Chromatin Composition and Structure
Chromatin is a molecular complex composed of DNA and proteins, primarily histones, which are permanent components throughout the cell’s life. Other molecules transiently associate with chromatin during cell formation, including various types of RNA (rRNA, tRNA, and mRNA), enzymes involved in transcription and replication (polymerases), enzymes involved in condensation cycles, and enzymes that regulate gene expression. Therefore, chromatin is a dynamic structure.
The composition of chromatin is: RNA
Read MoreNuclear Pore Complex: Structure and Function
Nuclear Pore Complex: Structure
Each complex consists of the association of numerous proteins, known as nucleoporins, that presents an octamer provision. The pore complex can be distinguished:
- Eight column proteins, which form the side walls of the pore. Each is attached to the perinuclear space by anchoring proteins. In addition, there are eight radial proteins that project from the columns into the lumen, delimiting a central channel pore or opening.
- A cytoplasmic outer ring protein consisting of
Chromosome Structure and DNA Organization in Eukaryotes and Prokaryotes
DNA Organization in Chromosomes: DNA to Chromatin to Chromosomes
Viral and Bacterial Chromosomes: Much simpler than those of eukaryotes, single DNA molecule.
Prokaryotic Chromosomes: No associated proteins, less genetic information.
Virus Chromosome: Single or double-stranded DNA, can be a covalently closed circle (X174 & Polyoma), can be linear (T-even 2x).
- Bacteriophage λ is a linear double-stranded DNA molecule before infection, closes into a ring after infection of the host. Long DNA molecule