MCB 150 Lecture Notes - Lecture 12: Hydrolysis, Interphase, Sister Chromatids
7 Dec 2017
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Document Summary
Bases pair make a double helix. A very long double helix of dna (+associated proteins) is a chromosome. Dna molecules also in chloroplasts and mitochondria. In bacteria extended lengths of dna can be 1,000 times the width of the cell. In humans chromosomes stacked end to end would be 2 meters in length! Compact all that chromatin into a space that"s only 1 10 m. Bacterial chromosomes are supercoiled take less space. Done by topoisomerases nick (hydrolyze the phosphodiester linkages) dna wind or unwind reseal dna. Chromatin first described by r. kornberg in 1974 chromosome structure. Chromatin dna + protein beads on a string. Nuclease degrade the dna between the beads hydrolyze phosphodiester linkages. Nucleosomes the beads with only the amount of string or dna wrapped around physically touching those beads. High concentration of salt dna unwind itself from the beads leaving only beads".
