Multiple Choice
The diffusion of materials into a cell is largely controlled by which structure?
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6. The Membrane
Biological Membranes
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Where are phospholipids primarily found in cells?
A
Inside the cell nucleus
B
In ribosomes
C
In the plasma membrane
D
In the cytosol
Verified step by step guidance1
Phospholipids are a type of lipid molecule that are amphipathic, meaning they have both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions. This property is crucial for their role in cells.
The primary location of phospholipids in cells is in the plasma membrane, which is the outer boundary of the cell. The plasma membrane is a bilayer structure composed mainly of phospholipids, along with proteins and cholesterol.
The hydrophilic heads of the phospholipids face outward toward the aqueous environment (both inside and outside the cell), while the hydrophobic tails face inward, away from water. This arrangement forms a stable barrier that separates the cell's internal environment from the external environment.
Phospholipids are not found in the cell nucleus, ribosomes, or cytosol as their primary role is structural, forming the plasma membrane and other membrane-bound organelles like the endoplasmic reticulum and Golgi apparatus.
To summarize, phospholipids are primarily found in the plasma membrane, where they play a key role in maintaining the cell's integrity and regulating the movement of substances in and out of the cell.
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