BIO SCI 97 Lecture Notes - Lecture 5: Turner Syndrome, Xyy Syndrome, Edwards Syndrome
11 Sep 2017
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Document Summary
E. coli genome is ~1,000x longer than e. coli. Densely packed small region called the nucleoid. Supercoiling is just a bunch of dna coiled. Can"t supercoil b/c their chromosome is linear. Chromosomes condense during mitosis during the m phase. Each chromosome is half dna, half protein. Half of the proteins histone proteins. Dna has an overall negative charge b/c of the phosphate backbone. 5 major histone proteins: h1, h2a, h2b, h3, and h4. H1 is not part of the nucleosome. Proteins help compact the nucleosomes further and further until they are tightly compacted. Histone h1 stabilizes the 30 nm fiber. Chromatin is decondensed in areas of active gene expression. Rna polymerase can also decondense chromatin so genes can be transcribed. Euchromatin: not tightly condensed easy gene expression. Heterochromatin: tightly condensed few active genes. Heterochromatin: comes in 2 types: facultative & constitutive. Consists of several types of repeated dna sequences. Chromatin at the centromere is highly condensed.
