Lecture 3.ppt

Based on 1000 bp as the average length of coding

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Unformatted text preview: f an organism? *based on 1,000 bp as the average length of coding sequence per gene. How do you find the coding region of a gene? LC! 1 1/23/13 Polytene chromosomes in Drosophila: -DNA replication without mitotic divisions Cloning mammals - 512+ double helices (or more!) Fusion of enucleated oocyte and donor cell nucleus by electrical current. Egg also activated to begin development. Proof: nuclei of adult vertebrate somatic cells can be TOTIPOTENT Resulting embryos implanted into uterus of pregnant sheep. Of 434 sheep oocytes, only one survived--Dolly Dolly and first kid, Bonnie Three principles of differential gene expression Polytene chromosomes from different tissues have same overall banding pattern 1) Every cell contains the complete genome established in the fertilized egg. 2) The unused genes are not destroyed or mutated, they retain the potential for being expressed. 3) Only a portion of the genome is expressed in each cell and a portion of the RNA synthesized is specific for that cell type̶examined in insect cells Puffs correlate with specialized functions in the salivary gland 2 1/23/13 Fly salivary gland polytene chromosomes Where are genes...
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This document was uploaded on 04/03/2014.

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