3D Structure of Testosterone: A Steroid Hormone Example

📚 Quick Study Guide

• 🧬 Testosterone is a steroid hormone belonging to the androgen group.
• 🧪 Its molecular formula is $C_{19}H_{28}O_2$.
• 🔍 The structure consists of four fused carbon rings: three six-membered rings (A, B, and C) and one five-membered ring (D).
• 💡 Key functional groups include a ketone group at C3 and a hydroxyl group at C17.
• 🔬 The 3D shape of testosterone allows it to bind to specific androgen receptors inside cells, triggering various physiological effects.
• 📝 The A ring can be reduced by 5$\alpha$-reductase into Dihydrotestosterone (DHT) which is more potent.

🧪 Practice Quiz

1. Which of the following best describes the basic structure of testosterone?

   1. A) A linear chain of amino acids
   2. B) Four fused carbon rings
   3. C) A double helix structure
   4. D) A single carbon ring

2. What is the molecular formula of testosterone?

   1. A) $C_{18}H_{30}O_3$
   2. B) $C_{19}H_{28}O_2$
   3. C) $C_{20}H_{32}O_2$
   4. D) $C_{17}H_{26}O_3$

3. Which functional group is located at the C3 position of testosterone?

   1. A) Hydroxyl group
   2. B) Carboxyl group
   3. C) Ketone group
   4. D) Amine group

4. Which rings in the testosterone structure are five-membered?

   1. A) Ring A
   2. B) Ring B
   3. C) Ring C
   4. D) Ring D

5. What is the primary role of testosterone's 3D structure?

   1. A) To dissolve in water
   2. B) To bind to specific receptors
   3. C) To provide structural support to cells
   4. D) To transport oxygen

6. What enzyme converts testosterone into DHT?

   1. A) Aromatase
   2. B) 5$\alpha$-reductase
   3. C) Kinase
   4. D) Polymerase

7. How many six-membered carbon rings are present in the testosterone structure?

   1. A) One
   2. B) Two
   3. C) Three
   4. D) Four