LS1a_L15_notes08-1

LS1a_L15_notes08-1 - LIFE 5-UUA AUA UUC GAA 5-TTA ATA TTC...

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PROF. ROBERT LUE NOVEMBER 4, 2008 1a L I F E S C I E N C E S 5’-TTA ATA TTC GAA AGC TGC ATC GAA AAC TGT GAA TCA-3’ 3’-AAT TAT AAG CTT TCG ACG TAG CTT TTG ACA CTT AGT-5’ 5’-UUA AUA UUC GAA AGC UGC AUC GAA AAC UGU GAA UCA-3’ 1
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Nucleic acids in action: transcription and the programming of the cell 1. RNA structure and function - Structural components of RNA - Relative stability in comparison to DNA 2. From DNA to RNA: the process of transcription - Overview of intracellular information transfer - RNA polymerase transcribes RNA from a DNA template - Bacterial transcription as a model - The starting and stopping of transcription in bacteria - Eukaryotic transcription requires multiple initiation factors - Eukaryotic DNA is packaged with proteins - Eukaryotic RNA transcripts are chemically modified 3. Transcription is regulated in several different ways - Packaging of eukaryotic DNA facilitates gene regulation - Combinatorial control of gene transcription determines different cell types 2
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Eukaryotic regulation of transcription by upstream elements Upstream regulatory sequences modulate the transcription of eukaryotic genes Activator proteins bind to upstream sequences and enhance the rate of transcription initiation Inhibitor proteins bind to upstream sequences and reduce/inhibit transcription The control region can include downstream sequences A gene’s control region can span tens of thousands of base pairs A large protein complex called Mediator can serve to link activators and inhibitors to the polymerase looping gene As indicated by the results of our breakout experiment - the transcription of eukaryotic genes involves regulatory proteins that can act even when bound to DNA thousands of base pairs away from the promoter that they inFuence. This means that a single promoter and gene can be controlled by the combined effects of several regulatory sequences scattered over long stretches of DNA. Therefore, the gene control region consists of the entire expanse of DNA involved in regulating transcription of a gene, including the promoter, where the general transcription factors and the polymerase assemble, and all of the regulatory sequences to which regulatory proteins bind to control the rate of the assembly processes at the promoter. In higher eukaryotes such as humans, it is not unusual to ±nd the regulatory sequences of a gene scattered over distances as great as 50,000 base pairs. Although much of the spacer DNA between regulatory sequences is not recognized by regulatory proteins, it may facilitate transcription by providing the spatial Fexibility needed for communication between DNA-bound proteins. It is also important to remember that much of the DNA in gene control regions is packaged into higher-order forms of DNA plus protein (chromatin), thereby compacting its length. We will discuss this in greater detail a little later in this lecture. Transcription regulation involves the activities of both activator proteins and inhibitor proteins.
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LS1a_L15_notes08-1 - LIFE 5-UUA AUA UUC GAA 5-TTA ATA TTC...

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