Chapter 16 Bio

Chapter 16 Bio - ICQ5 Chapter 6 and Chapter 7 (partly)...

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ICQ5 – Chapter 6 and Chapter 7 (partly) Chapter 6 Chromosome Structure - Bacterial chromatin (e. coli) is a closed covalent circle, packaged into condensed nucleoprotein complex (nucleoid) o insulated loops – a nick does not affect entire DNA DNA probably fixed to proteins in a way that prevents free rotation supercoiled loops o SMC proteins organize and compact DNA (4fold) Hinge-mediated dimerization – 2 SMCs bend so N- & C-terminals together form head domain and 2 SMCs form hinge intermolecularly Coiled-coil dimerization – 2 SMCs in antiparallel coils, N-term of 1 and C- term of other form head domains (incorrect) o Other proteins (H-NS, HU, Fis, IHF) similar to eukaryote histones - Animal somatic cells have homologs (2 versions of each chromosome 2n) o interphase – DNA, RNA, protein, molecular synthesis euchromatin – predominant during interphase, less condensed, actively transcribed heterochromatin – more condensed, not actively transcribed G1 (active protein, lipid, carb synthesis) S (DNA rep, histone syn) G2 - Mitosis o Prophase – visible chromosomes (sister chromatids), nucleolus disappears, nuclear membrane disassembles, spindle formation o Metaphase – spindle attach to kinetochore (at centromere), metaphase plate o Anaphase – centromere divides, sister chromatids move to opposite poles o Telophase – spindle disappears, nuclear membranes form, nucleoli reform, chromosomes decondense, 2 identical daughter cells - Meiosis o Prophase I Leptotene – chromatin begin condensation, chromomeres (beads) appear on chromosomes (unique for each chromosome)
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Zygotene – homologous pairs, synapsis (chromomere-chromomere pairing) forms bivalents/tetrads Pachytene – crossing over ( genetic recombination ) Diplotene – homologous pairs held by chiasmata (cross over site), ribosomes, proteins, fats, carbs, cytoplasmic components synthesized Diakenesis – maximum condensation, spindle formation, nuclear membrane disassembles o Metaphase I – spindles on either side attach to homologous pairs, metaphase plate o o Telophase I – 2 new spindle replace single spindles, no DNA rep b/t meiosis I/
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Chapter 16 Bio - ICQ5 Chapter 6 and Chapter 7 (partly)...

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