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Eukaryotic Genes. Oct. 6, 2004. Emerging Reality - 2003. Small RNAs that silence genes, and alter the transcription initiation site. Eukaryotic Gene Expression (Revised Cartoons). 25.1. 25.2. Transcription Control. RNA transcript: removing introns to mRNA. 26.7. Regulatory Complexity.
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Eukaryotic Genes Oct. 6, 2004
Emerging Reality - 2003 Small RNAs thatsilence genes, and alter the transcription initiation site
25.2 Transcription Control
Diversityjunction • Class of Ig: • Membrane bound • Soluble Immune Loci:Light & Heavy Chains Combine
Light chain is similar, butwithout the “D” class ofdiversity, reducing the possiblediversity. Total diversity offinal antibody is the multiple ofpossibilities between the LightChain and the Heavy Chain How does it work? Heavy chain
Process of “Exon” Selection: DNA to Protein 23.5 Light Chain
30 51 5 6 1,239,300 × 150 8,262 ═ (~3x104) < Genome Number of Proteins Coded How many are possible? Heavy Chain Functional Tetramer Light Chain V Region D Region 27 J Region Total Total # human antibodies > 1010when soluble and membrane-bound counted
Ponder these questions: • How many different proteins does an organism produce? • How many different proteins can an organism potentially produce? • How does this compare to knowing the number of transcription units (“genes”)? • What does the “genome map” identify? • How does an organism “know” which of the proteins to produce from a given “locus,” in a particular cell, at a particular time, under a given condition?