Steroids Overview Quiz
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Questions and Answers

What is a steroid?

An organic compound with four rings arranged in a specific molecular configuration.

The steroid core structure is composed of _____ carbon atoms, bonded in four 'fused' rings.

seventeen

Which ring structure is present in steroids?

  • Cyclooctane
  • Cyclopentano phenanthrene (correct)
  • Cyclopentane
  • Cyclohexane

Cholesterol is the only known steroid found in animals.

<p>False (B)</p> Signup and view all the answers

What is the significance of the aromatic ring with C-3 OH in steroids?

<p>It is essential for activity.</p> Signup and view all the answers

What is the role of modifications at the 16 and 17 positions in steroids?

<p>They enhance activity (D)</p> Signup and view all the answers

What are the common examples of estrogens?

<p>Estrone, estradiol, estriol</p> Signup and view all the answers

Match the steroid with its category:

<p>Testosterone = Androgens Progesterone = Pregnane Cortisol = Corticosteroids Cholesterol = Cholestane</p> Signup and view all the answers

The side chain of steroids can be found at the _____ position.

<p>17th</p> Signup and view all the answers

What is the significance of the six asymmetric carbon atoms in steroids?

<p>They allow for the existence of 64 optically active forms.</p> Signup and view all the answers

Steroids contain fatty acids.

<p>False (B)</p> Signup and view all the answers

Study Notes

Steroids

  • Steroids are organic compounds characterized by four rings arranged in a specific molecular configuration, known as the cyclopentanoperhydrophenanthrene nucleus.
  • The four rings consist of three six-member cyclohexane rings (A, B, and C) and one five-member cyclopentane ring (D).
  • Steroids are distinguished by the functional groups attached to this core structure and the oxidation state of the rings.

Numbering of Steroids

  • The steroid core structure comprises 17 carbon atoms bonded in four fused rings.
  • Angular methyl groups are typically found at C-10 and C-13 positions.
  • An alkyl group may be present at C-17. Sterols typically have a hydroxyl group at C-3.
  • A side chain is attached at the 17th position.

Properties of Steroids

  • Steroids exhibit a relatively flat and rigid molecular structure.
  • They possess high crystalline properties.
  • Steroids are both hydrophilic and lipophilic.
  • They do not contain fatty acids.
  • Cholesterol, a well-known steroid, is exclusively found in animals.

SAR of Steroids

  • The aromatic ring with a C-3 hydroxyl group is essential for activity.
  • The 17β-hydroxyl group, maintaining a constant distance from the 3-OH, is crucial for activity.
  • Unsaturation of ring B reduces activity.
  • Modifications at the 16th and 17th positions can enhance activity.

Nomenclature of Steroids

  • Steroids are primarily named as derivatives of basic steroidal ring systems.
  • These ring systems are categorized based on the number of carbon atoms they contain:
    • Gonane (C17):
    • Estrane (C18): Examples include estrogens (estradiol, estrone, estriol).
    • Androstane (C19): Examples include androgens (testosterone).
    • Pregnane (C21): Examples include progesterone and corticosteroids.
    • Cholane (C24): Examples include bile acids.
    • Cholestane (C27): Examples include cholesterol.

Configuration of Steroids

  • β Configuration: Substituents attached to the ring system from above are designated as β, with lines represented as thickened.
  • α Configuration: Substituents attached to the ring system from below are designated as α, with lines represented as broken or dotted.
  • Unknown Configuration: If the configuration of the substituent is unknown, it is represented with a wavy line.

Stereochemistry of Steroids

  • The stereochemistry of the rings significantly influences the biological activity of specific steroid classes.
  • The steroid nucleus contains six asymmetric carbon atoms (5, 8, 9, 10, 13, 14), potentially leading to 64 optically active forms.
  • Steroids can exist in two conformations: chair form and boat form.

Notable Steroids:

  • Estrogens:

    • Estrone
    • Estradiol
    • Estriol
    • All derived from the Estrane ring system.
    • C18
  • Androgens:

    • Testosterone
    • Derived from the Androstane ring system.
    • C19
    • Androst-4-en-17β-ol-3-one
  • Progesterone:

    • Derived from the Pregnane ring system.
    • C21
    • Progest-4-en-3,20-dione
  • Cortisone:

    • Derived from the Pregnane ring system.
    • C21
    • 17α,21-dihydroxypregn-4-en-3,11,20-trione
  • Bile acid-cholic acid:

    • Derived from the Cholane ring system.
    • C24
    • 3,7,12-Trihydroxycholan-24-oic acid
  • Cholesterol:

    • Derived from the Cholestane ring system.
    • C27
    • Choles-5-en-3β-ol

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Description

Test your knowledge about steroids, their structures, and properties. This quiz covers the chemical configuration, numbering of carbon atoms, and characteristics of steroids, including well-known examples like cholesterol. Perfect for students of biology and biochemistry!

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