LIPIDS L 2 BIOLOGY What are Lipids Lipids

LIPIDS L 2 BIOLOGY

What are Lipids? • Lipids include fats, oils and waxes

What is a calorie? • Is it only something to do with fats? • It is a way of measuring the energy content of foods. • The amount of heat needed to raise the temperature of one gram of water by one degree Celsius.

Lipid Composition • Carbon, Hydrogen and Oxygen • Is this similar to one other bio-molecule you have learned about?

LIPID STRUCTURE

Triglycerides • Triglycerides are typical lipids • Composed of one glycerol and three fatty acids.

LIPID

GLYCEROL How many carbon atoms do you see? Oxygen? Hydrogen?

FATTY ACIDS – Two types…

Two Types of Fatty Acid • SATURATED – The fatty acids are all single bonds between Carbon atoms so they are completely full of hydrogen atoms (no double bonds!) • UNSATURATED – There are one or more double bonds between the Carbon atoms.

FATTY ACIDS

SATURATED FATS – Usually solid, fully hydrogenated – animal sources

• UNSATURATED FAT – Usually a liquid; not fully hydrogenated plant sources

Trans-Fats • What have you heard about these?

Lipid Functions • Major component of cell membranes. • Long term energy storage. • Protection/ waterproofing.

The Skinny on Fat Read the first three paragraphs make margin notes and/or underline anything that you think is most important. Does anything surprise you about what you read?

Does dietary fat cause weight gain? 1. Would a completely fat free diet be healthy? Give examples to support your answer. 2. How does the typical American diet compare to recommended guidelines in terms of fat consumption? 3. What factors other than dietary fat play a role in weight gain?

Good Fats vs. Bad Fats 4. Which groups of fats are considered good? Explain why. 5. Which foods contain more omega-3 fats? Why are they considered good fats? 6. Which foods contain monounsaturated fats?

Bad Fats 7. What are the two types of bad fats? Where are they found (food sources)? 8. What are three problems associated with these fats?

Bad Fats continued 9. Trans-fats are used extensively in what kinds of products? 10. Since this article was written, a number of cities have banned the use of artificial trans-fats in restaurants and many companies have begun removing them from their products, why do you think this is?