LIPIDS

Lipids Made up of C, O, H Types & Functions: Fats & Oils: energy storage & insulation Phospholipids: building blocks of cell membranes Steroids: structure & signaling

1. Fats & Oils (triglycerides) Most familiar a.k.a. neutral fat Fats – animal origin, solid at room temp. Oils – plant origin, liquid at room temp.

In the body fat functions as: Insulation against heat loss Protective cushion for major organs Long term energy storage (excess glucose  fat)

Structure: 1 glycerol + 3 fatty acids

Formation of a triglyceride

Neutral molecule (no charges) Nonpolar Neutral molecule (no charges) What does this mean for how it interacts in water?

All are insoluble in water (immiscible with water) = HYDROPHOBIC Soluble in other non-polar substances

FATTY ACIDS COME IN 2 Types: SATURATED & UNSATURATED

SATURATED Fatty Acids Saturated fats have saturated fatty acids All C-C bonds are SINGLE Solid at room temperature Ex. The animal fats Bacon fat Butter Lard

the more highly saturated the fat, the more energy it provides

UNSATURATED Fatty Acids unsaturated fats have unsaturated fatty acids some of the C-C bonds are DOUBLE liquid at room temperature (“kinks” formed by dbl bonds prevent close packing) Ex. Plant Oils Canola oil Safflower oil Olive oil

Triglyceride - Unsaturated

Double bonds create kinks in the fatty acid tails  fluid consistency

G l y c e r o 2. Phospholipids Phosphate Fatty Acid A phospholipid is similar to a triglyceride. It only has two fatty acids attached to a glycerol. *In addition, a phosphate molecule will also attach to the glycerol.

2. Phospholipids similar to triglycerides except that a phosphate group replaces one of the fatty acids thus elements present are = C, H, O, P Negatively charged polar heads are “hydrophilic” & soluble in water Nonpolar tails are “hydrophobic” & turn away from water whenever possible

~ polar head faces out / non-polar tails face in ~ PL’s make the backbone of cell membranes ~ polar head faces out / non-polar tails face in ~ Creates the lipid bi-layer we see in cells

Magic Milk?

EMULSIFICATION

So What? Bile - that’s what.

Backbone of 4 fused carbon rings 3. Steroids Steroids are made of several carbon rings. These carbon rings are the backbone of this type of lipid. Backbone of 4 fused carbon rings

Differ by arrangement of atoms in the rings No fatty acids Different functional groups attached

Important Steroids Cholesterol Estrogen Testosterone Vitamin D There are several important steroids in the body. *Cholesterol is a steroid. It is used along with the phospholipids the make up the cell membrane. *Vitamin D is a steroid that helps regulate the absorption of calcium from the intestines. *Estrogen in a female steroid that develops the feminine traits. It also helps to deposit calcium into bones. *Testosterone is a male steroid that develops masculine traits including the enlargement of muscles.

Cholesterol Component of plasma membrane (maintains structure & fluidity) building block for several steroids (e.g. testosterone & estrogen)