Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

2. Cell Chemistry & Cell Components

Lipids

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Lipids

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Problem 15

Textbook Question

Compare and contrast the structures of phospholipids and triglycerides.

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Phospholipids and triglycerides are both types of lipids, but they differ in their structure and function. Begin by identifying the basic building blocks of each molecule. Both are composed of glycerol and fatty acids, but their arrangements differ.

For triglycerides, note that they consist of one glycerol molecule bonded to three fatty acid chains. This structure is formed through ester bonds created during a dehydration synthesis reaction.

For phospholipids, explain that they consist of one glycerol molecule, two fatty acid chains, and a phosphate group. The phosphate group often has an additional polar molecule attached, making the head hydrophilic (water-attracting).

Compare the hydrophobic and hydrophilic properties of each molecule. Triglycerides are entirely hydrophobic due to their nonpolar fatty acid chains, while phospholipids have a hydrophilic head (phosphate group) and hydrophobic tails (fatty acids), making them amphipathic.

Conclude by discussing the functional implications of their structures. Triglycerides are primarily used for long-term energy storage, while phospholipids are key components of cell membranes, forming bilayers due to their amphipathic nature.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Phospholipid Structure

Phospholipids are composed of a glycerol backbone, two fatty acid tails, and a phosphate group. The hydrophilic (water-attracting) phosphate head interacts with water, while the hydrophobic (water-repelling) fatty acid tails avoid water. This unique structure allows phospholipids to form bilayers, which are fundamental to cell membranes, creating a barrier that separates the interior of the cell from the external environment.

Triglyceride Structure

Triglycerides consist of a glycerol molecule bonded to three fatty acid chains. Unlike phospholipids, triglycerides are entirely hydrophobic due to their long fatty acid tails, making them efficient for energy storage. They are the main form of stored energy in animals and plants, and their structure allows them to pack tightly, providing a dense energy source.

Functional Differences

The structural differences between phospholipids and triglycerides lead to distinct functions. Phospholipids are crucial for forming cellular membranes, providing structural integrity and fluidity, while triglycerides serve primarily as energy reserves. This functional divergence is essential for understanding how these lipids contribute to biological processes and cellular organization.

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Unsaturated fatsa. have double bonds in their fatty acid chains.b. have fewer fatty acid molecules per fat molecule.c. are associated with greater health risks than are saturated fats.d. are more common in animals than in plants.

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Which of the following substances is a major component of the cell membrane of a fungus?a. celluloseb. chitinc. cholesterold. phospholipids

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A fat molecule consists of .a. carbohydrates and proteins;b. complex carbohydrates only;c. saturated oxygen atoms;d. a carbon skeleton and fatty acids

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Textbook Question

Another aspect of the Nurses' Health Study looked at the percentage of change in the risk of coronary heart disease associated with substituting one dietary component for another. These results estimated that replacement of 5% of energy from saturated fat in the diet with unsaturated fats would reduce the risk of heart disease by 42%, and that the replacement of 2% of energy from trans fat with unsaturated fats would reduce the risk by 53%. Explain what these numbers mean.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Lipids contain oxygen and are therefore polar covalent compounds.

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Textbook Question

Considering that water is a main component of the juices in the stomach and intestines, explain why digestion of lipids is more complicated than digestion of carbohydrates and proteins.

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Textbook Question

Explain why monosaccharides are polar and fatty acids are nonpolar even though they both contain the same atoms.

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Multiple Choice

Which type of macromolecule stores energy and provides thermal insulation for the body?

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