The Watson’s Crick double helix model of DNA is
**Core Concept**
The Watson-Crick double helix model of DNA is based on the **double-stranded helix** structure, where two complementary strands of DNA are twisted together. This model explains the **molecular structure** of DNA, which is essential for understanding genetic inheritance and expression. The **double helix** structure is stabilized by **hydrogen bonds** between the bases.
**Why the Correct Answer is Right**
Although the exact correct answer choice is not provided, the Watson-Crick model is characterized by its **right-handed double helix** structure, with **sugar-phosphate backbones** on the outside and **base pairs** on the inside. The base pairs are formed by **adenine** and **thymine**, and **guanine** and **cytosine**, through **hydrogen bonding**. This structure allows for **efficient replication** and **transcription** of genetic information.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because the Watson-Crick model does not describe a single-stranded structure.
**Option B:** This choice is incorrect because the Watson-Crick model does not describe a left-handed double helix.
**Option C:** This choice is incorrect because the Watson-Crick model does describe a right-handed double helix, not the other way around.
**Clinical Pearl / High-Yield Fact**
The Watson-Crick double helix model is crucial for understanding **genetic diseases** and **cancer**, as it provides a framework for understanding **mutations** and **genetic variations**. Remember that the **double helix** structure is essential for **DNA replication** and **transcription**.
**Correct Answer:** Correct Answer: D. Right-handed double helix