Mitosis in Onion Root Tip Cells

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Mitosis in Onion Root Tip Cells
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Onion root tip mitosis
Interphase

• cell grows in size
• cell replicates DNA in preparation for mitosis
• individual chromosomes not clearly discernable
• nucleolus may be visible as dark spot
• nucleus is apparent

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Onion root tip mitosis
Prophase

• chromatin in nucleus begins to condense and
  becomes visible under light microscope
• spindle fibers (microtubules) attach to
  centromeres of chromosomes
• nuclear envelope starts to break down

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Metaphase
Prophase
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Onion root tip mitosis
Metaphase

• spindle fibers align chromosomes along center of
  cell (metaphase plate)

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Onion root tip mitosis
Anaphase

• as spindle fibers shorten, paired chromosomes
  separate and move to opposite sides of cell

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Onion root tip mitosis
Telophase

• chromosomes are at opposite sides of cell
• nuclear envelope reforms
• cytokinesis begins, in which a new cell wall will
  be created along the metaphase plate and two
  daughter cell will be formed

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View of Onion root tip using 400x magnification
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Overview of phases of mitotic cell cycle
interphase
interphase
prophase
metaphase
anaphase
telophase