320-21posted1 - Chromosome features Centromeres and...

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Unformatted text preview: Chromosome features Centromeres and telomeres Transposons: mobile chromosome elements. Chromatin & gene expression Nucleosomes & DNA packaging Chromatin modification & gene expression Position effects & X inactivation Lecture 21 Gene expression in eukaryotes Eukar yotic chr omosomes & gene r egulation Chromosome features Ch 13.1-13.3 Centromeres and telomeres Transposons: mobile chromosome elements. Chromatin & gene expression Ch 13.4 Nucleosomes & DNA packaging Nuclease hypersensitivity Position effects & X inactivation Regulating gene transcription Ch 18.1-18.2 Enhancers & DNA-binding proteins Signal transduction Epigenetics DNA methylation; genomic imprinting Regulation after transcription Ch 18.3-18.4 Gene regulation by splicing RNA interference Ridley ch 15 SEX Lectures 21 - 22 Ch 14.1 Chromosome anatomy Telomeres enable end replication not subject to repair only one per chromosome! Centromere Chromosome functions: replication and segregation Origins of replication many per chromosome spindle microtubules kinetochore microtubule attachment fluorescent antibody to CENP-E protein Specific proteins assemble at centromeres and kinetochores Telomere replication (lecture 9) 5 3 5 3 3 5 5 3 ?? fluorescent probe for TTAGGG Telomerase: inactive in adult somatic cells - telomeres get shorter reactivated in many tumor cells - cells are immortalized Transposons: mobile elements in genomes Dispersed repeats originate as tr ansposable elements = mobile genetic elements = tr ansposons : = DNA segments that can move from place to place in the genome. DNA transposons Depend on recombination activity of a DNA tr ansposase Retrotransposons . Transpose via an RN A inter mediate ; require r ever se tr anscr iptase First discovered in corn ( in 1940s, at CSH, by Barbara McClintock) as controlling elements that could move from one locus to another. Ch 14 pp 508-514 DNA transposons Transposase gene Autonomous element: self-sufficient Non-autonomous derivative:- transposase gene mutated or lost; moves only if enzyme supplied by another element. I nverted repeats Examples of DNA transposons- I nsertion sequences (I Ss) in bacteria - mediate F plasmid insertion into & excision from chromosomal sites.- Ac (autonomous) & Ds (nonautonomous) elements in corn- if insertion affects kernel color, color restored on excision in somatic cells: mosaic pattern produced.- P elements in Drosophila- invaded D. melanogaster worldwide in <50 years- useful for transgenics, and as mutagen. YFG white + RNA transposons 1 2 LTR LTR Proof of RNA intermediate: Cloned yeast Ty1 element, added intron: I ntron spliced out in new insertions!...
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This note was uploaded on 04/21/2010 for the course BIO 89329 taught by Professor Hollingsworth during the Spring '10 term at SUNY Stony Brook.

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320-21posted1 - Chromosome features Centromeres and...

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