Lecture 11

Lecture 11 - Lecture 11 Chapter 15(3,4,5,6 skim only...

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Lecture 11 – Chapter 15 (3,4,5,6 skim only) Control of Gene Expression Transcripts are edited o In eukaryotic cells, mRNA has a cap and tail added o Some parts are removed (introns) and others remain to be expressed (exons) o If we have a protein, figure out the sequence of amino acids, then you can determine possible base pair sequence, then we have a “transcript”, if we could figure out where on the DNA that transcript matched then we would be able to locate the gene Splicing o Alternative splicing may make more products Control of gene expression: prokaryotes o Operon - sequence of genes operating together o Lac Operon – bound protein inhibits transcription and thus the operon is turned off o Turned off – repressed o Tuned on - transcribed When lactose is present the gene needs to be turned on Lactose binds to the protein which alters its shaped so it cannot bind, allowing transcription to occur so enzymes can be made to break down lactose Key to turning gene off: binding of a protein to DNA Control of gene expression o Genes may be turned off or on by signals from other genes: important in development Gene switches o Adding extra molecules groups to the DNA may prevent transcription o Some genes are switched in the embryo and these switches persist for the
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Lecture 11 - Lecture 11 Chapter 15(3,4,5,6 skim only...

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