Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

10. Lipids

Steroids

Biochemistry

10. Lipids

Steroids

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Multiple Choice

All steroids contain which of the following?

A fused four-ring structure known as the cyclopentanoperhydrophenanthrene nucleus

A benzene ring as the core structure

A long hydrocarbon chain with a terminal carboxyl group

A peptide backbone with alternating D- and L-amino acids

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Verified step by step guidance

Understand the definition of steroids: Steroids are a class of lipids characterized by a specific structural framework. They are derived from a common precursor molecule, cholesterol, and play various roles in biological systems, such as hormones and signaling molecules.

Identify the structural feature common to all steroids: All steroids share a core structure known as the cyclopentanoperhydrophenanthrene nucleus. This is a fused four-ring system consisting of three six-membered rings (A, B, and C) and one five-membered ring (D).

Analyze the options provided: Compare the structural features described in the options to the known characteristics of steroids. For example, a benzene ring, a long hydrocarbon chain with a terminal carboxyl group, and a peptide backbone are not characteristic of steroids.

Focus on the correct option: The cyclopentanoperhydrophenanthrene nucleus is the defining structural feature of steroids. This fused ring system is present in all steroid molecules, distinguishing them from other classes of biomolecules.

Conclude the reasoning: Based on the structural analysis, the correct answer is the fused four-ring structure known as the cyclopentanoperhydrophenanthrene nucleus, as it is the hallmark of all steroids.