Bio-Chemistry
Lipids
Lipids are classified as any group of large biological molecules, including fats, phospholipids, and steroid, that mix poorly, if at all, with H2O (therefore, they are usually nonpolar). They are usually made up of Carbon and Hydrogen. Lipids act as an energy source, are part of cell membranes (steroids are common), and can also act as a waterproof covering.
Phospholipids technically do not have a polymer or monomer form; however, the building blocks of lipids include glycerol and fatty acids. Lipids don't fit the definition of a polymer because only 1 glycerol can bond on to 3 fatty acids (in a polymer, the monomers can bond infinitely).
-A fatty acid has a long Carbon skeleton, with a carboxyl group at one end, and a hydrocarbon chain.
-Glycerol and fatty acids come together through an ester linkage (again, 3 fatty acids to 1 glycerol).
Saturated lipids are made up of all single Carbon bonds, are generally solid at room temperature, and usually will clog up vessels in your body (making it easier to stick to your vessels), ergo not healthy for you-this is due to the cis-trans bond not allowing the molecules to solidify.
Unsaturated lipids have at least 1 double bond, a 'kink' in its carbon chain (X's on the same side). They are generally liquid at room temperature, and its 'kink' makes it easier to flow thru blood vessels, making them the healthier fit. If there are more than one bond, then they are considered "polyunsaturated."
Types of Lipids
Phospholipids
Phospholipids are a specific type of lipid. They make up the cell membrane in a cell; because of this, phospholipids have a polar head (hydrophilic, water-loving) and a nonpolar tail (Hydrophobic, water-hating). The polar head of a phospholipid allows interactions with H2O moleucles; however, for water to pass through the cell membrance, aquaporin channels are needed to do so.
A phospholipid has 2 fatty acids to 1 glycerol (in the 3rd fatty acid's place is a phosphate group), which creates hydrophobic and hydrophilic ends.
*Fats do not mix with H2O, making them nonpolar and hydrophobic.
Steroids and Hormones
Steriods are a type of lipids; hormones can be classified as both proteins and lipids.
Steroids: lipids that have a 4 ring structure attached to a carbon skeleton.
-Example: cholestrol, hormones
-The picture shown to the left is an example of the testosterone hormone.
*Steroids are a class of lipids (identified by a 4-ring structure, the carbon skeleton, as well as the chemical groups around these rings).
