Fats and Lipids

Fats or Lipids Used by the body for: stored energy, insulation, and cell membranes. In cell membranes fats called phospholipids help regulate the water and ions going in and out of the cell membrane. Other uses of fats by the body include the production of cholesterol, some hormones, skin oils, and ear wax. Fats are broken down into fatty acids by enzymes, bile salts, and acid in the small intestine before being absorbed into the blood. Fats have twice as many calories per gram than a carbohydrate. Fats are more difficult to digest than carbos, and so are often stored The largest category or type of fat is called a triglyceride.

Fats or lipids cont. Two categories of triglycerides are: Saturated fats Come from animals Solid at room temperature Contain no double bonds between the carbons. They have the maximum amount of hydrogen in their structure possible, thus, saturated with hydrogen. Noted for producing LDL cholesterol. This type of cholesterol contributes to heart disease in conc. Unsaturated Fats Come from plants Oils at room temperature due to having a very low melting point. Contain at least one double bond between the carbons. Considered to be healthier due to the body’s predisposition for converting them into HDL cholesterol.HDL prevents heart disease. (However, one’s cholesterol level is greatly influenced by genetics)

Fats or lipids cont. Two reactions of fatty acids Saponification or making soap. Uses a fat (lard or oil) and NaOH Heating the fat with NaOH causes the triglyceride to separate into a glycerol molecule and 3 fatty acids. The fatty acids are molecules with a polar head and nonpolar tail which means that they can intersperse among both polar and nonpolar substances. (Zum p. 1111) Addition reaction with Iodine Used to determine the number of double bonds in a fatty acid. The I2 which is purple, is attracted to the double bonds in a fatty acid. The I2 breaks the double bond and attaches to the fat. This reaction is easy to do and see in the lab because one mole of I2 breaks one bond in one mole of fat, and there is a distinct color change from purple to colorless when the I2 breaks the double bond. I2 is attracted to the valence e- in the double bonds.

Two examples of fatty acids

Triglycerides continued Triglycerides consist of 3 fatty acids and one glycerol molecule. If one of the fatty acids is saturated than the triglyceride is considered to be a saturated fat. Our bodies can convert triglycerides into different types or categories of fats which are used for other purposes.

Fats or lipids cont. 3 fatty acids + one glycerol combine to make

One triglyceride

Storage of fats Fats are stored in specialized tissue called adipose. The cells in adipose can expand and contract like a balloon to store the fats. Adipose tissue is located between muscles and skin, and between internal organs. Some people call adipose tissue cellulite.

Adipose tissue

Diagram of adipose tissue

Food pyramid