Bio - Lecture 9(NEW EXAM)

Bio - Lecture 9(NEW EXAM) - In approximates the middle of...

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Sheet1 Page 1 Mitosis: Division of cells Chromatin is the entire collection of a cell's DNA and the associated proteins Chromosomes are a single DNA strand and the associated proteins -Chromosomes change shape throughout the life of the cell Linear, double-stranded DNA and histones (proteins) make nucleosomes Bundles of nucleosomes further compact into condensed chromosome form Chromosome structure: Some sections of chromatin are not used as templates for RNA These sections are called heterochromatin Those sections that are expressed are called euchromatin Karyotypes are an arrangement of an individual's chromosomes HUmans have 23 pairs, or 46 chromosomes, and in karyotypes they are generally arranged (and numbered) from longest to s h -X is the female (XX) -Y is the male (XY) The number of chromosomes needed to define an organism is the haploid (n) number In humans, we have a diploid (2n) number since we get one set from each of our parents In diploids, the matching chromosome pairs are called homologous and the chromosomes are homolouges of one another
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Unformatted text preview: In approximates the middle of chromosome is a unique heterochromatin site called the centromere Afer DNA (chromosome) replication, each chromosome is connected to its sister chromatid at the centromere site-Chromosomes have their own centromere-Chromatids share a centromere with its "sister" Cell Cycle: As cells grow, they pass through acycle of five phases called the cell cycle The five phases are:-G1 phase: Major portion of cell's life-S phase: Replication of genome (synthesis)-G2 phase: Preparation for cell division (gap)-M Phase: organelles and chromosomes divide (mitosis)->Composed of four stages-C phase: Cytoplasm divides (cytokinesis)-G1, S1 and G2 are collectively called interphase-Depensding on the cell type, the cell cycle varies in duration Most animal cells "rest" between G1 and S phase-called G0 phase...
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This note was uploaded on 05/06/2008 for the course BIOL 121 taught by Professor Lopez during the Fall '07 term at Lansing.

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