Macromolecules #3 LIPIDS!!!

Lipids used for long term energy storage all lipids do not dissolve (insoluble) in water (hydrophobic)

4 Kinds of Lipids 1. TRIGLYCERIDE  Most body fat stored in form of triglycerides (adipose tissue in our bodies)  Excellent source of energy – stores more energy than CHO  Helps keep your body warm (insulation)  Women have a thicker layer of fat than men for child bearing

Structure of a Triglyceride: Contains 4 subunits: glycerol + 3 fatty acids Contains 4 subunits: glycerol + 3 fatty acids Glycerol: 3-carbon molecule with a hydroxyl group attached to each carbon atom Glycerol: 3-carbon molecule with a hydroxyl group attached to each carbon atom Fatty acids: long chains of carbon and hydrogen atoms, with a carboxyl group at one end Fatty acids: long chains of carbon and hydrogen atoms, with a carboxyl group at one end Simple triglyceride: all 3 fatty acids are the same Simple triglyceride: all 3 fatty acids are the same In a mixed triglyceride: 3 fatty acids are different In a mixed triglyceride: 3 fatty acids are different

Diagram of A Triglyceride

4 Kinds of Triglycerides cont. 2. FATTY ACIDS:  Long chains of carbon and hydrogen atoms, with a carboxyl group at one end  Can be:  Saturated – contains all single bonds between it’s carbon atoms so chain is straight  E.g. steric acid  Unsaturated – contains at least one double or triple bond between it’s carbon atoms so chain is bent  e.g. oleic acid

Saturated Triglyceride (saturated fats):  Contains fatty acids with only single bonds  Less healthy form of fat  Solid at room temperature  Diets high in saturated fats can lead to clogged arteries which increase risk of heart attack and stroke  e.g. animal fats – used to make lard and fats in butter

Diagram of Saturated Triglyceride

Unsaturated Triglyceride (unsaturated fats):  Contains fatty acids with more than one double bond  Healthier form of fat  Liquid at room temperature  E.g. vegetable oils made from plants such as sunflowers, canolas, olives, grapeseed

Diagram of Unsaturated Triglyceride

4 Kinds of Lipids cont. 3. STEROIDS:  Lipid molecules made of 4 carbon rings e.g.  Male and female sex hormones: testosterone, estrogen, progesterone

Steroid examples continued  CHOLESTEROL: - Steroid found in cell membranes (causes membrane to be “fluid”) - There is no cholesterol in plants - Reducing saturated fats in your diet helps to reduce your blood cholesterol levels - High concentration of cholesterol in blood stream can clog your arteries and increase your risk of heart attack and stroke - HDL – “good cholesterol” - LDL – “bad cholesterol”

Diagram of Cholesterol Molecule

4 Kinds of Lipids cont. 4. PHOSPHOLIPIDS  Main component of cell membranes  Determine what is allowed to enter and leave cell  Lipid molecules similar to triglycerides, but a phosphate group replaces one of the fatty acids  Have a  hydrophilic (water-loving, polar) head  Hydrophobic (water-hating, non-polar) tail

Diagram of Phospholipid:

FLUID MOSAIC MODEL OF CELL MEMBRANE  Represents a structure of the cell membrane which is made of many parts that are free flowing, yet stay together

FMM The Cell Membrane is Composed of: The Cell Membrane is Composed of:  Phospholipid bilayer: hydrophilic on the outside and hydrophobic on the inside  Cholesterol molecules: maintain the fluid condition of the phospholipid bilayer by separating the phospholipid molecules  Embedded proteins:  Integral proteins: span entire width of phospholipid bilayer and act as channels for molecules to pass into and out of the cell  Peripheral proteins: sit on outside membrane and act as recognition receptors for the cell

Recall: Function of Cell Membrane  Separates the cell contents from it’s environment and allows for selective passage of materials in and out of the cell  Substances that:  Can enter cell membrane:  Water and other small molecules  Large, hydrophobic molecules  Cannot enter cell membrane (need to enter through protein channels in membrane):  Large hydrophilic molecules (glucose)  Ions (charged atoms: Na +, Cl -, K +