Genetics

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Genetics
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Gregor Mendel

• Austrian Monk
• Worked with garden peas
• Father of modern genetics

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Mendel

• Click to view

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• Developed rules for genetics
• Law of Segregating Traits
• Traits defined now as alleles
• Alleles defined as part of DNA that codes for a
  physical characteristic

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Chromosomes segregating
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Nuclear Division

• Mitosis
• division of nucleus to give two exact copies of
  the parent
• occurs in somatic cells (non-gamete producing
  cells)
• used for maintenance and growth

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Mitosis

• First stage is G1
• Cell is producing enzymes for division

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Mitosis

• Next is DNA replication
• A copy of DNA is made for the new cells
• Enzymes involved
• Helicase
• DNA polymerase
• Ligase

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Replication

• Helicase unwinds DNA helix
• DNA Polymerase places the correct base pairs new
  strand
• Ligase forms the bonds

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Replication

• Click to start movie

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G2

• G2 is the next phase before Nuclear division
• Used to produce enzymes for nuclear division
• Short time in entire cycle

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Prophase

• Prophase
• Chromosome condensation
• Nuclear membrane disappears
• centrioles replicate
• spindle fibers appear (animals only)

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Metaphase

• Chromosomes line up along the equator of cell
• forms a dyad (two Chromosomes)

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Anaphase

• Centromere duplicates and the chromosomes
  separate
• Pulled to the ends of the cell by the spindle
  fibers

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Telophase

• Nuclear Membrane returns
• Chromosomes relax
• Two new offspring cells formed

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Completed Process

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Next presentation on Meiosis
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Meiosis

• Used for the production of gametes
• Found in Ovaries and testes
• Called the reduction division because there will
  be 1/2 of the total number of chromosomes present
  in the offspring cells

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Meiosis

• Process is similar to mitosis
• Differences in the first division of nucleus
• The line up of chromosomes in the form of a tetrad

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Metaphase 1 of Meiosis
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Meiosis

• Tetrad formed during chiasmata
• the pair of homologous chromosomes will separate
  during anaphase
• the cell has a brief interkinesis, then divides
  by mitosis to form 4 separate gametes

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Comparison of Mitosis and Meiosis