Multiple Choice
In cell biology, what is the primary structural component that makes up the cell (plasma) membrane?
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8. Membrane Structure
The Lipid Bilayer
Multiple Choice
In the context of the lipid bilayer, what is the primary function of the cell (plasma) membrane?
A
It acts as a selectively permeable barrier that regulates movement of substances into and out of the cell.
B
It synthesizes most cellular ATP through oxidative phosphorylation.
C
It stores genetic information and directs transcription of RNA.
D
It assembles amino acids into proteins during translation.
Verified step by step guidance1
Step 1: Understand the structure of the cell (plasma) membrane, which is primarily composed of a lipid bilayer with embedded proteins.
Step 2: Recognize that the lipid bilayer creates a hydrophobic barrier that prevents free passage of most water-soluble substances.
Step 3: Identify that the membrane's embedded proteins function as channels, carriers, and receptors to selectively allow or restrict the movement of ions, nutrients, and waste products.
Step 4: Differentiate the primary function of the plasma membrane from other cellular functions such as ATP synthesis (which occurs in mitochondria), genetic information storage (in the nucleus), and protein assembly (at ribosomes).
Step 5: Conclude that the main role of the plasma membrane is to act as a selectively permeable barrier regulating the internal environment of the cell by controlling substance movement.
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