Lipids Biomolecule #2

Lipid Structure Lipids are molecules made mostly of carbon, hydrogen, and very few oxygen. The ratio of hydrogen to oxygen is greater than 2:1 The monomer of a lipid is made up of glycerol and fatty acids. Lipids generally form long chains except in steroids. Lipids are hydrophobic. Lipids do not dissolve in water.

Lipid Structure: Saturated vs. Unsaturated Fatty Acid Type Drawing Food examples: Saturated solid at room temperature (no double bonds = bad) Unsaturated liquid at room temperature (double bonds = good) Peanut Butter Meat Butter Olive oil Avocado Fish

Lipid Functions Energy storage for the body (long term energy) Insulation Cell membrane structure (phospholipid bilayer) Chemical messengers that carry messages through the blood stream. Protection against water lose; waterproofing.

1. Fats: Triglycerides found in foods and the human body. Examples of Lipids 1. Fats: Triglycerides found in foods and the human body. Solid at room temperature Energy storage in animals Contain 3 saturated fatty acids Saturated fat and fatty acid Stearic acid

Body Fat – stores energy, insulates and protects the organs Excess energy is converted to fat Sea mammals rely on fat to keep warm

2. Oils: Triglycerides found in plants. energy storage in plants contain 3 unsaturated fatty acids liquid at room temperature Unsaturated fat and fatty acid Double bond causes molecule to bend Oleic acid

3. Waxes: Lipids that repel water - found on the surface of leaves - found on animal hair to keep it pliable - found on the feathers of water birds to prevent them from becoming waterlogged

4. Phospholipids Glycerol only 2 fatty acids (not 3 like fats and oils) 3rd fatty acid is replaced by a phosphate molecule Please draw and label the phospholipid.

(a) Structural formula (b) Space-filling model Phospholipid structure Phosphate molecule forms a hydrophilic (water loving) head Fatty acid molecules make up a hydrophobic tails CH2 O P CH C Phosphate Glycerol (a) Structural formula (b) Space-filling model Fatty acids (c) Phospholipid symbol Hydrophobic tails Hydrophilic head Hydrophobic tails – Hydrophilic head Choline + Figure 5.13 N(CH3)3 10

Phospholipids create the structure of cell membranes 2 layers of phospholipids Phosphates face out – interact with water Lipid tails make a middle layer that repels water Phospholipids separate the contents of the cell from it’s surrounding environment Hydrophilic head WATER Hydrophobic tail 11

Myelin - phospholipid that insulates nerve cells

5. Cholesterol connected rings of carbon component of cell membrane – adds to the integrity of the membrane used to make steroids

6. Steroids: Lipids that act as Hormones Hormones are chemical messengers - produced in one part of the body, they travel to and cause changes in another part of the body Hormones control: mood growth development the way our bodies use food the reaction of our bodies to emergencies

Steroids are Derived From Cholesterol Estrogen Testosterone