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 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 [...]
In this article we will discuss about:- 1. Meaning of Pericentric Inversion 2. Chromosome Morphology 3. Occurrence of Pericentric Inversion. Meaning of Pericentric Inversion: When the inverted segment is large, a loop is formed during synapsis and centromere is included in the loop. Crossing over in the loop causes the formation of deficiency-duplication chromatids. Chromosome pairing and crossing over positions [...]