BIOL 121 Mitosis Lab fix.docx

BIOL 121 Mitosis Lab fix.docx - BIOL 121 Lab Mitosis...

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BIOL 121 Lab: Mitosis Objectives: Study the cell cycle; be familiar with the events that occur during interphase and mitosis Distinguish between the different stages of mitosis in plant and animal cells Determine the frequency of various stages in the cell cycle of plant and animal cells Cell cycle Most eukaryotic cells move through an ordered sequence of events called the cell cycle, during which their chromosomes become duplicated and 1 copy of each duplicated chromosome separates into each of 2 daughter cells. Proper regulation of the cell cycle is vital for multicellular organisms. The cell cycle is divided into 2 major phases, interphase and mitosis. Each of these phases consists of several stages. Interphase is divided into G1 (gap 1), S (synthesis), and G2 (gap 2). During interphase the DNA in the nucleus is in the form of a chromatin net, and individual chromosomes are not visible under the light microscope: G1 = primary growth and biosynthesis. S = duplication of centrioles, replication of DNA. At the end of S, each chromosome consists of 2 identical sister chromatids joined at the centromere. Humans have 23 pairs of chromosomes in the nucleus of each cell (except for reproductive cells) for a total of 46 chromosomes. When a cell divides, each daughter cell must end up with all 46 chromosomes, so before cell division can happen each chromosome must be replicated (copied).
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G2 = preparation for cell division; organelles replicate, chromosomes begin to condense, microtubules begin to assemble at spindle; Mitosis is a process of cell division in which 1 diploid parent cell gives rise to 2 genetically identical diploid daughter cells (asexual reproduction). Cell division by mitosis produces new cells for growth, wound repair, and replacement of cells that wear out or die. Mitosis consists of nuclear division (chromosomes) and cytokinesis (cytoplasmic division). Mitosis occurs by a sequential progression through prophase, prometaphase, metaphase, anaphase, and telophase: Prophase = DNA that was duplicated in S portion of interphase condenses into threadlike chromosomes; nucleoli disassemble and disappear; spindle fibers begin to form.
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