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Ploidy

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Ploidy is the number of chromosomes sets held by a particular organism in a cell.[1]

Haploid

The number of chromosomes in a sperm or egg cell, half the diploid number.

Diploid

The number of chromosomes in most cells except the gametes. In humans, the diploid number is 46.

Haplodiploidy

Some insects of the order Hymenoptera such as bees, wasps and ants, have no sex chromosomes, and, instead, sex is based on the number of sets of chromosomes found in the nucleus of each cell. Males develop from unfertilized eggs, and the females develop from fertilized eggs. The cells of the male Hymenoptera are haploid and their chromosomes are inherited only from the mother, as opposed to the females who inherit from both his mother and his father and is therefore diploid.[2]

Polyploid

Polyploidy results when cells acquire one or more sets of chromossomes beyond the normal number of sets[3]

Aneuploidy

Aneuploidy occurs as the result of changes in the individual number of homologous chromosomes in a set. This typically involves the loss of one chromosome of a homologous pair, also called monosomy or possession of an extra chromosome called Trisomy.[4] The aneuploid condition that results in three copies of a given chromosome is known as trisomy (2n+1).[3] The latter is an aneuploidy condition resulting in three copies of a given chromosome and is represented as trisomy (2n + 1).[3]

References

  1. Robinson, Tara Rodden (2005). Genetics for Dummies. Hoboken, NJ: Wiley Publishing. p. 24. ISBN 978-0-7645-9554-7. 
  2. Pierce, Benjamin (2003). Genetics: A Conceptual Approach. W. H. Freeman. p. 80. ISBN 978-1-57259160-8. 
  3. 3.0 3.1 3.2 Stansfield, William D.; Colomé, Jaime S.; Cano, Raúl J. Molecular and Cell Biology. New York: McGraw-Hill. p. 64. ISBN 0-07-139881-3. 
  4. Ness, Bryan D. (revised edition); Knight, Jeffrey A. (first edition), ed. (2004). Encyclopedia of Genetics. Pasadena, California/Hackensack, New Jersey: Salem Press. p. 403. ISBN 1-58765-150-5.