Choose the correct Statement about DNA packaging from the following.

Options

A. The beads-on-string structure in chromatin is packaged to from chromatin finers that are further coiled and condensed during metaphase.
B. A typical nucleosome contains 300 bp of DNA helix
C. Histones are rich in the basic amino acid residues glycine and arginine , both of which carry a positive charge .
D. In a typical nucleus , the region of chromatin which stains light is referred to as heterochromatin.

Answer

To solve the question regarding the correct statement about DNA packaging, we will analyze the information provided in the video transcript step by step.

### Step-by-Step Solution:

1. **Understanding DNA Packaging in Eukaryotes**:
- DNA in eukaryotic cells is packaged with the help of proteins known as histones.

**Hint**: Remember that histones play a crucial role in DNA packaging.

2. **Properties of Histones**:
- Histones are positively charged proteins, rich in basic amino acids such as lysine and arginine. This positive charge allows them to interact with DNA, which is negatively charged due to its phosphate backbone.

**Hint**: Focus on the charge interactions between histones and DNA.

3. **Formation of Nucleosomes**:
- A nucleosome is formed when approximately 166 base pairs of DNA are wrapped around a histone octamer (which consists of 8 histone proteins).

**Hint**: Keep in mind the specific number of base pairs associated with nucleosomes.

4. **Structure of Chromatin**:
- The arrangement of nucleosomes gives chromatin a "beads on a string" appearance. This structure is further coiled and condensed during cell division (metaphase).

**Hint**: Visualize the "beads on a string" structure to understand chromatin organization.

5. **Evaluating the Statements**:
- **Statement 1**: Correct - It describes the role of histones and nucleosome formation accurately.
- **Statement 2**: Incorrect - A typical nucleosome contains approximately 166 base pairs, not 300.
- **Statement 3**: Incorrect - Histones are rich in lysine and arginine, not glycine.
- **Statement 4**: Incorrect - The light-staining region of chromatin is called euchromatin, while heterochromatin stains dark and is transcriptionally inactive.

**Hint**: Cross-check each statement against the information provided in the transcript.

6. **Conclusion**:
- The only correct statement about DNA packaging is the first one, which accurately describes the role of histones and the formation of nucleosomes.

**Final Answer**: The correct statement about DNA packaging is Statement 1.