HMB265H1 Lecture Notes - Lecture 17: Down Syndrome, Karyotype, Aneuploidy

• School: UTSG
• Department: Human Biology
• Course: HMB265H1
• Professor: Maria Papaconstantinou

Document Summary

Hmb265: lecture 17 - changes in chromosome number. So far looking at consequences of mutations. [1] euploidy: change in number of sets of chromosomes. Ex: a normally diploid organism has 2 sets of chromosomes. If individual has more or less than 2 sets. [2] aneuploidy: correct number of sets of chromosomes, but missing or extra single chromosome. Two main themes underlying the observations on chromosomal changes. Main observation when look at karyotypes w/i spp. [1] find that karyotypes highly conserved within spp. B/c genetic imbalances usually have selective disadvantage = few differences. This is why hybrids are often sterile. Closely related spp differ by few rearrangements. Must be mechanisms that preserve genetic material from one generation to another. Cases where end up with more or less sets of chromosome. Monoploidy = 1 set of chromosomes instead of 2. Polyploidy = more than 2 sets of chromosomes. Monosomy = only have one copy of particular chromosome instead of 2.