Question

part a
in general, which of the following is (are) largely responsible for moving substances across the plasma membrane, communicating with other cells, and identifying the cell?
proteins
carbohydrates
phospholipids
cytoskeleton
nucleic acids

Explanation:

• Proteins: Integral membrane proteins can act as transporters (moving substances across the membrane), receptors (for cell - cell communication), and glycoproteins (for cell identification).
• Carbohydrates: Mainly involved in cell - cell recognition (as part of glycoproteins or glycolipids), but their role in moving substances across the membrane is limited compared to proteins.
• Phospholipids: Form the basic structure of the plasma membrane (the lipid bilayer), but their primary function is not in substance movement, communication, or cell identification as described.
• Cytoskeleton: Involved in cell shape, intracellular transport, and cell movement, not directly in the plasma - membrane - related functions mentioned.
• Nucleic acids: DNA and RNA are involved in genetic information storage and expression, not in the plasma - membrane functions.

Answer:

Proteins