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Multiple Choice
What do the segments of a transmembrane protein that cross the lipid bilayer usually consist of?
A
Phosphate groups
B
Hydrophilic amino acids
C
Carbohydrate chains
D
Hydrophobic amino acids
Verified step by step guidance
1
Understand the structure of the lipid bilayer: The lipid bilayer is composed of phospholipids with hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. This structure creates a hydrophobic interior within the membrane.
Recognize the nature of transmembrane proteins: Transmembrane proteins span the entire lipid bilayer, meaning they must interact with both the hydrophilic and hydrophobic regions of the membrane.
Identify the properties of amino acids: Amino acids can be hydrophilic or hydrophobic. Hydrophilic amino acids are attracted to water and are typically found on the exterior surfaces of proteins, while hydrophobic amino acids avoid water and are found in the interior or membrane-spanning regions.
Determine the composition of the membrane-spanning segments: The segments of transmembrane proteins that cross the lipid bilayer are typically composed of hydrophobic amino acids. This allows them to interact favorably with the hydrophobic interior of the lipid bilayer.
Conclude why hydrophobic amino acids are used: Hydrophobic amino acids stabilize the protein within the lipid bilayer by interacting with the hydrophobic tails of the phospholipids, ensuring the protein is properly anchored and functional within the membrane.