Biology 12-1.2c Lipids

Fat

is created from Glycerol and fatty acids.

Steroids

are composed of a backbone of four fused carbon rings and are formed from a cholesterol precursor in body cells. Steroids have characteristics similar to fats. Some steroids differ from others by the arrangement of atoms in the carbon rings and the groups attached to the backbone. Testosterone (produced in the testes of males) and estrogen (produced in the ovaries of females) are synthesized from cholesterol.

Lipids

are diverse in structure and function, but they are unable to dissolve in water. Lipids are non-polar (lack polar groups), so they have no electrical attraction to polar solvents, such as water. Because of this, lipids are insoluble.

Phospholipids

are special fat molecules that make up most of the cell membrane. Essentially, phospholipids are constructed similar to neutral fats (triglycerides), except a phosphate group takes the place of one of the fatty acids.

Triglycerides

An energy-rich compound made up of a single molecule of glycerol and three molecules of fatty acid, and serves as a major component of animal and plant oils and fats.

Name two different types of steroids.

Any two of cholesterol, sex hormones (testosterone or estrogen), or bile fluids.

Name two reasons why cholesterol is important in our bodies.

Cholesterol is a component of our cell's plasma membrane and is a precursor for other steroids, such as bile salts, testosterone, and estrogen.

Why are fats referred to as triglycerides?

Fat molecules are called triglycerides because they are composed of three fatty acid molecules.

Neutral Fats (Fats and oils)

Fats and oils form when one glycerol molecule reacts with three fatty acid molecules. Fatty acids can be unsaturated (have double bonds between carbon atoms) or saturated (have no double bonds between carbon atoms). Fatty acids are long chains of carbon atoms with hydrogen atoms attached to them.

Suppose you are viewing a model of a fatty acid. How can you determine if the model represents a saturated or an unsaturated fat?

If the model represents a saturated fat, it will have the maximum number of hydrogens on the fatty acid chains and there will be no covalent bonds between the carbon atoms. It is saturated with all the hydrogens it can hold. An unsaturated fat will have double bonds between any two carbon atoms that have fewer than two hydrogens attached to them.

Saturated fatty acids

Saturated fatty acids are able to hold as much as possible. It has a structure filled with all hydrogen bonds it can hold and, as a result is heavier, denser, and more solid. Most saturated fats are of animal origin like meat, dairy and eggs.

Describe the basic structure of a steroid, and identify how steroids differ in structure from each other.

Steroids are composed of a backbone of four fused carbon rings and are formed from a cholesterol precursor in body cells. Steroids differ from each other by the arrangement of atoms in the carbon rings and the groups attached to the backbone.

What is the process to form fats?

The glycerol molecule attaches to a fatty acid chain by dehydration synthesis.

Phospholipids are special fat molecules that make up most of the cell membrane. How do the structure of phospholipids and neutral fats differ?

The structure of phospholipids is similar to neutral fats (triglycerides), except a phosphate group takes the place of one of the fatty acids.

Unsaturated fatty acids

Unsaturated is a fatty acid that is not completely filled with all the hydrogen it can hold. Because of that, it's less heavy and less dense like liquid oil. Monounsaturated fat has one unfilled spot. Examples of monounsaturated fat