Mitosis, Meiosis, DNA rep.docx - Mitosis Meiosis DNA...

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Mitosis, Meiosis, DNA Replication MITOSIS: The Cell Cycle Makes body cells (skin, stomach cells) Product: 2 identical diploid cells w 46 chromosomes each Process Begins as diploid cells with 46 chromosomes and ends as diploid cells w 46 Interphase: preparatory phase of mitosis, not actually part of it o G1: metabolic phase Longest in duration Cell grows and does normal cell activity o S phase: synthesis phase, DNA replication Cells work to accurately replicate each chromosome so identical sister chromatids can be made before cell division o G2 phase: preparing for cell division Short period Checkpoints to ensure that no errors will be passed to daughter cells o G0 phase: cells enter this phase if they stop dividing after cell division Prophase o Chromosomes visible bc of nuclear condensation o Nuclear structures begin breaking down o Spindles form o Centrioles migrate to opposite ends of nucleus Metaphase o Chromosomes align in middle of cell o Spindle fibers attach to chromosomes
Anaphase o Sister chromatids travel to opposite ends Centromeres divide o Marks beginning of cytokinesis Telophase o Chromosomes uncoil o Nucleus reforms o Cytokinesis continues o Animal cells- membrane pinches o Plant cells- new cell wall starts forming Cytokinesis- division of cytoplasm o Begins in late anaphase and finishes after mitosis o Actin fibers pull on contractile ring to create cleavage furrow in center of cell o Ring is pulled until the cytoplasm splits in two making 2 daughter cells MEIOSIS: USED FOR GENETIC VARIETY Makes gametes (sperm, egg cells) Product: non identical haploid cells with 23 chromosomes each Process Interphase: precursor for both meiosis and mitosis o Same steps as before Division occurs twice Prophase (I) o Chromosomes condense and pair up w homologous partner
o Crossing over occurs Gen info is exchanged b/w the chromosomes o Nuc membrane degrades o Leptotene Chromosomes condense Telomeres of chromosomes attach them to nuc membrane o Zygotene - beginning of synapsis Synaptonemal complex forms b/w

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