Lipids

Lipids Characteristics Lipids are hydrophobic (water fearing) -Because lipids are hydrophobic they are able to create boundaries in aqueous solutions Example: oil and water; cell membrane

Functions of Lipids Stores energy (fats) Chemical signals- steroids (estrogen, testosterone, cortisol, cholesterol) Moderate reproduction, metabolism, blood pressure, stress Acts as boundaries (phospholipids)

FATS

Fats Made of a glycerol backbone attached to 3 fatty acids

Saturated fats Three fatty acids contains the max number of hydrogen bonds Solid at room temp Examples: lard, butter

Unsaturated fats Fatty acids do not have the max number of hydrogen. This is because some of the carbons have bonded together. Examples: fats in fruits, and fish as well as many oils

The terms saturated and unsaturated lipids refer to the number of bonds on each carbon atom that makes up the fatty-acid tail of the molecule. Saturated lipids are so-called because they have single bonds between all the carbon atoms, and therefore all the carbons are bonded to the maximum number of hydrogen atoms. These chains are fairly straight and can pack closely together, making these fats solid at room temperature. Other fats have some double bonds between some of the carbons in the tail, causing the molecule to bend. As carbon atoms with double bonds are not bonded to as many hydrogens as possible, they are called unsaturated fats. The kinks in the tails mean that unsaturated fats can't pack as closely together, making them liquid at room temperature.

Saturated versus Unsaturated Why are saturated fats less healthy than unsaturated? Unsaturated fat molecules are a curved and kinked with negative charges that repel each other so they don't stick together. Because these molecules don't stick together, they flow - both in the food and in the arteries. The molecules of a saturated fat are flat. They pile up like pages in a book and stick to each other. Do you want them to flow like oil or clump together like butter in your body? http://www.askdrsears.com/HTML/4/T041300.asp

STEROIDS

Steroids Unlike the fats carbon chain structure, steroids are in a 4 ring shape Instead of a energy storage compound steroids (examples: cortisol, cholesterol, estrogen & testosterone) send signals throughout the body Cholesterol is a steroid found in your cell and in cell membranes

Cholesterol Cholesterol is required to build and maintain membranes (it regulates membrane fluidity) In its structural role, cholesterol reduces the permeability of the plasma membrane to protons (positive hydrogen ions) and sodium ions Within the cell membrane, cholesterol also functions in intracellular transport, cell signaling and nerve conduction.

PHOSPHOLIPIDS

Creating Boundaries Another important job of lipids is to create boundaries (especially for cell membranes) These lipids are called phospholipids, and they have both a hydrophillic and a hydrophobic end

Computer Activity PHILIA VERSUS PHOBIA Philia- love of Phobia- fear of What do you love? What do you fear? Phobias are named by taking a prefix and putting it in front of –phobia or –phobic. Use the following website to find one thing you love (philia) and one thing you are afraid of (phobia) Using the prefix write down the name of your philia and phobia http://www.phobialist.com/

Lab Activity PHAT LAB The figure to the left depicts a phospholipid. Notice that the head of the phospholipid is made of a phosphate group and the tail is made of hydrocarbon chains. In lab we will determine whether the head or tail of a phospholipid is hydrophobic

Does carbon like water or hate it?? HEADS OR TAILS?? Head- made of a phosphate group Tail- made of a hydrocarbon IT’S THE CARBON!!! Does carbon like water or hate it??

Lipid review Lipid characteristics - organic - hydrophobic Lipid functions: - act as boundaries - act as chemical signals - store energy in your body