BIOL 202 Lecture Notes - Lecture 15: Ploidy, Trisomy, Fundamental Theorem Of Arithmetic
20 Feb 2018
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When we talk about the number of chromosome sets in the cell, we talk about ploidy: euploid: good number of chromosomes. Monoploid (n): one copy of each chromosome (ex: gametes are monoploid) Diploid (2n): two copies of each chromosome. Triploid (3n): three copies of each chromosome. Tetraploid (4n): four copies of each chromosomes. For more than 2 copies: autoploids" gene sets are entirely from their own species, alloploids have sets of chromosomes from another related species. If an individual has an abnormal number of chromosomes it"s called aneuploidy . Trisomy: three copies of one chromosome (abnormal) Monosomy: one copy of a chromosome (abnormal) A geneticist crosses a 2n with a 4n individual: 2n give 1n gametes, 4n gives 2n gametes, 1n+2n=3n offspring. Start with two diploid parents: one parent goes through defective meiosis and ends up with 2n gametes instead. Ex: vermilion trait seen in last lecture; this is similar except the whole set of chromosomes didn"t separate.
