University:
York University
Course:
BIOL 2020 | Biochemistry
Academic year:

2023
Views:

280

Pages:

2
Author:

Nick T.

Membrane Lipids Types of Membrane Lipids Phospholipids: Derived from glycerol, have an ester link between phosphoric acid and glycerol. Contain a phosphate group. Sphingolipids: Derived from sphingosine, have an amide bond between sphingosine and a fatty acid. Contain a sphingosine backbone. Structure of Membrane Lipids Polar head: Hydrophilic part of the molecule. Can be a phosphate, amine alcohol, or carbohydrate. Hydrophobic tails: Non-polar part of the molecule. Can be fatty acids or sphingosine. Glycerophospholipids Similar to triglycerides but have 2 fatty acids instead of 3. Missing fatty acid is replaced by a highly polar phosphate group. Sphingolipids Contain sphingosine backbone. One fatty acid attached by an amide bond. Easy to recognize by the amide bond. Membrane Lipids Molecules that form cell membranes. Two hydrophobic tails. Polar head. The fatty acids can be saturated or unsaturated. Membrane Lipids Proteins are embedded in the bilayer. Integral membrane proteins have hydrophobic amino acids spanning the bilayer. Peripheral membrane proteins are associated with the membrane surface. Glycolipids Membrane lipids that use carbohydrates as the polar head. Functions as receptors for chemical messengers. Cell Membranes Composed of two parallel sheets of membrane lipids arranged tail to tail. Lipid bilayer surrounds a water droplet. Proteins can move sideways through the membrane. Membrane Fluidity Membranes are fluid and can change shape. Small holes can form and close. Non-polar molecules can diffuse through the membrane. Cis-trans isomers affect fluidity. Cholesterol decreases fluidity.