Differences Between Sister and Non-sister Chromatids

Sister vs Non-sister Chromatids

Isn’t it a wonder how a human body grows and develops? From the chance meeting of an egg cell and a sperm cell, a human is beginning to be born. The cells of the human body multiply in the process called mitosis. That is why we are growing and continue to build up muscle mass. Our unique characteristics are defined with deoxyribonucleic acid, or simply DNA. During our elementary grades, we are already studying the basics of human reproduction and cell replication. We have heard of the term “DNA” so much, yet we have passed by the term “chromatid.”

Clarence Erwin McClung coined the term “chromatids” in the early 1900s. Chromatids are two fiber strands which are fused together by a lone centromere, produced from the duplication of the chromosome in the early stages of cell division. After that, it will then separate to become individual chromosomes in the late stages. When the chromatids separate and move towards the opposite poles of the cell, they are now called “daughter chromosomes.” “Chromatids” are terms used in the process of either meiosis or mitosis. There are two forms of chromatids, sister or non-sister chromatids.

When you are sisters, probably you have the same face or have similar features. This is also true with sister chromatids. Sister chromatids are two identical copies of a chromatid. When we say “identical,” they are exact replicas of the parent chromatid. Sister chromatids have the same genes and the same alleles. During the S subphase of the interphase period, a full set of sister chromatids are produced when the entire cell’s DNA is duplicated. During a mitotic cellular division, identical chromatid pairs are divided into two dissimilar cells. Some studies showed that in some species, the sister chromatids are ones responsible for DNA repair. To have an even and correct distribution of the genetic information among daughter cells, cohesion of sister chromatids is necessary. When there is an uneven distribution of genetic information, possible defects may arise such as cancer and aneuploidy.

Non-sister chromatids are also called as homologues. They are chromosome pairs having the same length, staining pattern, centromere position as well as the same characteristics of genes at a particular loci. One non-sister chromatid is inherited from its mother while the other one is inherited from its father. Because of this, they are not identical. That’s why it’s called “non-sister.” Non-sister chromatids are created during meiotic cellular division. Meiosis is a type of cellular division that deals with the production of gametes, egg cells, and sperm cells. When the gametes unite or a crossover occurs, each chromosome in the pair will contain the biological features of the parent such as the color of the hair, eyes, and skin. There are 22 pairs of non-sister chromatids called autosomes and one pair of sex chromosomes. All in all, humans have 46 chromosomes. A child can inherit any characteristics of his parents because each pair in the chromosomes carries his parents’ traits.

Summary:

1. The term “chromatid” was coined by Clarence Erwin McClung in the early 1900s.

2. Chromatids are two fiber strands which are fused together by a centromere. It is produced from the duplication of the chromosome in the early stages of cell division.

3. There are two forms of chromatids, sister or non-sister chromatids.

4. Sister chromatids are two identical copies of a chromatid having the same genes and alleles.

5. Non-sister chromatids are also called homologues having the same length, staining pattern, centromere position, as well as the same characteristics of genes at a particular loci.

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