CSB349L3 - CSB349H1 Lecture 3 September 20th, 2010 The...

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CSB349H1 Lecture 3 September 20 th , 2010 The topic for today is a continuation on the question of what is really in the human genome. A large part of our genome is repeats and most of it isn’t even genes (or human genes), they are transposons, etc. Only 20,000-25,000 genes is still a huge number of genes. Questions for today’s class: Where do these genes come from? How do we detect genes changes in copy number? The major mechanism of the origin of genes is gene duplication and divergence; the vast majority of genes came from other genes. There are many different mechanisms for gene duplications and for gene divergence after duplications. The mechanism represented is gene duplication by retrotransposition, where our own genes can make copies of themselves. The CDC14B gene on chromosome 9. The figure illustrates four different alternative splice sites for the gene). The reason we know this gene CDC14B retrogene is on chromosome 7 and was created by retrotransposition as it shows the structure of an RNA element even though it is DNA and was copied from RNA back into DNA. ..hallmark is _____________________________. Tandem gene duplication (getting two gene copies on the same chromosome): Gene dupliplication on the chromosome, creates tandem repeats on the genome (most prevelant form of gene duplication). What happens to genes after they duplicate? One of the copies is generally lost as natural selection makes it require mutations, become non-functional, and be deleted. On some occasions, the genes stay similar and stay on the genome. Sub-functionalization may also occur, where the functions of the ancestral gene is divided among the two genes. Neofunctionalization may occur where there is still selection to preserve the original function of the gene, but mutations allow for a new function on the other gene to occur. The best example of gene duplication and divergence is the globin locus which uses oxygen to carry iron
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This note was uploaded on 12/03/2010 for the course CSB CSB349 taught by Professor V.tropepe,a.moses during the Fall '10 term at University of Toronto- Toronto.

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CSB349L3 - CSB349H1 Lecture 3 September 20th, 2010 The...

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