DNA strands have

Options

A. Quaternary structure
B. Same polarity
C. Antiparallel polarity
D. Disulphide bonds.

Answer

To answer the question "DNA strands have what type of structure?", we can break it down into the following steps:

### Step 1: Understand the Structure of DNA
DNA (Deoxyribonucleic Acid) is known for its double helix structure, which consists of two strands that wrap around each other. Each strand is made up of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base.

**Hint:** Remember that DNA is often described as a twisted ladder or a spiral staircase.

### Step 2: Identify the Polarity of DNA Strands
Each DNA strand has a directionality defined by its ends. One end is referred to as the 5' end (five prime) and the other as the 3' end (three prime).

**Hint:** Think of the 5' and 3' ends as the starting and ending points of the DNA strand.

### Step 3: Determine the Orientation of the Strands
In a double helix, the two strands run in opposite directions. This means that if one strand runs from 5' to 3', the other strand runs from 3' to 5'. This orientation is referred to as "anti-parallel."

**Hint:** Visualize the two strands as arrows pointing in opposite directions.

### Step 4: Evaluate the Given Options
Now, let's evaluate the options provided in the question:
- **Quaternary structure:** Incorrect, as DNA is a double helix and does not have a quaternary structure.
- **Same polarity:** Incorrect, as the strands have opposite polarities.
- **Anti-parallel polarity:** Correct, as the strands run in opposite directions.
- **Disulfide bonds:** Incorrect, as DNA does not have disulfide bonds.

**Hint:** Focus on the unique feature of DNA that distinguishes it from other structures.

### Step 5: Conclusion
The correct answer to the question is that DNA strands have "anti-parallel polarity." This means that the two strands of DNA run in opposite directions relative to each other.

**Final Answer:** DNA strands have anti-parallel polarity.