Packing

Definition

Packing is the process by which DNA is tightly wound around histone proteins to form nucleosomes, making up the chromatin structure. This compaction regulates the accessibility of DNA for transcription and other processes.

5 Must Know Facts For Your Next Test

1. Chromatin packing can be in a more relaxed (euchromatin) or condensed (heterochromatin) state, which influences gene expression.
2. Histone modifications such as methylation and acetylation play critical roles in determining the level of chromatin packing.
3. DNA methylation typically promotes tighter packing and gene silencing.
4. ATP-dependent chromatin remodeling complexes can alter nucleosome positioning to regulate gene accessibility.
5. The degree of chromatin packing is crucial during cell differentiation and development, impacting which genes are expressed.

Review Questions

• How does histone acetylation affect chromatin packing?
• What is the difference between euchromatin and heterochromatin in terms of gene expression?
• Explain how ATP-dependent chromatin remodeling complexes contribute to gene regulation.

Related terms

Euchromatin: A loosely packed form of chromatin that is generally associated with active transcription of genes

Heterochromatin: A tightly packed form of chromatin that usually correlates with gene silencing

Histone Modification: Chemical changes to histone proteins that can impact chromatin structure and gene expression