Surely all of us must have heard this term " CHROMOSOMES"- The interesting stuff residing in our cells and this is what we actually get from our parents.
The chromosomes which are the carriers of the genetic information, the genes are very wonderful structures. The DNA molecule as we all know is the hereditary material. It is a double stranded molecule, upon which lie the nitrogenous bases that are attached to one another by hydrogen bonds. This double stranded DNA molecule lies coiled around the histone proteins or as we call it the histone octamer. This structure together is referred to as nucleosome. This structure is what present in uncondensed form, that is usually referred to as chromatin. So usually our DNA lies in the nucleus of cell in the form of chromatin. When this chromatin gets condensed, that is the structure which we refer to as the chromosome.
Cell division , as we all know is characterized by different phases. Meiosis is characterized by a slightly different scenario than that of mitosis. Talking about mitosis, it is characterized by interphase and mitotic phase. The interphase is further divided into prophase metaphase, anaphase, telophase.
Of this metaphase is the one in which the chromosomes are visualized, which is actually the chromatin in condensed state.
And karyotyping is the procedure in which we extract these metaphase chromosomes.
The chromosomes are in the highest condensed state during this phase and appear as a bivalent with two arms, with the shorter arm referred to as p arm and the longer one as q arm.
And thus is the process of karyotyping, in which we arrest the chromosomes in their metaphase by adding colchichine. By Giemsa staining, the chromosomes are stained and are then visualized under the microscope. Several softwares are available which align the chromosomes according to their size and are thus numbered. This, then assists us in determining the chromosomal number, to help detect any chromosomal number abnormalities. Similar is with the structure of chromosome. Any additions or deletions as well as translocation can be detected.
This is karyotyping, which is one of the earliest and still in use method for determining chromosomal abnormalities.
Interesting isn't it?
Wondering if you could learn this!!
So, here we are!! SALSI Special Event: COUNT YOUR CHROMOSOMES is all about Karyotyping!!
Participate in this learn-with-fun brainstorming activity at no extra cost!!(Open to all participants registered at SALSI 2020)
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Post Courtesy: Dr. Shruti Pande (Scientific Coordinator, IACDG)