Which type of bond is not present in DNA :-

Options

A. Phosphodiester bond
B. Glycosidic bond
C. Hydrogen bond
D. Disulphide bond

Answer

To determine which type of bond is not present in DNA, we can analyze the types of bonds that are typically found in the structure of DNA. Here’s a step-by-step solution:

### Step 1: Understand the Structure of DNA
DNA, or deoxyribonucleic acid, is a molecule that carries genetic information. It is composed of two strands that form a double helix structure. Each strand is made up of repeating units called nucleotides.

**Hint:** Recall that DNA is a double-stranded molecule made of nucleotides.

### Step 2: Identify Components of a Nucleotide
A nucleotide consists of three main components:
1. A deoxyribose sugar
2. A phosphate group
3. A nitrogenous base (adenine, thymine, cytosine, or guanine)

**Hint:** Remember the three parts of a nucleotide and how they connect to form DNA.

### Step 3: Identify the Types of Bonds in DNA
1. **Phosphodiester Bond**: This bond connects the phosphate group of one nucleotide to the sugar of the next nucleotide, forming the backbone of the DNA strand.
2. **Glycosidic Bond**: This bond connects the deoxyribose sugar to the nitrogenous base in each nucleotide.
3. **Hydrogen Bond**: These bonds form between complementary nitrogenous bases on opposite strands (A-T and C-G pairs), holding the two strands together.

**Hint:** Think about how the components of nucleotides are linked together and how strands are held together.

### Step 4: Identify the Bond Not Present in DNA
The question asks for the type of bond that is not present in DNA. The options provided are:
- Phosphodiester bond
- Glycosidic bond
- Hydrogen bond
- Disulfide bond

Among these, the **disulfide bond** is not present in DNA. Disulfide bonds are covalent bonds that typically occur between cysteine residues in proteins, not in nucleic acids like DNA.

**Hint:** Consider which of the listed bonds are typically associated with proteins rather than nucleic acids.

### Conclusion
The type of bond that is not present in DNA is the **disulfide bond**.

**Final Answer:** Disulfide bond