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Multiple Choice
Which of the following best describes an integral membrane protein?
A
A protein loosely attached to the membrane surface via non-covalent interactions.
B
A protein that spans the entire lipid bilayer and is embedded within the membrane.
C
A protein that is covalently attached to a lipid molecule but does not span the membrane.
D
A protein that is found only in the cytoplasm and not associated with the membrane.
Verified step by step guidance
1
Step 1: Understand the concept of integral membrane proteins. Integral membrane proteins are proteins that are embedded within the lipid bilayer of a cell membrane. They typically span the entire bilayer and interact with both the hydrophobic interior and hydrophilic exterior of the membrane.
Step 2: Differentiate integral membrane proteins from peripheral membrane proteins. Peripheral membrane proteins are loosely attached to the membrane surface via non-covalent interactions, whereas integral membrane proteins are embedded within the bilayer and often span it completely.
Step 3: Consider the structural characteristics of integral membrane proteins. These proteins often have hydrophobic regions that interact with the lipid bilayer's hydrophobic core and hydrophilic regions that interact with the aqueous environment inside and outside the cell.
Step 4: Evaluate the options provided in the question. The correct description of an integral membrane protein is 'A protein that spans the entire lipid bilayer and is embedded within the membrane.' This distinguishes it from proteins that are loosely attached, covalently attached to lipids, or found only in the cytoplasm.
Step 5: Confirm the answer by matching the description of integral membrane proteins with the correct option. Integral membrane proteins are essential for various functions, such as transport, signaling, and maintaining the structural integrity of the membrane.