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 L2.3

Textbook Question

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

Verified step by step guidance

Monosaccharides are polar because they contain multiple hydroxyl (-OH) groups, which are highly electronegative. These groups create regions of partial negative and positive charges, allowing monosaccharides to form hydrogen bonds with water molecules, making them hydrophilic (water-soluble).

Fatty acids, on the other hand, have a long hydrocarbon chain that is composed of nonpolar covalent bonds between carbon and hydrogen atoms. These bonds do not create significant charge separation, making the hydrocarbon chain hydrophobic (water-insoluble).

Although both monosaccharides and fatty acids contain carbon, hydrogen, and oxygen atoms, the arrangement and type of bonds differ. Monosaccharides have a higher proportion of polar functional groups (e.g., hydroxyl groups), while fatty acids have a dominant nonpolar hydrocarbon chain.

The carboxyl group (-COOH) at the end of a fatty acid is polar, but its effect is overshadowed by the long nonpolar hydrocarbon chain, making the overall molecule nonpolar.

In summary, the polarity of a molecule depends on the distribution of polar and nonpolar bonds. Monosaccharides are polar due to their hydroxyl groups, while fatty acids are nonpolar because of their extensive hydrocarbon chains.

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Key Concepts

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

Polarity

Polarity refers to the distribution of electrical charge around atoms, molecules, or chemical groups. A molecule is considered polar if it has a significant difference in electronegativity between its atoms, leading to a partial positive charge on one end and a partial negative charge on the other. This uneven distribution allows polar molecules, like monosaccharides, to interact with water and other polar substances, making them soluble.

Hydrophilicity vs. Hydrophobicity

Hydrophilicity describes the tendency of a substance to interact favorably with water, while hydrophobicity refers to the tendency to repel water. Monosaccharides, being polar, are hydrophilic and readily dissolve in water. In contrast, fatty acids, despite containing similar atoms, have long hydrocarbon chains that are nonpolar, making them hydrophobic and less soluble in water.

Molecular Structure and Functional Groups

The molecular structure and the presence of functional groups significantly influence a molecule's polarity. Monosaccharides contain hydroxyl (-OH) groups that enhance their polarity, while fatty acids have long hydrocarbon tails with a carboxyl (-COOH) group at one end. The hydrocarbon tail is nonpolar, overshadowing the polar nature of the carboxyl group, resulting in an overall nonpolar character for fatty acids.

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Related Practice

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

Compare and contrast the structures of phospholipids and triglycerides.

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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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Multiple Choice

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

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Multiple Choice

A fat molecule typically contains how many fatty acids?

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Multiple Choice

Which of the following is not a function of lipids in the body?