Chromatin and Chromosomes

Chromatin

Chromatin is a structure within cells, consisting of DNA and protein. Chromatin provides a template for the synthesis of ribosomes, which are present in all living cells as well as in the nuclei of eukaryotic cells. The material that composes chromatin is called chromatin or protoplasm, both deriving from the Greek “chroma,” meaning colour and “plasma,” meaning substance.

When referring to visible traits or features such as hair colour or eye colour, scientists usually use the term genotype instead of phenotype. But chromatin is an important player in the creation of both genotype and phenotype. In fact, it played a significant part in myostatin biosynthesis, which leads to muscle growth and the development of cricketers’ large muscles.

Chromosomes

Chromosomes are DNA molecules containing replicated genetic material (genes) that occur within the cells that constitute an organism. Chromosomes are also present in cells from plants, microscopic amoeba, and other organisms and sensory transducers such as eyes and ears. Chromosomes contain genes that encode proteins critical for all cellular functions. These genes are organized into long strands of “chromatin” (sometimes called chromosomes) which run like beads on a string throughout a cell.

Chromatin is concentrated into a compact structure in the cell nucleus. Chromatin includes both DNA and protein, which are together called chromosomally associated proteins or histones. These histones are involved in the packaging of certain genes, as well as in the silencing of other genes. DNA is the genetic material that makes up chromosomes and is tightly wrapped around the histones. The process of packaging genes into chromatin differs from one part of the cell to another, but all cells contain DNA and chromatin in different amounts. In some cells, this may be almost all that they contain; while in others it may be only a portion of total cellular content.

Chromatin was first discovered by Max Delbruck in 1953 when he observed a stain with a chemical similar to acid-fast (AF) stains used in cancer pathology which stained chromosomes very brightly, yet did not affect embedded cell nuclei.

Each of the cells in the human body contains 46 chromosomes. There are 23 pairs of homologous chromosomes (also called autosomes or non-sex or somatic chromosomes) and one pair of sex chromosomes: two X-chromosomes in females and one X- and Y-chromosomal pair in males. Female somatic cells have two copies of each of the autosomal chromosome pairs, while male somatic cells have only one copy of each. Chromosomes are also found in nearly all eukaryotic organisms, with both their organelles and their DNA being composed of chromatin.

Chromosomes are typically composed of long strings of DNA and proteins. Chromatin can be bound together by a protein called histone, which is made up of repeating units of three basic proteins (labelled ε, α and σ). The structural components of the chromosomes are microtubules and a type of protein-based scaffolding called the nuclear lamina. Chromosomes are also associated with proteins called “histone” complexes.

Chromatin and Chromosome: Difference

Chromatin is a substance consisting of DNA and protein that forms chromosomes within the nucleus of eukaryotic cells. It forms genetic material. Chromatin is made up of nucleosomes made from eight core histone proteins, wrapped around by 146 base pairs of DNA, for a total length of approximately 10 million base pairs per cell (human cells).

Conclusion

In this article, we have discussed in detail the structure, content and function of chromosomes, the formation of nuclei and their relation with chromatin (chromosome). Not all of the properties of chromatin are well known. A relatively new property is “chromatin condensation”, where small regions inside a chromosome become compacted. The compacted region will act like a switch controlling which genes are transcribed into RNA and which genes are turned off.