Lecture 37 Eukaryotic gene expression

Lecture 37 Eukaryotic gene expression - Lecture 37...

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Lecture 37 Regulation of gene expression in eukaryotes Campbell, Chapter 18 Learning Objectives; Note that these objectives require an integration of this lecture with previous lectures. 1.  Explain how DNA methylation and histone acetylation affect chromatin structure and transcription 2. Define eukaryotic transcriptional control elements and explain how they influence transcription 3.  Explain the role of promoters, enhancers, activators, and repressors in transcription control 4.  Explain how eukaryotic genes can be coordinately expressed and how this contrasts with bacterial operons. 5.  Describe the roles played by small RNAs on gene expression.
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How is gene expression regulated in eukaryotes? All organisms must regulate which genes are expressed at any given time. In multicellular organisms, gene expression is essential for cell specialization The latest estimate is that a human cell contains approximately 23,000 genes. Protein coding sequences  (exons) represent only about about 1.5% of the genome.  Of these, only a fraction is expressed in any particular cell type.  * Some of these genes are expressed in all cells all the time. These so-called  housekeeping genes  are  responsible for routine metabolic functions (e.g. respiration) common to all cells. * Some of these genes are expressed all the time but only in certain cells that have specialized in a  particular way. For example, a B cell expresses continuously the gene for the antibody it  synthesizes.  *Some are expressed only at a certain time in the cell’s or organism’s life cycle (recall the stages of the  the cell cycle). * Some are expressed only as conditions around and in the cell change. For example, the arrival of a  hormone may turn on (or off) the transcription of certain genes in that cell.
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Differential Gene Expression With few exceptions, all the cells in an  organism are genetically identical. The difference between different cell  types of a particular organism is not due to different genes being present  but rather to the production of  different proteins. differential gene expression   selective expression of different  genes by cells with the same  genome.  How do we know that this is true?  We can analyze DNA, RNA and protein from two  different cell types from the same organism and see that the DNA is identical, but the RNA and protein  are vastly different.
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DNA Signal Gene NUCLEUS Chromatin modification Chromatin Gene available for transcription Exon Intron Tail RNA Cap RNA processing Primary transcript mRNA in nucleus Transport to cytoplasm mRNA in cytoplasm Translatio n CYTOPLASM Degradation of mRNA Protein processing Polypeptide Active protein
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This note was uploaded on 11/14/2010 for the course CHE 131 taught by Professor Kerber during the Spring '08 term at SUNY Stony Brook.

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Lecture 37 Eukaryotic gene expression - Lecture 37...

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