All About Lipids

1. All About Lipids

2. Basic Details • Lipids are a diverse group of molecules made of carbon, hydrogen and oxygen atoms • Lipids are hydrophobic (they do not dissolve in water) • The structure of a lipid is usually made of 2 parts: • 1. A glycerol molecule and • 2. One or more fatty acid tails • Common examples of lipids are fats, oils and waxes.

3. Basic Details Glycerol Molecule Fatty Acid tails

4. Saturated, Unsaturated and Polyunsaturated • Lipids can be saturated, unsaturated or polyunsaturated depending on whether or not they have any double bonds between the carbon atoms in the fatty acid chains. • Saturated = no carbon-carbon double bonds • Unsaturated = ONE carbon-carbon double bond; you will sometimes see these lipids called monounsaturated lipids. • Polyunsaturated = more than one carbon-carbon double bond

5. Saturated, Unsaturated and Polyunsaturated Saturated Unsaturated Polyunsaturated

6. Common Examples • Saturated lipids = Butter, Crisco, margarine (saturated lipids are usually soft solids at room temperature) • Unsaturated lipids = Olive oil and the fats found in avocados and nuts (unsaturated lipids tend to be liquids at room temperature) • Polyunsaturated lipids = Corn oil, sesame oil, canola oil and peanut oil (polyunsaturated lipids also tend to be liquids at room temperature)

7. Common Examples • A diet rich in saturated fats can lead to a heart disease known as atherosclerosis. This disease results from the buildup of saturated fats inside the walls of your blood vessels. • These deposits are known as plaques. They cause your blood vessels to narrow so that blood cannot easily flow and in extreme cases can result in heart attacks and death.

8. Common Examples • However, not all lipids are bad for you! In fact, some of them are essential to good nutrition and we have to eat them because our body can’t produce them. These lipids are unsaturated and they’re called omega-3 fatty acids. These are found in fish and nuts.

9. Functions of Lipids #1 1. Lipids can be used to store energy. A gram of fat stores twice as much energy as a gram of carbohydrate. Humans store excess calories as fat so that it can be converted to energy at a future time, if needed. • Humans and other mammals store our fat in cells called adipose cells which swell and shrink as fat is deposited or used up. • Adipose tissue (fat) also serves to cushion our vital organs and keep them safe and it helps regulate our body temperature by keeping us warm. • Mammals such as whales, seals and other marine mammals have a thick layer of fat, called blubber, that helps to protect them in cold ocean water.

10. Functions of Lipids #2 2. Lipids make up the main structural component in cell membranes. • These lipids are called phospholipids. • They have a hydrophilic head and a hydrophobic tail. • Cell membranes have a phospholipid bilayer (this means it has two layers of lipids with the hydrophilic heads on the outside and the hydrophobic tails on the inside of the membrane.

11. Functions of Lipids #3 3. Steroids are lipids. Steroids are chemical messengers in your body. Cholesterol is a lipid and all the other steroids are made from cholesterol.

12. Functions of Lipids #3 • Two common steroids are the sex steroids estrogen and testosterone. • Estrogen is the steroid hormone that is responsible for female development of secondary sex characteristics like breasts and curvy hips. • Testosterone is the steroid hormone responsible for the development of male secondary sex characteristics like a deep voice, facial and chest hair.

13. Answer these questions on the back of your notes paper.Yes, it is for a grade!

14. Are lipids hydrophobic or hydrophilic? • What are the 2 parts of a lipid molecule? • What’s the difference between a saturated lipid, an unsaturated lipid and a polyunsaturated lipid? • What kind of lipid is usually a solid at room temperature? • What heart disease results from the buildup of plaques in artery walls?

15. Are all lipids bad for you? • Does a gram of fat store more energy or less energy than a gram of carbohydrate? • What is the thick layer of fat on marine mammals called? • What kind of lipid is found in cell membranes? • Look at the estrogen and testosterone molecules on the last page of the notes. How are they different?

16. Answers • The majority of lipids are hydrophobic. • A glycerol molecule and a fatty acid tail (also called a fatty acid chain) • A saturated lipid has NO carbon-carbon double bonds. An unsaturated lipid has ONE carbon-carbon double bond. A polyunsaturated lipid has MORE THAN ONE carbon-carbon double bond.

17. Saturated, Unsaturated and Polyunsaturated Saturated Unsaturated Polyunsaturated

18. Answers • Saturated lipids are soft solids at room temperature. • Atherosclerosis • No • More energy (twice as much!) • Blubber • Phospholipids

19. 10. 1 double bond in the ring and a double bonded oxygen on the side 3 double bonds in the ring and an –OH group bonded to it.

20. Copy this list on the back of your 1st page of your notes. Look them up and write a few words describing them. • Atherosclerosis (p.949) • Plaques (p.949) • Omega-3 fatty acids • Adipose • Blubber • Phospholipids • Estrogen • Testosterone

21. Key Words • Atherosclerosis: a heart disease caused by fat that hardens in blood vessels. • Plaques: what forms when fat hardens in blood vessels • Omega-3 fatty acids: a healthy lipid found in fish and nuts • Adipose: human fat tissue

22. Key Words • Blubber: thick layer of fat found on marine mammals like seals and whales • Phospholipid: the lipid that makes up cell membranes • Estrogen: the female steroid hormone • Testosterone: the male steroid hormone