Rucete ✏ Biology In a Nutshell
1. DNA and Chromosomes
- During cell division, DNA condenses into chromosomes to ensure accurate distribution to daughter cells.
- When not dividing, DNA exists in a less condensed form called chromatin.
2. Chromatin Structure
- Chromatin is a complex of DNA and proteins (mainly histones) that helps package DNA into the nucleus.
- It exists in two forms:
- Euchromatin
- Heterochromatin
3. Euchromatin
- Lightly packed form of chromatin
- Associated with actively expressed genes
- Found in regions of DNA that are being transcribed
4. Heterochromatin
- Densely packed form of chromatin
- Often contains silenced or inactive genes
- Helps maintain chromosome structure and regulate gene expression
5. Summary Comparison
| Feature | Euchromatin | Heterochromatin |
|---|---|---|
| Packing density | Lightly packed | Tightly packed |
| Gene activity | Active (expressed) | Inactive (silenced) |
| Appearance | Light under microscope | Dark under microscope |
| Function | Transcription | Structural + regulation |
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Biology in a nutshell