BIOL 3333 1st Edition Lecture 21Transmission pattern for fragile x: Pregnancies: - approx. 15% of all pregnancies result in sponantous abortions- 1/2 of these show chromosomal abnormalities- in approx. 1/200 live births, a chromosomal abnormality can be detected- majority of these is downs syndrome and balanced translocationsPrenatal Diagnosis: Amniocentesis- performed at about 16 weeks of pregnancy- this is when fibroblasts can be safely collected from amniotic fluid- requires mitogenic stimulation of cells prior to analysisThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Chorionic Villus Sampling (CVS)- can be performed around the 9th week of pregnancy- from extra embryonic cells which are actively dividingDrosophilia Mitotic Chromosomes: - 4 pairs, 2n=8- 2 acrocentrics (XX)- two sets of metacentrics (2-3)` - one pair of dot chromosomes Polytene Chromosomes in Drosophila:- in salivary glands of larva, chromosomes undergo DNA replication without ensuring segregation- chromosomes will replicate approx. 10 times - giving rise to structures contains 1024X the amount of euchromatic DNA - DNA associated w/ the centromeric heterochromatin will be under replicated relative to DNA of the arms - will fuse to form a chromocenter*every chromosome arm has distinct binding pattern*changes in binding pattern could be correlated to changes in data generated from linkage
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