How are chromosomes put together?

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• How are chromosomes put together?
• How do new cells get their chromosomes?
• How do new organisms get their chromosomes?
• Compare and contrast these two processes.

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How are chromosomes put together?
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The packaging of CHROMOSOMES! (protein and DNA)
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HUMAN DNA AND ITS PACKAGING IN HOMOLOGOUS
CHROMOSOMES
MOM
DAD
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HUMAN DNA AND ITS PACKAGING IN HOMOLOGOUS
CHROMOSOMES
MOM
DAD
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How do new cells get their chromosomes?
MITOSIS
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INTERPHASE
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EARLY PROPHASE condensation
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PROPHASE Mitosis begins
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METAPHASE Alignment of the chromosomes
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TELOPHASE Re-formation of the nuclei and
CYTOKINESIS
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RESULT TWO NEW DAUGHTER CELLS WITH IDENTICAL SET
OF CHROMOSOMES OF PARENT CELL
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6
MITOSIS
6
6
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Very accurate copies of chromosomes!
94
78
34
18
6
46
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How do new organisms get their chromosomes?
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MIEOSIS
INTERPHASE (future egg or sperm)
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FIRST PROPHASE
Exchange of segments
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FIRST TELOPHASE AND FIRST DIVISION
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SECOND INTERPHASE
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SECOND PROPHASE
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SECOND METAPHASE perpendicular axis
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SECOND ANAPHASE
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SECOND TELOPHASE
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RESULT FOUR NEW UNIQUE DAUGHTER CELLS EACH WITH
HALF THE CHROMOSOMES OF THE ORIGINAL CELL
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NOTE THAT WHICH COPY OF EACH CHROMOSOME GOES TO
WHICH CELL IS COMPLETELY RANDOM
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Comparing Mitosis and Meiosis

• Number of divisions

6
6
6
6
3
3
3
3
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meiosis
mitosis
PROPHASE
METAPHASE
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Comparing Mitosis and Meiosis

• Number of divisions
• Number of chromosomes in daughter cells
• Genetic identity of daughter cells
• Where they occur

6
6
6
6
3
3
3
3
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• miTosis each daughter cells get TWO complete
  sets of chromosomes
• meiOsis each daughter cells get ONE complete
  set of chromosomes