The proteins that establish ionic gradients across the neuron's cell membrane are ___________.

Question

The proteins that establish ionic gradients across the neuron's cell membrane are  ___________.

BlackTom AI · Accepted Answer

Ionic gradients are created and maintained by proteins that move ions against their electrochemical gradients using energy; the prototypical example is the Na+/K+ ATPase (sodium-potassium pump), so the correct answer is b) active transporters.

Relevant concepts: cells maintain different intracellular and extracellular concentrations of Na+, K+, Ca2+, etc., and these differences are the ionic gradients. Establishing a gradient requires moving ions from lower to higher concentration or against an electrical potential, which is energetically unfavorable and therefore must be coupled to an energy source (usually ATP) — this is the hallmark of active transport. Active transporters include primary active pumps (e.g., Na+/K+ ATPase, Ca2+ ATPase) and secondary active transporters that use existing ion gradients to drive transport of other solutes.

Step-by-step reasoning:
1. "Establish" implies creating or maintaining a concentration difference against diffusion/electrical forces.
2. Only proteins that expend energy can move ions uphill; the Na+/K+ pump hydrolyzes ATP to export 3 Na+ and import 2 K+ per cycle, directly creating and sustaining the major Na+ and K+ gradients in neurons.
3. These gradients underlie the resting membrane potential and provide the driving force for action potentials and secondary transport processes.

Why other options are incorrect:
- a) Passive transporters: facilitate diffusion down an existing gradient and do not create gradients; they cannot move ions uphill.
- c) Voltage-gated ion channels: open in response to membrane potential changes to allow rapid ion flow down gradients during signaling, not to establish gradients.
- d) Ligand-gated ion channels: open in response to neurotransmitters to permit ion flow down gradients, not to build them.
- e) Leaky channels: allow small, passive ion leakage that influences resting potential but cannot generate gradients; they dissipate gradients rather than create them.

Therefore, active transporters (b) are the correct choice, matching the provided answer.

The proteins that establish ionic gradients across the neuron's cell membrane are ___________.单项选择题

类似问题

All active transport proteins are proteins. proteins would not work because they allow movement in both directions.

Which statement about ion distribution and the neuronal membrane is CORRECT?

A very short half-life for passage across a biological membrane

A major function of plasma membranes is to:

In a two-compartment model of a cell with a K +-permeable membrane and a 10-fold excess of K + in the inside compartment, how would K + ions flow across the membrane?

Why don't most mineral nutrients passively diffuse across plant cell membranes?

The figure below shows two transporters typically found in the membrane of neurons. Which feature do these transporters share?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单