Final answer:
The major difference between chromatin and heterochromatin is the level of DNA condensation. Chromatin, in its euchromatin form, is less condensed, facilitating transcription, whereas heterochromatin is highly condensed, containing mostly inactive genes.
Step-by-step explanation:
Major Difference Between Chromatin and Heterochromatin
The major difference between chromatin and heterochromatin lies in the degree of condensation and the accessibility of the DNA. Euchromatin represents a less condensed form of chromatin, where DNA is loosely packaged around nucleosomes, facilitating access to DNA for processes such as transcription and replication. In contrast, heterochromatin is highly condensed, with DNA tightly packed and generally less accessible for transcription. This compact structure typically contains genes that are not active in transcription, as the additional chromatin proteins present in heterochromatin obscure the DNA. These regions often correspond to the centromeres and telomeres of chromosomes.
During interphase, chromatin can exist in either state, with euchromatin being the site of active gene transcription and heterochromatin containing inactive genes. This distinction is crucial for understanding how gene regulation and expression occur within a cell.
Experiments with chromatin and DNase treatment have shown that euchromatic regions degrade faster than heterochromatic regions, suggesting that active genes are more exposed in euchromatin due to its less condensed structure.