Chromosome and Chromatid

Chromosomes are thread-like or rod-shaped structures in biological organisms that carry DNA information. The two strands of a chromosome that are identical to each other are known as chromatids. Cell division is aided by chromatids, which allow cells to duplicate and replicate one other.

A chromosome is a piece of genetic material that carries all of the attributes and characteristics of an organism. “Chroma” and “Soma,” which mean “color” and “body,” respectively, are Greek terms. The two strands of a chromosome that are identical to each other are known as chromatids.

Chromosomes and Chromatids

In eukaryotic creatures, chromosomes are present in the nucleus, whereas in prokaryotic organisms, there is only one ring-shaped chromosome, known as genophore. Genes are found on chromosomes and store the genetic information of an organism.

On one chromosome, two similar structures are kept together by the centromere. All of this is referred to as “chromatid.” As a result, each chromosome has two chromatids with a centromere connecting them. As a result, chromosomes are shaped like an X. The scientific study of cell division and chromosomes is known as cytogenetics.

Chromosomes

Chromosomes are thread-like structures found inside the nucleus of animal and plant cells. Hofmeister was the first to notice them, and Waldeyer coined the phrase. Chromosomes are made up of DNA and proteins that hold it together. They can take the form of a rod or a thread. They are condensed chromatin fibres that operate as hereditary vehicles by storing and transmitting coded genetic information. Only during karyokinesis do chromosomes emerge. The number of chromosomes in a species is constant. In gametophytic or haploid forms, there is only one set, and in sporophytic or diploid forms, there are two sets.

Since chroma means colour and soma means body, the name chromosome implies that these are colourful bodies observable under a microscope.

The scientists first saw these heavily stained remains in the late 1880s. In the early 1900s, Thomas Hunt Morgan discovered a link between the X chromosome and gender and eye colour in fruit flies. Histone proteins bind to big DNA molecules and condense them inside chromosomes, which are unique structures. Without such packaging, a big DNA molecule cannot fit inside a cell’s small nucleus.

A small region termed the centromere or main constriction connects the two chromatids on each chromosome. Arms refer to the two segments of a chromosome or chromatid on either side of main constriction. Iso Brachial chromosomes have equal arms, while heterobrachial chromosomes have unequal arms.

Based on the Position of Centromere, Chromosomes are divided into Four Types:

• Telocentric: Centromere terminal
• Acrocentric: Centromere inner to telomere
• Sub metacentric: Centromere sub-median
• Metacentric: Centromere median or in middle

A chromosome has one or more secondary constrictions close to the distal part of the arm, in addition to the primary constriction or centromere. A satellite is the segment of the chromosome that is present above secondary constriction. The chromatin thread connects the satellite to the secondary constriction.

Chromatids

A chromatid is one-half of a replicated chromosome. Before cell division, chromosomes duplicate and produce identical twins, which unite at their centromeres. Sister chromatids are the joined strands, and each strand is referred to as a chromatid. Genetically, these sister chromatids are identical. During the anaphase of mitosis, they detach from one another. Each divided chromosome is referred to as the daughter chromosome at this point.

Chromatin fibres create chromatids during meiosis and mitosis. Chromatids are made up of skeletal proteins and DNA. When wrapped around proteins in a specific order, it’s called a nucleosome. Chromatin fibres are nucleosomes that are tightly wrapped. Chromosomes are chromatin strands that have been compressed and are found inside the nucleus. Each chromatid replicates to produce an X-shaped structure during cell division.

Each chromosome separates from the centromere and travels towards the pole during mitosis. A sister chromatid, now known as a daughter chromosome, is given to each daughter cell. As a result, two unique but identical cells are formed. At the metaphase plate, homologous pairs of parental chromosomes align up during meiosis.

Each pair, referred to as a bivalent or tetrad, travels away from one another to generate two daughter cells. When sister chromatids are in close proximity to each other, genetic material is exchanged. Sister-chromatid exchange, or SCE, is a term for this type of disease. During SCE, a few or more chromatids are broken and rebuilt.

Nondisjunction is a condition in which chromatids (in mitosis) or homologous chromosomes (in meiosis) are unable to separate properly during cell division. 

This condition can occur during mitosis’ anaphase. As a result, the daughter cells’ chromosomal distribution is uneven. It has the ability to trigger tragic outcomes such as Down syndrome and Patau syndrome.

Difference between Chromosomes and Chromatid

Conclusion

In eukaryotic creatures, chromosomes are present in the nucleus, whereas in prokaryotic organisms, there is only one ring-shaped chromosome, known as genophore. Genes are found on chromosomes and store the genetic information of an organism.On one chromosome, two similar structures are kept together by the centromere. All of this is referred to as “chromatid.” As a result, each chromosome has two chromatids with a centromere connecting them. As a result, chromosomes are shaped like an X. The scientific study of cell division and chromosomes is known as cytogenetics. Chromosomes are thread-like structures found inside the nucleus of animal and plant cells. Hofmeister was the first to notice them, and Waldeyer coined the phrase. Chromosomes are made up of DNA and proteins that hold it together.