Chapter 10

Major functions of lipids

energy storage, membrane structure, signaling

Where is omega (w) and what does w-3 mean?

Omega is the terminal carbon of the tail, w-3 means a double bond is 3 carbons away from the terminal carbon

What are triacylglycerides and where are they found

Fat/energy storage in cells, found in fats and oils in animals and plants

Bilayer forming ability of fatty acids

Form a wedgelike van der waals envelope, form micelles

Bilayer forming ability of glycerophospholipids

Have a cylinder like shape, makes a flat surface/layer

Bilayer forming ability of tracylglycerols

Hace a small head component than tail, make globular aggregates

What are membrane lipids and what are the three main classes

Combine fatty acids and polar head groups through covalent bonds, Phospholipids, Glycolipids, and Cholesterol

Four components of Phospholipids

1. Fatty acid tail groups

2. Platform where fatty acids are attached

3. Phosphate group

4. Alcohol condensed to phosphate

Cholesterol structure and how it impacts saturated and unsaturated fats

Four ring system, mostly unsaturated, slightly polar head group. Allows sat fats to be more liquid and unsat fats to maintain its shape: overall stabilizes lipids

Transition temperature

The temperature where membranes undergo a phase transition

What occurs above transition temperature

High fluidity, looser packing, increased permeability of membrane

What occurs below transition temperature

Thicker membrane, forms a gel-like solid, decreased fluidity

What increases transition temperature (need a higher temp to reach)

1. Chain length (longer chain = need higher temps)

2. Degree of saturation ( more saturated lipids = need higher temps)

Why is it important to have a mixed lipid composition in the membrane bilayer (inner and outer layer)

Maintains membrane fluidity over a range or temperatures

Lipid rafts

membrane subdomains that are high in cholesterol and glycosphingolipids (have large head groups), float, stay together as a group

Peripheral (EXtrinsic) membrane proteins

Adhere to the surface of the membrane, attach to polar head groups, easily dissociate from the membrane

Integral (INtrinsic) membrane proteins

Tightly bound to the lipid membrane, dissociation of these proteins disrupts entropic/hydrophobic forces, embedded within the hydrophobic core

Transmembrane proteins

Have a sequence that spans the membrane, act as bridges that connect the inside of a cell to the outside environment

Porins

Beta-sheet transmembrane proteins, exterior is hydrophobic (interacts with the membrane) and interior is polar