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Introduction to the lesson
Lipids are very important molecules in biology, especially for storage. In this lesson, we will learn about the structure of lipids and how this structure gives lipids the necessary properties to be good for storage and all their other purposes. Lipids are synthesized in the mitochondria and smooth ER. In the human body, they are stored particularly below the dermis of the skin and around the kidneys.
Introduction to lipids
Read the section under the heading "Lipids" on p.36 of your text book.
Learning Activity 1
Answer the following questions in your exercise book.
- What is one property all lipids share?
- What are the most familiar lipids?
- What is a true lipid?
Fatty Acids
Read the section under the heading "Fatty acids" in your text book (p.36-37)
Learning Activity 2
Answer the following questions in your exercise book.
- What carboxyl group is found in fatty acids?
- What are the two main parts of a fatty acid?
- Draw the two fatty acids shown in Fig. 2.11 (p.34). Can you see the difference between them?
- What does it mean if a fatty acid is "unsaturated"?
- Are fats saturated or unsaturated? Oils?
Alcohols and esters
Read the section under the heading "Alcohols and esters" in your text book (p.37).
Learning Activity 3
Answer the following questions in your exercise book.
- What is the most prominent characteristic of an alcohol?
- Which two groups to react to produce an ester?
- What is an ester bond?
- Draw the reaction that forms an ester. What is this reaction called? What is the reverse reaction?
Triglycerides
Read the section under the heading "Triglycerides" in your text book (p.37-38)
Learning Activity 4
Answer the following questions in your exercise book.
- What is a glyceride?
- How is a triglyceride formed? Draw the reaction. What kind of reaction is this?
- Are triglycerides hydrophillic or hydrophobic?
- What is the main use of triglycerides?
- What are some other uses?
- Explain how the desert kangaroo rat can survive without ever drinking water? Include in your explanation, a drawing of the reaction which produces metabolic water.
Phospholipids
Read the section under the heading "Phospholipids" in your text book (p.38).
Learning Activity 5
Answer the following questions in your exercise book.
- What is unusual about phospholipids?
- Which group in the phospholipid is hydrophillic?
- Considering that phospholipids are the main component of cell surface membrane, can you think why this hydrophobic/hydrophillic property could be useful?
Testing for the presence of lipids
Read Box 2.3 "Testing for the presence of lipids" on p.38 of your text book.
Learning Activity 6
Explain how to test for the presence of lipids.
Definitions and review
Definitions
- Lipid
- Alcohol
- Ester
- Hydrocarbon tail
- Unsaturated lipid
- Polyunsaturated lipid
- Monounsaturated lipid
- Fat
- Oil
- Glyceride
- Triglyceride
- Phospholipid
- Emulsion
Mindmap
Add this section to your chapter two mindmap.