Biological Membranes

Question 1

Fatty Acids and Membrane Fluidity

Answer 1

• Unsaturated fatty acids on triacylglycerols increase membrane fluidity.
• Saturated fatty acids on triacylglycerols decrease membrane fluidity.

Question 2

Cell-Cell Junctions

Answer 2

• Comprised of Cell Adhesion Molecules.
• Gap Junctions (Connexons): Allow for direct cell-cell communication and permit movement of water and certain solutes, but not proteins.
• Tight Junctions: Prevent paracellular leakage of water and solutes across epithelial layer; form watertight seal.
• Desmosomes: Bind adjacent cells by anchoring to their cytoskeletons; desmosomes attach epithelial cells to each other, while hemidesmosomes attach epithelial cells to basement membrane.

Question 3

Mitochondrial Membranes

Answer 3

• Outer Mitochondrial Membrane: Highly permeable to ions and small proteins and contains cholesterol; intermembrane space between two layers.
• Inner Mitochondrial Membrane: More restricted permeability, has cristae (infoldings that increase surface area), contains cardiolipin but does not contain cholesterol, and encloses matrix.