3 types of lipids

Answer 1

First thing I thought of when I saw lipids was phospholipids.

"III. Lipids - Fats, oils, phospholipids, and steroids - All are hydrophobic (water-hating)! 3 main types:

1. Triacylglycerols (fats and oils)

Structure: Made from 1 glycerol + 3 fatty acid tails = tri-acylglycerol

Example: Fats: Butter, lard Oils: Corn oil, olive oil, margerine

Note: Vary in length and location of double bonds in tail (we will talk about the significance of these bonds in "nutrition" below.)

TWO major functions of fats and oils:

A. Energy storage. Fats are a more compact fuel than starch.

Fat contains twice the energy-rich (C-H) bonds as glucose

Fat stores twice as much energy as glucose

Fat produces twice as many calories (9 kcal/gm vs 4 kcal/gm) when burned

Unfortunately, you need to put twice as much energy to burn off a pound of excess fat than you do of glycogen...

B. Cushions and insulates the body and nerves. Each and every one of your nerves is wrapped in a lipid-rich layer called the myelin sheath.

2. Diacylglycerides (phospholipids): lipid bilayers (the plasma membrane of every cell and the membranes within eukaryotic cells)

Structure - similar to a triacylglycerol, but has only 2 fatty acid tails, and in addition has a phosphate group = (1 glycerol, 2 fatty acids, and a -PO4)

The -PO4 makes the glycerol "head" water soluble, or hydrophilic.

The long hydrocarbon tail is hydrophobic.

Function: Due to this "amphipathic" nature (both water-loving and water-hating regions in a single molecule), phospholipids self assemble into bilayers that shield the tail from water = forming membranes (phospholipid bilayers!).

3. Steroids: (cholesterol, steroid hormones)

Structure: Considered to be a "cousin" of fats - and are made from lipids. Have no fatty acids in their structure, but are very hydrophobic , see Fig 3.10b in your book

Functions of Chloesterol:

(1) Help to maintain membrane fluidity, pliability and resilience in membranes of animals, which have high amounts or rigid, saturated fatty acids.

(2) Sex hormones (testosterone, estrogen and progesterone) are all made from cholesterol

Cholesterol gets a 'bad rap" in our diet, but has CRUCIAL roles in the functioning of our cells - we couldn't live without cholesterol!!!

However, too much cholestereol in the diet is known to be a factor in atherosclerosis and Heart disease.

Cholesterol circulates in the bloodstream bound to carrier 'lipo-proteins'. High Density Lipoprotein (HDL - the "Good" kind) carries blood cholesterol to the liver where is can be eliminated from the body. Low Density Lipoprotein (LDL - the "Bad" kind) deposits blood cholesterol in the artery walls, where it can lead to constriction of blood vessels,heart disease, heart attacks, etc."

If you are thinking of the kind of fats on labels: mono, poly and sat. Sat is worse. Mono and poly are better than other fats. Also partially hydrogenated soybean oil andtrans fats are really bad for you.

Answer 2

1. Monounsaturated fats

2. Polyunsaturated fats

3. Saturated fats

Of course, there are many different kinds of lipids. The above are just three examples.

Answer 3

Triglycerides, storage. Steroids, transport. Phospholipids, so many functions