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Our body is made of cells. Cells contain a nucleus. Chromosomes are found in the nucleus. DNA is present in chromosomes. One of the two similar halves of the duplicated chromosome is chromatid. During cell division, two types of chromatids are found in the cell which perform the task of cell division. Chromatids are produced during the initial steps of the cell division whereas sister chromatids are duplicated by the same chromosomes but non-sister chromatids exhibit during the meiosis of metaphase 1.
DNA
We have genes in our body that contain information. DNA is made up of many genes. DNA is the genetic material of all organisms. Many viruses like AIDS, Tobacco Mosaic, Orthomyxovirus, Hepatitis C, SARS etc. have RNA as their genetic material. In prokaryotic cells, DNA is circular and present in the cytoplasm as a constituent of the Pro chromosomes and plasmids. In eukaryotic cells, DNA is in linear form and widely concentrated in the nucleus as a constituent of the chromosome which is called the nuclear DNA. A small number of DNA is found in mitochondria and plastids, this small number of DNAs is called extranuclear or organellar DNA.
This organellar DNA is also circular similar to prokaryotic DNA. DNA is also present in some viruses. DNA is present inside the Chromosome. Genome in humans contains 3.2 billion DNA nucleotide pairs which are divided into 22 different autosomes and 2 sex chromosomes. Each Chromosome has hundreds to thousands of genes that carry the instructions to make protein. Chromosomes are usually thread-like structures that are found in the nucleus of cells of both plants and animals.
Homozygous and Heterozygous
Before replication, one chromosome is made up of one DNA molecule and during replication, DNA molecules get facsimile and these two molecules together are called chromatids. In the further division of cells, these chromatids get isolated too longitudinally and become different chromosomes. The chromatid pairs are usually genetically identical, that’s why they are called homozygous. But if the mutation happens, the pair of chromatids exhibit differences and are thus called heterozygous.
Chromatids can be of two varieties, one is a sister-chromatid and another one is a non-sister chromatid.
Conclusion
As we see the difference between sister chromatid and non-sister chromatid mainly lies in their structure. Sister chromatids are two exactly similar copies of a chromatid. Sister chromatids have the same genes. Non-sister chromatids are chromosome couples having the same length, patterns and position of the centromere. We see that chromatids permit cells to collect and cluster two copies of their information in devising cell division. This is important to corroborate that daughter cells are healthy and they function properly.
