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Unformatted text preview: Laboratory 10: Mitosis and the Laboratory 10: Mitosis and the Cell Cycle Objectives Objectives Understand why cells divide Learn how the process of mitotic division differs from plant and animal cells Understand mitosis and how it relates to the cell cycle Introduction Introduction Why do cells divide? Growth Repair Reproduction Mitosis is occurs constantly in/on the human body and the cells are identical Newborns have 3 trillion cells & adults have 60 trillion; this is 20 times more cells DNA in humans is ≈ 6 ft. long Cell Cycle Cell Cycle
G1 Phase – Cell can stop mitotic events and function normally S Phase – DNA replication occurs G2 Phase – Time just before mitosis Mitosis – Cell replication G0 Phase – Cell stops mitosis The Steps of Mitosis The Steps of Mitosis Interphase Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis Valuable Vocabulary Valuable Vocabulary Chromosome – the packaged DNA Chromatid – the two halves that make up the chromosome Centromere – the connecting point of the chromatids Diploid – a full set of chromosomes; humans have 46 Interphase Interphase The cell is engaged in metabolic activity and performing its prepartions for mitosis Nucleus is wellformed Chromosomes are not clearly discerned in the nucleus Stages G1, S & G2 are included Prophase Prophase Genetic material becomes condensed; it becomes easier to move that way The nucleolus disappears. Each duplicated chromosome appears as the sister chromatids joined Prometaphase Prometaphase The nuclear membrane dissolves Microtubules attach at the centromeres and the chromosomes begin moving Kinetochore microtubles attach the centrosomes at each end Metaphase Metaphase Longest phase; approx. 20 minutes Centrosomes are now at opposite ends Chromosomes line up on the metaphase plate (equator) of the cell, forming the ‘spindle’ Anaphase Anaphase The paired chromosomes separate at the kinetochores and move to opposite sides of the cell Sister chromatids separate By the end, each end has a complete set of chromosomes Telophase Telophase Two daughter nuclei begin to form Nuclear envelope begins to reform Chromosomes become less condensed The division of the nucleus is now complete Cytokinesis Cytokinesis Division of the cytoplasm and everything in it Then a cleavage furrow forms to pinch off the cell into two new cells Mitosis Mitosis Prophase Metaphase Anaphase Nucleus Division Telophase Cytokinesis – Rest of the cell divides; organelles split up How to Animals & Plants Differ? How to Animals & Plants Differ? Cytokinesis Plants will form a cell plate from the inside out along the equator that becomes the cell wall Exercise 1: Whitefish Blastula Exercise 1: Whitefish Blastula
Interphase Prophase Metaphase Telophase Anaphase Exercise 2: Onion Root Tip Exercise 2: Onion Root Tip
Interphase Prophase Metaphase Cytokinesis Telophase Anaphase ...
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