1. LIPIDS : FRIENDS OR FOES? What are lipids? What are lipids? Characteristics Characteristics What are lipids for? What are lipids for? Fats and oils Fats and oils Other types of lipids Other types of lipids

2. WHAT ARE LIPIDS? Lipids are a heterogenous group of substances formed: by fatty acids and glycerol as in the case of fats and oils, by fatty acids and glycerol as in the case of fats and oils, by steroids (cholesterol derivatives) as in the case of steroid hormones and some vitamins, or by steroids (cholesterol derivatives) as in the case of steroid hormones and some vitamins, or by terpenes (another type of complex molecules, as in plant pigments and scents. by terpenes (another type of complex molecules, as in plant pigments and scents.

3. EXAMPLES OF LIPIDS FATS AND OILS FATS AND OILS WAXES WAXES STEROID HORMONES SUCH AS THE SEXUAL HORMONES (OESTROGEN AND TESTOSTERONE) STEROID HORMONES SUCH AS THE SEXUAL HORMONES (OESTROGEN AND TESTOSTERONE) CERTAIN PLANT PIGMENTS AND SCENTS CERTAIN PLANT PIGMENTS AND SCENTS PHOSPHOLIPIDS AND SPHYNGOLIPIDS PHOSPHOLIPIDS AND SPHYNGOLIPIDS

4. CHARACTERISTICS OF LIPIDS Lipids are insoluble in water (so they are non-polar). Lipids are insoluble in water (so they are non-polar). Lipids are soluble in organic, non-polar solvents. Lipids are soluble in organic, non-polar solvents. Lipids are large, complex molecules. Lipids are large, complex molecules. Lipids can store and then release a lot of energy when broken down (fats store 37 kJ/g compared to 17 kJ/g in carbohydrates). Lipids can store and then release a lot of energy when broken down (fats store 37 kJ/g compared to 17 kJ/g in carbohydrates). Lipids can combine with other types of molecules such as sugars and proteins to form glycolipids or lipoproteins. Lipids can combine with other types of molecules such as sugars and proteins to form glycolipids or lipoproteins.

5. WHAT ARE LIPIDS FOR? In living organisms lipids are used: As a long-term energy source. As a long-term energy source. To help bouying in aquatic large animals. To help bouying in aquatic large animals. As a heat insulator (blubber). As a heat insulator (blubber). As a barrier (as in cell membranes). As a barrier (as in cell membranes). As a waterproof substance or extra protection layer (waxes in plants, skin or feathers). As a waterproof substance or extra protection layer (waxes in plants, skin or feathers). Some form sex hormones and vitamins (D). Some form sex hormones and vitamins (D).

6. THE BAD & GOOD GUYS: FATS AND OILS Fats and oils are made of two types of molecules: glycerol and fatty acids. Fats and oils are made of two types of molecules: glycerol and fatty acids. glycerol glycerol

7. FATTY ACIDS Fatty acids are very long chains of carbon and hydrogen atoms and an acid group atone end. They come in two flavours: saturated and unsaturated. Fatty acids are very long chains of carbon and hydrogen atoms and an acid group atone end. They come in two flavours: saturated and unsaturated. Saturated fatty acids have single bonds between C atoms. Saturated fatty acids have single bonds between C atoms. Unsaturated fatty acids have at least one double bond between C atoms. Unsaturated fatty acids have at least one double bond between C atoms.

8. Characteristics of saturated and unsaturated fatty acids Saturated fatty acids are linear, straight and rigid molecules so they are solid at room temperature (20ºC). Saturated fatty acids are linear, straight and rigid molecules so they are solid at room temperature (20ºC). Unsaturated fatty acids bend where the double bond is, so the molecules are more flexible and liquid at room temperature (20ºC). Unsaturated fatty acids bend where the double bond is, so the molecules are more flexible and liquid at room temperature (20ºC).

10. Sources of saturated and unsaturated fatty acids: fats and oils Sources of saturated and unsaturated fatty acids: fats and oils

11. Making friends: the ester bond Fats and oils are triglycerides: Fats and oils are triglycerides: 3 fatty acids + glycerol triglyceride + 3 H 2 O 3 fatty acids + glycerol triglyceride + 3 H 2 O

12. The famous Cholesterol Cholesterol is a series of 5 rings and a side hydrocarbon chain made by all cells as it forms part of the cell membrane, some hormones and vitamins. Cells manufacture almost 1 g/day according to needs. Cholesterol is a series of 5 rings and a side hydrocarbon chain made by all cells as it forms part of the cell membrane, some hormones and vitamins. Cells manufacture almost 1 g/day according to needs.

14. Danger! The trans fats Trans fats are oils (unsaturated triglycerides) that have been chemically modified to partially hydrogenate them. In this way a liquid substance becomes more solid and easily manageable by the food industry. But in the process, the atoms of H are in a different position (opposed to each other) when the C-C is formed. This makes the molecule more sticky and prone to clog arteries.

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