MEIOSIS (The Production of Gametes)

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MEIOSIS(The Production of Gametes)
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Introduction

• Human Body Cells have 46 chromosomes (somatic
  cells)
• B. Gametes have 23 chromosomes
• 23 from Dad 23 from Mom 46
• Gametes Sperm Cells and Eggs
• Zygote Fertilized Egg

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II. Chromosome s

• Each species has own chromosome
• 1. Humans 46
• 2. Fruit Flys 6
• 3. Dogs 78
• http//www.kean.edu/breid/chrom2.htm

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III. Terms

• Diploid (diploid cells) 2n
• 1. 2 copies of each gene for each trait
• 2. 1 copy from Mom 1 from Dad
• 3. 2 copies of each chromosome
• Each pair of chromosomes
• Homologous Pair

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III. Terms

• Monoploid (Haploid ) 1n
• (Monoploid Cells)
• 1. 1 copy of each gene
• 2. 1 copy of each chromosome
• Gametes are 1n
• Meiosis Gamete Production

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IV. Phases of Meiosis

• Prophase I
• 1. DNA is replicated during Interphase
• 2. Homologous Pairs of chromosomes come
  together
• 3. Crossing over occurs
• a. Chromosome Tips are Exchanged
• b. Increases Genetic Diversity

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Crossing Over
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IV. Phases of Meiosis

• B. Metaphase I
• 1. Homologous Chromosomes line up along equator
• C. Anaphase I
• 1. Homologues separate and move to opposite
  poles of cell

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IV. Phases of Meiosis

• D. Telophase I
• 1. 1st meiotic division takes place
• a. 2 cells are produced

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Meiosis I
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IV. Phases of Meiosis

• E. Prophase II
• a. Both Cells begin Meiosis II
• F. Metaphase II
• a. Chromosomes line up at equator
• b. Each Chromosome is made up of 2 chromatids

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IV. Phases of Meiosis

• G. Anaphase II
• 1. Chromatids separate and move to opposite
  poles
• Telophase II
• 1. Nuclear membranes reform
• 2. 2nd division occurs
• 3. 4 cells have been produced
• 4. Each cell is 1n
• 5. Each gamete is different!!

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Meiosis II