters. Ion channels facilitate passive transport, allowing ions to move down their concentration or electrochemical gradients.
Address the energy requirement: Ion channels do not require ATP hydrolysis to function. They rely on the existing electrochemical gradient of ions, unlike active transport mechanisms such as pumps.
Consider gating mechanisms: Ion channels are not permanently open. Many are gated, meaning they open or close in response to specific stimuli (e.g., voltage changes, ligand binding, or mechanical forces). This ensures precise regulation of ion flow.
Related Videos
Related Practice
Ion Channels and Membrane Potential practice set
Problem sets built by lead tutorsExpert video explanations