Which statement is NOT true about the proteins in the plasma membrane?
-Proteins may be attached to the inner surface of the plasma membrane.
-The hydrophobic portion of a protein is embedded within the membrane.
-Some peripheral proteins are connected to cytoskeletal filaments.
-Integral proteins are responsible for membrane functions.
-Glycoproteins contain carbohydrate chains that are oriented toward the inner surface of the membrane.(CORRECT)
can someone explain why the last answer is correct? Thanks!
The last answer is correct because glycoproteins contain carbohydrate chains that are oriented toward the outer surface of the membrane, not the inner surface. This is because the carbohydrate chains are hydrophilic and need to be exposed to the aqueous environment outside the cell.
The correct answer is "Glycoproteins contain carbohydrate chains that are oriented toward the inner surface of the membrane." The reason this statement is not true is because glycoproteins, which are proteins with attached carbohydrate chains, have these carbohydrate chains oriented towards the outer surface of the plasma membrane, not the inner surface.
To understand why this is the correct answer, we can look at the structure and function of the plasma membrane. The plasma membrane is composed of a phospholipid bilayer, in which the hydrophilic heads of the phospholipids face outward towards the surrounding environment, while the hydrophobic tails are oriented inward, creating a barrier.
Integral proteins are embedded within the lipid bilayer, with their hydrophobic portions interacting with the hydrophobic tails of the phospholipids. These proteins play important roles in transporting molecules across the membrane, acting as channels or pumps for specific substances.
Peripheral proteins, on the other hand, are not embedded in the lipid bilayer and are often found on either side of the membrane, either attached to the inner surface or the outer surface. Some peripheral proteins are indeed connected to cytoskeletal filaments, which provide structural support to the cell.
Glycoproteins, or proteins with attached carbohydrate chains, are found on the outer surface of the plasma membrane. These carbohydrate chains act as markers for cell recognition and provide additional functionality to the membrane, such as cell adhesion or signaling.
In summary, the statement that glycoproteins contain carbohydrate chains that are oriented toward the inner surface of the membrane is incorrect, as these carbohydrate chains are actually oriented towards the outer surface of the plasma membrane.