Lecture 04

Lecture 04 - Lecture 04 10.07.08 The History of...

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Lecture 04 // 10.07.08 - The History of Evolutionary Thinking i. Genetic flaws shared by different species - why are they important? Example : Chromosome 17 in humans. Gene for peripheral myelin protein 22 (PMP-22) flanked on both sides by identical DNA sequences (CMT1A repeats). Considered a mistake because one SMT1A repeats (yellow) occasionally lines up with wrong chromosome and repeats during meiosis, which causes unequal crossing over. Individual chromosomes may have an abnormal 0 or 2 copies of PMP-22 (orange). Zygote (offspring) with only 1 copy or 3 copies of PMP-22 (orange) has neurological problems. What does this have to do with homology? i. We can see a connection between human, bonobo, and chimpanzee, which CMT1A repeats present. Also, there is a relation between orangutan and gorilla, which CMT1A repeats absent . Genetic flaw was present in the most recent common ancestor of chimps, bonobos, and humans. b. Is it more than an abstract concept? i. Yes! Molecular homology is the basis of biomedical research. Model systems are useful in biomedical research because all organisms are related to one another and share genetic code and cellular processes. It is also used in genetic engineering of crop plants. ii. Drug safety can be tested on rats. Why malfunctioning genes cause cancer - examined in yeast. DNA repair can be studied in bacteria. All because we share the common ancestor . c. Bacteria Bacillus Thuringiensis produces toxin that is lethal to cotton pests (bollworms). The bacterial genes that encode toxin can be inserted into crop plants--cotton. Bacillus Thuringiensis cotton express toxin and kills the pest. It is grown on millions acres worldwide. All because bacteria and plants share a common ancestor that uses the same genetic code . II.
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This note was uploaded on 03/31/2009 for the course BILD 632282 taught by Professor Henter during the Fall '08 term at UCSD.

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Lecture 04 - Lecture 04 10.07.08 The History of...

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