Fats, Oils Waxes, Phospholipids, Soaps, Steroids
ORGANIC MOLECULES : LIPIDS
Lipids:
- Fats, oils waxes, phospholipids, soaps, steroids
- We eat lipids as part of our food. Our bodies are capable of producing them as well as metabolizing them. Next to glucose, fats are the second most important energy molecules for us. Unfortunately, as a survival mechanism, we store them in adipose (fat) cells.
- Function: Long term energy reserve.
- Elements: Carbon, hydrogen, and oxygen but the H:O ratio is greater than 2:1.
- Structure: neutral fats like hard fats and oils consist of the monomers fatty acids and glycerol.
- Fatty acids are non-polar chains of carbon and hydrogen with a carboxylic acid end. A tremendous number of variations exist between fatty acids.
- Some are saturated (without double bonds)
- Some are unsaturated (with double bonds)
Various Lipids and Their Structures:
**Neutral Fats- 1 molecule of glycerol in combination with 1, 2 or 3 molecules of fatty acids.
- Monoglyceride-one fatty acid attached to a glycerol.
- Diglyceride- two fatty acids attached to a glycerol.
- Triglyceride- three fatty acids attached to a glycerol.
a)Fats (saturated fats): Usually of animal origin and are solid at room temperature.’
Examples : Adipose tissue, Lard, Butter
b)Oils (unsaturated fats): Usually of plant origin and are usually liquid at room temperature because of the double bonds.
- Polyunsaturated fats have many double bonds therefore few hydrogen bonds.
Examples: Vegetable oils
c)Waxes: Relatives of fats, they have fatty acids joined to a long chain alcohol rather than glycerol.
d)Sterols: Compounds such as the sex hormones, cholesterol, anabolic steroids and some of the ingredients of bile.
- Instead of a straight chain of carbons, steroids are nonpolar ring structures.
- They are insoluble in water therefore considered a lipid.
- Example: Cholesterol- important part of cell membrane and the protective cover around nerve fibers.
- Note: Cholesterol is important, but too much results in fatty deposits inside arteries. This narrows the pathway for blood so the heart has to pump harder to push the blood through the body.
-The result is an increase in blood pressure.
- Cholesterol is the important part of the cell membrane and the protective cover around nerve fibers.
- Steroids are able to pass through cell membranes and combine with receptors in the cell. The steroid receptor complex activates certain genes leading to protein synthesis. Increased protein synthesis increases muscle development.
e) Phospholipids
- Phospholipids are a variation of a triglyceride where one of the fatty acids is replaced with a phosphate and a nitrogen-containing group.
- This creates a polar region and consequently phospholipids can mix with both polar (likes water) and non-polar (dislikes water) materials.
- Phospholipids are very important in cells as they form the majority of the cell’s membranes.
- Because they have water-soluble heads and insoluble tails. They tend to form a thin film on water with their tails in the air. Like above.
- If surrounded by water they arrange themselves in a bubble with their tails inward. (This would be called a rudimentary cell membrane)
- The heads of the phospholipids are polar and are said to be water loving. (Hydrophilic)
- The Tails of the phospholipds are non polar and are said to be water hating. (Hydrophobic)
Cell Membrane: