BIOL10003 Lecture Notes - Lecture 18: Single Transverse Palmar Crease, Down Syndrome, Fissured Tongue
12 Nov 2018
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Document Summary
Lecture 18 behaviour of chromosomes and alleles: segregation of alleles. Karyotype shows all the chromosomes in order (size, centromere position) Karyogram a drawing of chromosomes with banding shown. Homologous chromosomes same length, centromere location, gene loci (but may be different between m and f inherited chromosomes) Can be stained in different ways fish (fluorescent in situ hybridisation) Related species have the same number of chromosomes. Aneuploidy: adding or losing a chromosome or two often sex chromosomes. Older eggs are significantly more likely to have abnormally functioning spindles - which causes an increased rate of chromosomal problems in the mature eggs. Risk increases with maternal age; issue with cohesion molecules nondisjunction at anaphase i of meiosis. Trisomy 21 (trisomy 18 and 13 can also survive full term no others) Separation in toes, fissured tongue, simian crease etc. Small testis, reduced testosterone, delayed or incomplete puberty, infertility, light body hair, breast enlargement.
