Meiosis

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Meiosis
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So FarMitosis

• Asexual Reproduction
• 1 parent contributes all of the genetic info.
• 1 Division
• Prophase, Metaphase, Anaphase, Telophase
• cloning of genetic info. exact copies.
• of Chromosomes remains the same.
• Somatic Cells.

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Meiosis

• Sexual Reproduction
• 2 parents, each contributing unique genetic
  material.
• 2 Divisions
• P, M, A, T, (pause) P, M, A, T
• Variation introduced daughter cells are each
  different from each other AND their parent cell.
• of Chromosomes is reduced by ½.
• Germ Cells.

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Meiosis

• Each parent contributes genes to the offspring.
• Genes are the hereditary units.
• Genes have alternative forms Alleles.
• Alleles are different forms of a gene.
• EYES Blue, Green, Hazel, Brown
• Totally new combinations of alleles are put
  together with sexual reproduction.
• Variation ?Natural Selection ? Change

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Germ Cells

• Cells that eventually become gametes (sperm or
  egg).
• Begin as Diploid (2N) cells (cells with two
  sets of chromosomes).
• Homologous Chromosomes pairs of chromosomes
  with the same genes, but perhaps different
  alleles.
• End as Haplid (1N) cells (cells with only one
  set of chromosomes) due to meiosis.

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Chromosomes

• Lots of Terms to get used to

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Life Cycles
1N
2N
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Gametic Life Cycle

• Meiosis produces Gametes sperm egg.

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Zygotic Life Cycle

• Meiosis produces Zygotes (zygote-like).

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Sporic Life Cycle

• Meiosis produces Spores.

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Meiosis 2 Divisions

• Unduplicated chromosomes
• S-phase
• Duplicated chromosomes
• 1st Division
• 2nd Division

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Meiosis I
CROSSING OVER
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Crossing Over
VARIATION
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Meiosis I
INDEPENDENT ASSORTMENT
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Independent Assortment
VARIATION
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Meiosis I
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Meiosis II
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Mitosis vs Meiosis
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Spermatogenesis

• Each of the products of meiosis has the potential
  to become a sperm cell.

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Oogenesis

• Only one of the meiotic products becomes the egg.
• The rest become polar bodies dumping grounds
  for excess DNA.

VARIATION
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Fertilization

• Which of the billions of people meet and have
  offspring?
• Which of the zillions of sperm cells finally
  reaches the egg?

VARIATION