Ch 3: Lipids

lipids

diverse group of hydrophobic non-polar hydrocarbons

function

• long-term energy stores insulation from environment for plants and animals

• building blocks for some

• important component of cell membranes

examples of lipids

fats, oils, waxes, phospholipids, steroids

2 main components of fats

glycerol and fatty acids

triacylglycerol

formed by joining 3 fatty acids to a glycerol (3C) backbone

how are the glycerol molecules attached to the fatty acids?

ester linkage

how many molecules of water are released in an ester linkage?

3

saturated fatty acids

• contain no C=C double bonds in the backbone

• pack tightly and exist as solids at room temperature

• may be associated with cardiovascular disease :(

unsaturated fatty acids

• contain at least 1 C=C double bond in backbone

• most are liquids at room temperature (oils)

monounsaturated fat

1 = bond

polyunsaturated fat

> 1 = bond

cis configuration

hydrogens on the same side of chain/=

trans configuration

hydrogens on opposite side of chain/=

cis acids

• have kink in chain

• cannot be tightly packed

• liquid at room temp

trans acids

• have no kink

• can be created through processing

• foods with trans fat may increased LDL cholesterol in humans

• more solid?

essential fatty acids

• required but not synthesized by body, must be part of diet

• omega-3 fatty acid, omega-6 fatty acid (heart healthy → reduce risk of heart attacks, reduce triglycerides in blood, lower blood pressure)

more alcohol → more _______________

hydrophobic

phospholipid

• molecule with 2 fatty acids and modified phosphate group attached to a glycerol backbone

• has a polar head b/c of the phosphate group

• nonpolar tail

amphipathic structure

structure that is both polar and nonpolar

steroids have….

• closed ring structure

• 4 linked carbon rings

• many have a short tail

characteristics of steroids

1. hydrophobic

2. insoluble in water

most common steroids

cholesterol

cholesterol characteristics

1. synthesized in liver

2. precursor to other hormones such as testosterones and estradiol

3. precursor to vitamin d

4. precursor to bile salts