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Cell Membranes Problem Set

Problem 11: Phospholipids

Tutorial to help answer the question

Phospholipids have hydrophilic and hydrophobic areas within the same molecule. This dual nature of the molecule is describe by the term:

A. amphipathic.
B. electrostatic.
C. polar.
D. non-polar
E. ionic.


Cell membrane

Lipid molecule with hydrophobic and hydrophilic ends Legend for lipid molecule described in text

Carbon (gray) and hydrogen (white) are the only atoms in the fatty acid tails, making this part of the molecule hydrophobic.

The other end of the molecule includes oxygen (red), nitrogen (blue), and phosphorus (yellow) giving a hydrophilic character to the molecule.

Proteins embedded in the cell membrane

Proteins can also be amphipathic.

Many integral membrane proteins have sequences that are very hydrophobic and are embedded in the membrane.

Other areas of the protein are hydrophilic and will be exposed to the aqueous solution on either the inside or outside of the cell.

Integral and peripheral protein of membrane

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