Textbook Question
Write a single sentence, using no more than 25 words, to summarize each of the following cellular processes:
Diffusion
2. Cell Chemistry & Cell Components
Simple and Facilitated Diffusion
Multiple Choice
Which of the following does not accurately describe a channel or a carrier?
A
Channel – open to both sides of the membrane simultaneously.
B
Carrier – open to one side of the membrane at a time.
C
Carrier – requires a conformation change to complete function.
D
Channel – not selective for molecules that move through it.
Verified step by step guidance1
Understand the basic function of channels and carriers in cell membranes. Channels are protein structures that allow specific molecules or ions to pass through the membrane, while carriers are proteins that transport substances across the membrane by changing shape.
Recognize that channels are typically selective, meaning they allow only certain molecules or ions to pass through based on size, charge, or other properties. This selectivity is crucial for maintaining cellular homeostasis.
Identify that carriers operate differently from channels. Carriers bind to a specific molecule on one side of the membrane, undergo a conformational change, and release the molecule on the other side. This process is often selective and can be active (requiring energy) or passive.
Evaluate the statement 'Channel – not selective for molecules that move through it.' Given the understanding that channels are generally selective, this statement does not accurately describe a typical channel.
Conclude that the statement 'Channel – not selective for molecules that move through it' is incorrect because it contradicts the fundamental characteristic of channels being selective for specific molecules or ions.
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