Telomerase and telomere length

Telomerase and telomere length - Telomerase and telomere...

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Telomerase and telomere length 3-26-07
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Telomeres are chromosome ‘end caps’ that consist of thousands of the DNA non-coding repeat, TTAGGG - In a sense, these end caps act like shoelace tips by: preventing tip fraying & tip fusions (non-homologous end ining) joining)
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Facts about telomere length • It is genetically determined • It is highly variable from species to species and from individual to individual: – 5-15 kb in humans; 5 50 kb in mice; ( not proportional w lifespan) – 25-150 kb in mice; ( not proportional w lifespan) • It is variable from cell type to cell type in adult is variable from chromosome to chromosome It is variable from chromosome to chromosome • It is variable from cell to cell •I t goes down with age gg
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Relevance of telomere maintenance/lenght Cells: – Telomere length determines the replicative life span of a cell in tissue culture – Shortening of telomeres in tissue culture cells results in cells reaching their proliferation limit, “Hayflick limit”, and permanent G0 cell cycle arrest (senescence). ther effects of shortening : apoptosis and genomic instability – Other effects of shortening : apoptosis and genomic instability If you artificially maintain the telomere length the cells become immortalized rganisms Organisms – Crucial in the germ line to maintain species over generations – Cellular aging has been linked with organismal aging, but the evidence for is link is sparse this link is sparse. – Limiting cell proliferation capacity might be related to tumor prevention. By extrapolation from cells: if you artificially maintain telomere length in n organism would you immortalize it as well ? an organism would you immortalize it as well…?
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Telomere maintenance issues and rotection mechanisms: protection mechanisms: • Chromosome ends are recognized as breaks and trigger the repair enzymes, chromosome fusion, or optosis: apoptosis: Create a special chromatin structure by sing specialized end capping proteins and a T loop structure Using specialized end capping proteins and a T loop structure • Using epigenetic modifications important to keep a closed. hetrochromatic conformation hromosome ends shorten during each division • Chromosome ends shorten during each division because of the DNA end replication problem Elongate the ends using a specialized reverse transcriptase named telomerase
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Telomere-binding proteins cap the chromosome ends and revent them from being recognized as DNA breaks prevent them from being recognized as DNA breaks - rand overhang G strand overhang 150-200n
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This note was uploaded on 09/28/2008 for the course BIO 4400 taught by Professor Tumbar,td during the Spring '07 term at Cornell University (Engineering School).

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Telomerase and telomere length - Telomerase and telomere...

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