Packaging of DNA
The process by which DNA molecules’ long, linear strands are bundled and arranged inside the cell nucleus is known as “DNA packing.” To accommodate the large length of DNA into the comparatively small nucleus, compaction is required.
- Nucleosome Formation: Nucleosomes are formed when DNA is coiled around histone proteins in the initial stage of DNA packing. A nucleosome is made up of around 147 base pairs of DNA looped around a core octamer of histone proteins (two copies of each of the histones H2A, H2B, H3, and H4). The DNA is wrapped around the histone core of this nucleosome core particle, giving it a look similar to beads on a string.
- Chromatin Fiber: Chromatin fibers are higher-order structures made of increasingly compressed and arranged nucleosomes. Different parts of the genome exhibit varying degrees of compaction due to variations in the exact arrangement of nucleosomes inside chromatin fibers. The following stage of compaction, in which nucleosomes are further folded into a more condensed fiber, is commonly modeled after the 30nm chromatin fiber.
- Chromatin Loops and Domains: Chromatin organizes itself into loops and domains at several levels beyond the 30nm chromatin fiber. By bringing distant sections of the genome closely, these loops and domains help regulate interactions between regulatory elements like enhancers and promoters and affect gene expression.
- Chromosome Structure: At last, the chromatin is arranged into distinct chromosomes, with a single, long DNA molecule enclosed in a protein-associated helix.
Eukaryotic Genome Organisation
The Eukaryotic Genome Organisation is the functional and spatial arrangement of DNA within the nucleus of eukaryotic cells. Eukaryotic genomes are defined by linear chromosomes contained within a membrane-bound nucleus, in contrast to prokaryotic genomes, which are usually arranged as circular chromosomes within the cytoplasm. In this article, we will learn about the organization of the eukaryotic genome, epigenetic modifications, chromatin remodeling, and eukaryotic gene families in detail.
Table of Content
- Genome Organization in Eukaryotes
- Chromosome Structure and Packaging of DNA
- Packaging of DNA
- DNA-Level Eukaryotic Genome Organisation
- Eukaryotic Gene Families
- Control Points of Gene Expression
- Conclusion – Eukaryotic Genome Organisation
- FAQs – Eukaryotic Genome Organisation