BIOL239 Lecture Notes - Lecture 7: Gynandromorphism, Spindle Apparatus, Colchicine
2 Mar 2018
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Individuals whose chromosome number is not an exact multiple of the haploid number ( n ) for the species are aneuploids ( an individual whose chromosome number is not an exact multiple of the haploid number for the species). For example, in a normally diploid species, an individual lacking one chromosome is monosomic (2 n 1), whereas an individual having a single additional chromosome is trisomic (2 n + 1). Monosomy, trisomy, and other forms of aneuploidy create a genetic imbalance that is usually deleterious to the organism. Autosomal aneuploidy is usually lethal: in humans, monosomy for any autosome is generally lethal, but medical geneticists have reported a few cases of monosomy for chromosome 21, one of the smallest human chromosomes. Although born with severe multiple abnormalities, these monosomic individuals survived for a short time beyond birth. Similarly, trisomies involving a human autosome are also highly deleterious.
