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Cell Membrane Structure and Chemistry

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Questions and Answers

What is the approximate ratio of lipid molecules to protein molecules in the plasma membrane?

50:50
50:1 (correct)
2:1
1:1

What is the primary function of the phospholipid bilayer in the plasma membrane?

To facilitate cell signaling pathways
To regulate the transport of molecules across the membrane
To form a barrier between the cell and its environment (correct)
To provide structural support to the cell

What type of lipids are found only in the layer of the plasma membrane that faces the extracellular fluid?

Proteins
Phospholipids
Glycolipids (correct)
Cholesterol

What is the main difference between the hydrophilic and hydrophobic regions of the phospholipid molecule?

The hydrophilic region is water-loving and the hydrophobic region is water-fearing (B) Signup and view all the answers

What is the primary component of the phospholipid molecule that makes it amphipathic?

The phosphate-containing head (D) Signup and view all the answers

What is the approximate percentage of phospholipids in the plasma membrane?

75% (C) Signup and view all the answers

What is the primary function of the plasma membrane in cellular communication?

Interaction with other body cells and ligands (D) Signup and view all the answers

What is the main cation present in the extracellular fluid (ECF)?

Na+ (B) Signup and view all the answers

What is the term used to describe the difference in chemical compositions between the cytosol and the ECF?

Electrochemical gradient (C) Signup and view all the answers

What is the primary function of selective permeability of cell membranes?

Control of what enters and leaves the cell (C) Signup and view all the answers

What is the main anion present in the cytosol?

Both b and c (B) Signup and view all the answers

What is the purpose of maintaining an electrochemical gradient across the cell membrane?

To separate the cellular contents from the ECF (C) Signup and view all the answers

What is the main difference between integral and peripheral proteins?

Integral proteins extend across the phospholipid bilayer. (C) Signup and view all the answers

What is the function of some integral proteins that act as channels?

To allow certain substances to flow into or out of the cell. (A) Signup and view all the answers

What is the primary function of transporter proteins?

To move substances from one side of the membrane to the other. (B) Signup and view all the answers

What is the orientation of the sugar portion of a glycoprotein?

Faces the ECF. (D) Signup and view all the answers

What determines the functions a cell can perform?

The type of membrane proteins present. (B) Signup and view all the answers

What is the function of some integral proteins that serve as recognition sites?

To act as receptors. (B) Signup and view all the answers

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