Cell Biology

Histones are basic proteins that package DNA into nucleosomes in eukaryotic cells. They are rich in positively charged amino acids, specifically lysine and arginine, which facilitate binding to negatively charged DNA.
Answer: Lysine and Arginine.

Step 1: Understanding Heterochromatin and Euchromatin.
Heterochromatin and euchromatin are two types of chromatin found in the nucleus.
- Heterochromatin: - It is densely packed and stains darker. - It is transcriptionally inactive and contains genes that are not being actively transcribed.
- Euchromatin: - It is loosely packed and stains lighter. - It is transcriptionally active and contains genes that are being transcribed.
Step 2: Conclusion.
Heterochromatin is dense and inactive, while euchromatin is less dense and active in gene expression.