mitosis and meiosis - Reproduction - How we become...

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Reproduction - How we become multicellular As we have been trying to do all semester, we now need to talk about another characteristic of living organisms and that is the ability to grow via cellular reproduction. Why do cells divide? What are some of the things that are accomplished with cell division? Eukaryotic Cell Division Let’s begin by discussion and defining some very important terms a. somatic cells – body cells – cells that are diploid and divide via mitosis b. gametes – sex cells – these include both sperm and eggs c. chromatin – uncondensed DNA d. chromosome – condensed DNA – associated with proteins called histone proteins.
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e. chromatids – chromatids are the “arms” of a chromosome. f. sister chromatids – sister chromatids are chromatids that exist on the same chromosome. g. centromere – the centromere is the structure in the middle of a chromosome where the chromatids converge. It is also the location of the attachement of the mitotic spindle.
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h. mitosis – mitosis is duplication division – it occurs in somatic cells and results in cells with the same genome as the parental cell. Takes cells that were diploid and makes cells that are also diploid. i. cytokinesis – cytokinesis is the final splitting of a single cell into two new cells. j. meiosis – meiosis is reduction division – it occurs in gametes and results in cells with ½ the original genome of the parental cell. Takes cells that were diploid and makes them haploid.
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The Eukaryotic Cell Cycle There are four major phases or components of the cell cycle. They include the mitotic (M) phase, gap one (G 1 ), gap two (G 2 ) and synthesis or S phase. A. mitotic phase B. interphase 1. G 1 2. S 3. G 2
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Regulation of the Cell Cycle Why is regulation so important? Regulatory Check Points 1. G1 2. G2 3. M
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Mitosis in more detail Mitosis as it relates to the cell cycle. There are five phases to mitosis. These include propase, prometaphase, metaphase, anaphase, and telophase.
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A. Prophase - nucleolus breaks down - chromatin begins to condense into chromosomes each with two chromatids - mitotic spindle begins to form - centrosomes move away from each other B. Prometaphase - nuclear envelope breaks down - microtubules of spindle connect to chromosomes - microtubules extend from pole to equator of cell - chromosomes develop a kinetochore - some microtubules attach to kinetochore - others overlap to stablize cell - centrioles begin to migrate toward poles as well
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C. Metaphase - centrioles are at opposite ends of cell - chromosomes align themselves on metaphase plate
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This note was uploaded on 04/07/2008 for the course BIO Genbio taught by Professor Ferguson during the Fall '07 term at University of Colorado Denver.

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mitosis and meiosis - Reproduction - How we become...

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