13.E: Exercises

Multiple choice

1. What are the building blocks of a phosphoglyceride, specifically phosphatidic acid?
   1. glycerol + 2 phosphate groups + 1 fatty acid
   2. glycerol + 1 phosphate group + 2 fatty acids
   3. glycerol + 1 phosphate group
   4. glycerol + 3 fatty acids
2. Which term does not describe oleic acid?
   1. polyunsaturated
   2. long-chain hydrocarbon
   3. carboxyl group
   4. carbon double bond
3. While growing some cells, you lower the temperature of the culture. What happens immediately to the membrane fluidity?
   1. Nothing happens.
   2. The membrane becomes less fluid.
   3. The membrane becomes more fluid.
   4. The membrane fluidity fluctuates back and forth from high to low.
4. The term amphipathic describes molecules that have ________.
   1. two polar regions
   2. only a single polar region
   3. both a polar and a nonpolar region
   4. no polar regions
5. Which of the following is not a polymer of numerous monomer units?
   1. carbohydrates
   2. proteins
   3. nucleic acids
   4. lipids
6. Triglycerides are composed of three fatty acids attached to a molecule of ________.
   1. glycerol
   2. phosphoric acid
   3. glucose
   4. lipid
7. Lipids are distinct from other macromolecules in that they:
   1. contain both carbon and hydrogen atoms
   2. can have both polar and non-polar components
   3. form large structures without forming covalent bonds
   4. are only found in membranes
8. The “phospho” portion of a phospholipid:
   1. is hydrophobic
   2. is hydrophilic
   3. hydrogen bonds to fatty acid chains
   4. is found on the inside of a membrane bilayer
9. A fatty acid with out carbon-carbon double bonds is considered:
   1. hydrophilic
   2. unsaturated
   3. saturated
   4. amphipathic
10. Which is not an example of a lipid molecule?
    1. beeswax
    2. sphingomyelin
    3. cholesterol
    4. arginine
11. The linkage between fatty acid tails and glycerol is known as an:
    1. ester bond
    2. hydrogen bond
    3. ionic bond
    4. oxygen bond
12. The presence of a “cis” double bond in a fatty acid will cause it to:
    1. undergo a condensation reaction
    2. solidify at higher temperature
    3. pack less tightly with other lipids
    4. act more like a saturated fat
13. Steroids are distinct from other lipids because they:
    1. cannot be found in membranes
    2. contain fused ring structures
    3. are insoluble in water
    4. can have polar functional groups
14. Which of the following statements is true of lipids?
    1. They contain hydrocarbon chains or rings.
    2. Cholesterol is an important phospholipid.
    3. They are more soluble in water than in alcohol.
    4. They are only used as energy-storage molecules.

Warm-up Questions

1-4. Compare the structures of the lipid molecules shown below. Use terms such as polar/nonpolar, saturated/unsaturated, and long-chain/short-chain.

Match the following terms (1-10) to their definitions (A-J)

Intermediate Questions

1. Carbohydrates and lipids contain the same elements (carbon, hydrogen and oxygen) but have very different chemical properties. Explain these differences. This image shows a lipid called cerebroside. Describe its structure.

2. This image shows a lipid called cerebroside. Describe its structure. 

    https://u-helmich.de/bio/lexikon/C/b...rebrodid-1.jpg

3. This image shows a space-filling model of a lipid called linoleic acid. You can access an interactive 3D model of the molecule here. What chemical features are responsible for its structure?

   https://pubchem.ncbi.nlm.nih.gov/compound/5280450

4. What are the two primary ways of packaging cholesterol? What is the purpose of each?

5. How do lipids contribute to energy storage in the body?

6. Why are triglycerides a more efficient energy storage molecule than glycogen?

7. What properties of lipids make them soluble in organic solvents? 

8. What structural features determine the melting point of fatty acids?

Challenge Questions

1. How does the shape of lipid molecules affect membrane fluidity?

2. Steroid hormones such as estrogens travel through the bloodstream while bound to carrier proteins. They are recognized by receptors in the cell cytosol. Based on what you know about lipid structure and function, describe a mechanism for steroid hormone entry into cells. 

Health-Related Questions

1. The image below shows a high-density lipoprotein (HDL) particle, which is part of the body’s system for packaging and transporting cholesterol to the liver. Describe the structure of the HDL particle, noting the type, number and location of lipid and non-lipid components.

    

   https://medlineplus.gov/images/PX000...SENTATION.jpeg

2. How can imbalances in lipoprotein levels such as HDL increase the risk of cardiovascular diseases such as heart attacks and stroke?