LEC08 - 10/13/2008 Announcements Lab 5 this week Quiz 2...

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10/13/2008 1 Announcements Lab 5 this week Quiz 2- Answer posted Wed. Prokaryotic Gene Regulation
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10/13/2008 2 Weak promoters have poor consensus sequences and initiate transcription Promoter sequence determines first level of regulation sequences and initiate transcription infrequently Strong promoters generally have good consensus sequences and initiate transcription often Many promoters are regulated by proteins as well Repressors inhibit transcription initiation Activators increase transcription initiation Three levels of transcription: -basal level -repressed -activated -35 -10
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10/13/2008 3 Activation: 1- recruitment of polymerase to promoter by increasing binding affinity 2- inducement of conformational change leading to open complex formation (allostery) DNA binding proteins can interact with one another at either adjacent binding sites or at distant binding sites (c p r tivit (cooperativity)
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10/13/2008 4 DNA bending proteins can facilitate these distal interactions Activation by recruitment RNA polymerase Repressor mRNA Repressors usually block transcription initiation by: interfering with RNA polymerase binding or preventing open complex formation
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10/13/2008 5 Related genes are often organized as operons Operon - an arrangement of genes in a contiguous linear array In an operon a continuous strand of mRNA carries the message for a related series of enzymes (polycistronic mRNA) Why are genes organized into operons? Genes encoding enzymes in a common pathway can all be induced simultaneously.
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This note was uploaded on 07/08/2009 for the course LIFESCI LS 3 taught by Professor Paulolague during the Fall '09 term at UCLA.

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LEC08 - 10/13/2008 Announcements Lab 5 this week Quiz 2...

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