BIO 1140 Lecture Notes - Lecture 21: Cytoskeleton, Centromere, Apoptosis
8 Oct 2016
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Additional dna, the sequence ttaggg (humans) repeated thousands of time. With replication, that sequence shortens, but protects the coding regions of our chromosomes. Additional sequence rich in t and g, in animal cells tend to be 2000-3000 base pairs long, on the 3" segment. Shortens every time the cell divides, because rna primer is removed, left with a 3" overhang because no free oh group at the end for polymerase to come in and add nucleotides. W/out extra non-coding region, the chromosome would shorten every time it divides, start shortening desirable gene therefore telomere is a protection mechanism. At end of each chromosome, buffer = telomere, non coding, only there to serve as a cap so that every time cell divide, chromosome shortens but don"t lose coding region. Limit of number of cell division a cell can undergo. Length of telomere determines # of cell divisions a cell can undergo = hayflick limit.
