1. Molecular Biology LIPIDS

2. Key component in cells  especially in the cell membrane. Made of C, H and O Insoluble in water

3. Foods – fish, olive oil, red meat, nuts. “Fats” are solid at room temperature and liquids at body temperature “Oils” are liquid at room and body temperature

4. Structure: Lipids are made up of two portions: a glycerol head and fatty acid tails. glycerol fatty acids (you need to be able to draw and/or recognize these structures)

5. Triglycerides are formed by condensation from three fatty acids and one glycerol

6. The linkages are called an “ESTER” bond.  -OH on the glycerol (an alcohol)  -COOH on the fatty acid (an acid)

7. Triglycerides are used in energy storage.  released by aerobic cellular respiration They do not conduct heat well  used as insulators

8. 3 functions of lipids: 1. Cell membrane: the main component of cell membranes are phospholipids 2. Energy Storage: lipids provide concentrated long-term energy storage which can release fuel for cellular respiration as needed. 3. Thermal insulators: reduce the loss of heat from an organism (e.g. lipids under the skin).

9. Three important groups of lipids: Phospholipids and triglycerides and waxes 1. Phospholipids are the building blocks of the fluid mosaic model of the cell membrane.  They have a phosphate/glycerol head that is polar and hydrophilic and two fatty acid tails that are hydrophobic. 2. Triglycerides used in long-term energy storage.  These special lipid molecules are built from one glycerol and three fatty acids with the help of an enzyme.

10. 3. Waxes – are the third group of lipids. They are formed from long chains of fatty acids joining long- chain alcohol or carbon rings. Waxes are insoluble in water, and are used for water proofing plant leaves or animal feathers and fur.

11. ENERGY STORAGE Both Carbohydrates and Lipids used for energy storage in humans Lipids used for LONG-TERM storage Stored as “fats” in specialized cells called ADIPOSE TISSUE

12. ENERGY STORAGE Total energy gain 9 Calories/gram. Yield twice as much energy as carbohydrates. 2 types of lipids: saturated and unsaturated

13. Saturated Fats Lipids that are solid or semi-solid at room temperature are said to be saturated (loaded up with covalent bonds to H atoms). E.g. Butter, shortening and marbling in meat. Saturated fats are very stable at room temperature.

14. Unsaturated Fats Lipids that are liquid at room temperature are said to be unsaturated (containing double bonds or less H atoms). E.g. Oil is an example of an unsaturated fat. Unsaturated fats are easier to break down in the body than saturated fats.

15. When an unsaturated fat has only one unsaturated bond, it is known as monounsaturated. When a fat has more than one unsaturated bond it is known as polyunsaturated.

16. Fats and Diet- “ not all fat is bad” Saturated fats - stable fats in the body tend to stay put once ingested leading to plaque in the arteries and ultimately to health complications (e.g. stroke, cancer, high blood pressure, type two diabetes). Cholesterol –Cholesterol is required by the cell membrane and is also important for the production of hormones (specifically sex hormones – estrogen and testosterone). There are two different types of cholesterol in the blood HDL and LDL. HDL is the “good” cholesterol and LDL is the “bad” cholesterol.

17. Unsaturated fatty acids can be cis or trans isomers (2.3)

18. Isomers Compounds with the same chemical formula may differ in the arrangement of their atoms Such variations in the arrangement of atoms = ISOMERS

19. Structural Isomers The atoms are linked in difference sequences Example: fructose and glucose (6 C, 12 H, 6 O)

20. Optical Isomers Identical in every way but are mirror images of each other Example: D-alanine and L-alanine

21. cis and trans isomers Type of isomerism describing the relative orientation of functional groups within a molecule. They exist when the rotation of bonds is greatly restricted  Double-bonds, ring structures

22. cis and trans isomers Trans-fatty acids: the hydrogens are on opposite sides of the 2 carbons that are double bonded. Cis-fatty acids: the hydrogen atoms are on the same side.  nearly always the case in unsaturated fatty acids in living organisms.