The following point highlight the five main types of structural variation in chromosomes. The types are: 1. Deletion or Deficiency 2. Duplications 3. Translocations 4. Inversions 5. B-Chromosomes. Type # 1. Deletion or Deficiency: A deficiency means deletion of a small portion of a chromosome resulting in loss of one or more genes. A deficiency originates from breakage occurring at [...]
In this article we will learn about:- 1. Origin of Inversions 2. Types of Inversion 3. Effects 4. Uses. Origin of Inversions: Inversion was first discovered by Sturtevant in 1921 in Drosophila. Later it was detected in a wide variety of plant and animal species. Inversions occur spontaneously, and can be induced artificially. In many organisms, inversions are found in [...]
In this article we will discuss about the paracentric inversion in chromosome. Chromosome Pairing and Crossing Over: In paracentric inversions chromosome pairing occurs by loop formation in the inverted region; the centromere remains outside the loop. Crossing over in the loop causes the formation of dicentric chromatids which produce bridges at anaphase. Chromatid bridges may be formed at AI or [...]