Question

Study the diagram given below and answer the questions that follows:

1. Identify the structure shown in the above figure.
2. Identify the labels P and Q.
3. Write the nature of histone proteins.
4. Distinguish between Euchromatin and Heterochromatin.

Answer 1

1. Nucleosome (basic unit of chromatin)
2. P - DNA wrapped around histones.
   Q - Histone core (H2A, H2B, H3, H4).
3. Basic, positively charged proteins called histones are essential for the packing of DNA in eukaryotic cells.
4. 
   

   Feature	Euchromatin	Heterochromatin
   Definition:	Loosely packed form of chromatin that is transcriptionally active.	Tightly packed chromatin that is transcriptionally inactive.
   Appearance:	Microscopic investigations show light staining (less dense).	darkly condensed and darkly stained under a microscope.
   Function:	permits the transcription and expression of genes.	primarily engaged in gene regulation and structural support.
   Examples:	genes that are involved in biological processes like the creation of proteins.	Barr body (female inactivated X chromosome), centromeric and telomeric DNA.