Chromosomal disorders are due to the change in the number of chromosomes present. This can be categorised into various types: Aneuploidy: loss or gain of a chromosome. This happens due to non-disjunction of chromatids when chromatids fail to separate during cell division. This results in one gamete having two copies of one chromosome and ...
Its effects are not as severe as in other structural defects. 4. Translocation: The shifting or transfer of a set of genes or part of a chromosome to a non-homologous one is known as translocation. There is no addition or loss of genes, only the rearrangement occurs.
Chromosomal Abnormalities in Humans. Chromosomes are thread-like structure present in the nucleus that carries hereditary information in the form of genes which is passed from parents to offspring. Every species has a characteristic structure and number of chromosome present. Due to certain irregularities at the time of cell division, ...
Each human cell contains 46 (2n) chromosomes present as 23 pairs (n pairs), out of which 22 are autosomes and 1 pair of sex chromosomes. Chromosomal disorders result from structural changes or numerical changes in chromosomes.
Acute Myelogenous Leukemia: In this type of cancer, bone marrow and cells derived from it show the presence of a short chromosome named as “ Philadelphia (Ph1) chromosome”. 22 nd chromosome loses a part of its arm which gets translocated to the distal end of the 9 th chromosome. It is not transmitted to the offspring.
Changes in one chromosome parts, whole chromosome or chromosomal sets are known as “chromosomal aberrations”.
1) Deletion: A portion of the chromosome is lost during cell division. A portion of chromosome without the centromere lags during anaphase movement and are lost from reorganising nuclei or digested by nucleases. The resulting chromosome lacks certain genes, that gets inherited to offspring.