Meiosis: A special type of cell division

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Meiosis A special type of cell division

• By Crystal Carroll

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WHY IS MEIOSIS IMPORTANT?

• Sexual reproduction begins with Meiosis
• Zygote grow through Mitosis--resulting in an
  organism
• Evolutionary change
• Overview of Meiosis

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INTERPHASE I

• Longest phase
• Chromosomes replicate

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PROPHASE I

• Homologus chromosomes begin to condense
• Synapsis occurs
• Crossing over occurs

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METAPHASE I

• Tetrads line up
• Spindle fibers attach

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ANAPHASE I

• Tetrads separate
• Centromeres remain in tact

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TELOPHASE I

• Two haploid cells form at each pole
• Each chromosome has two sister chromatids

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CYTOKINESIS

• Division of the cytoplasm
• Cleavage furrows form
• No further replication of the genetic material

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INTERKINESIS

• Transistion period

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PROPHASE II

• New spindles form
• No crossing over

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METAPHASE II

• Chromosomes line up on metaphase plate

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ANAPHASE II

• Centromeres split

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TELOPHASE II CYTOKINESIS

• Nuclei form
• Cytokinesis occurs
• Mitosis occurs

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MEIOSOS IS NOT FLAWLESS

• The most common cause of pregnancy failure
• Arise from mistakes
• During egg formation
• More frequent as women age
• Gain or loss of whole chromosomes

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Meiosis