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Lipids- Does this molecule make me look fat? A.P. Biology Chapter 3 Liberty Senior High School Mr. Knowles.

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Presentation on theme: "Lipids- Does this molecule make me look fat? A.P. Biology Chapter 3 Liberty Senior High School Mr. Knowles."— Presentation transcript:

1 Lipids- Does this molecule make me look fat? A.P. Biology Chapter 3 Liberty Senior High School Mr. Knowles

2 Lipids Have C, H, O, but more H and less O than carbohydrates. Four Kinds: Fats, Phospholipids, Terpenes, Steroids Functions of Lipids: 1. May form cell membranes. 2. Used for long- term energy storage.


4 1. Fats A Fat = Glycerol + 1 or more Fatty Acids Glycerol- a 3 carbon alcohol. Fatty Acid- HO - C - R O Where R = hydrocarbon chain.

5 Synthesis of a Fat Dehydration Synthesis - removing H 2 O and forming an ester bond between the OH of glycerol and the carboxyl group of a fatty acid.

6 Fats: are constructed from two types of smaller molecules, a single glycerol and usually three fatty acids. (b) Fat molecule (triacylglycerol) H H H H H H H H H H H H H H H H O Figure 5.11

7 A Glycerol Three Fatty Acids

8 Types of Fatty Acids Saturated Fatty Acids- single-bonded hydrocarbon chains completely filled with H. Solids at Room Temp. Usually from animals. Ex. Lard Unsaturated Fatty Acids- usually contain a double bond within the hydrocarbon chain, at least one carbon may bond with a H. Liquids at room temp. Derived from plants. Ex. Veg. Oil

9 Saturated Fatty Acids: -have the maximum number of hydrogen atoms possible. -have no double bonds. (a) Saturated fat and fatty acid Stearic acid Figure 5.12

10 Unsaturated Fatty Acids: –Have one or more double bonds. (b) Unsaturated fat and fatty acid cis double bond causes bending Oleic acid Figure 5.12


12 Steric Acid- a saturated fatty acid.

13 Show me oleic acid- an unsaturated fatty acid.

14 What does an unsaturated fat look like?

15 How does olestra compare to real fats?

16 So what is Peanut Butter? If it comes from a plant, it should be a(n)…. Unsaturated Fat! But it’s a solid! It is a hydrogenated fat!

17 The Importance of Fats Efficient energy-storage molecules because of high # of C-H bonds. More than twice the # in carbos. Convert unused glucose into starch or fats. Fats = 9 kcal/g; Carbo = 4 kcal/g Energy in Saturated fats > Unsaturated fats

18 So what does this mean for living organisms? The Big Picture! Show the movie! Discovery Channel- Grizzly: Face to Face

19 The Importance of Lipids for Survival Video: Discovery- Blue Planet: Frozen Seas

20 2. Phospholipids Substitute a phosphate (PO 4 ) for one fatty acid in a triglyceride. The (PO 4 ) group is polar (charged). The polar ends interact with each other- Hydrophilic The nonpolar (uncharged) hydrocarbon chains interact- Hydrophobic Found in all cell membranes.

21 Phospholipid structure: –Consists of a hydrophilic “head” and hydrophobic “tails.” CH 2 O P O O O CH CH 2 OO C O C O Phosphate Glycerol (a) Structural formula (b) Space-filling model Fatty acids (c) Phospholipid symbol Hydrophobic tails Hydrophilic head Hydrophobic tails – Hydrophilic head CH 2 Choline + Figure 5.13 N(CH 3 ) 3

22 Phospholipids

23 A Phospholipid

24 A spontaneous barrier?

25 Micelles

26 The structure of phospholipids: –Results in a bilayer arrangement found in cell membranes. Hydrophilic heads WATER Hydrophobic tails Figure 5.14

27 Phospholipids form a lipid bilayer for cell membranes

28 Phospholipid Bilayer


30 Phospholipid Bilayers are 3-Dimensional!

31 The lipid bilayer allows nonpolar molecules to freely enter cells- “like dissolves like.”

32 3. Terpenes Long chain lipids; many CH bonds. Many photosynthetic pigments are terpenes. Examples are the cholorophyls and carotenes. Rubber is a terpene.


34 4. Steroids and other ringed lipids Four-ringed Structures. Ex. Cholesterol, hormones, vitamin D Animal cell membranes contain cholesterol, most bacteria do not.

35 Steroids

36 Who cares? How does all of this relate to biology?

37 Lipids are Effective Barriers At the cellular level – phospholipids. A waxy covering on the epidermis of plants – cutin. Coating of bird wings – oils.

38 Other Importants Fats provide a way of absorbing and storing fat- soluble vitamins A, D, E, K.

39 DDT: a fat-soluble poison and the osprey

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