Incomplete Dominance and Meiosis Notes

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Incomplete Dominanceand Meiosis Notes
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Incomplete Dominance

• Sometimes one trait is not completely dominant
  over another
• Both alleles have a degree of influence

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Codominance

• There is neither a dominant or recessive trait
• Both are expressed independently

• Roan cattle are crossed from white and red
  cattle, resulting in red cattle with white
  blotches

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Sex Cells

• An egg or sperm cell
• A sex cell carries half the number of chromosomes
  found in other body cells
• Eggs female sex cell
• Sperm male sex cell

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Review Mitosis

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

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Mitosis vs. Meiosis

• Mitosis is cell division to produce new cells
• New cells are identical to the original cell

• Meiosis is cell division to produce sex cells
• New cells are not identical to the original cell

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Meiosis

• Chromosomes are duplicated once, and the nucleus
  divides twice
• Making of sex cells

• Prophase 1
• Metaphase 1
• Anaphase 1
• Telophase 1
• Prophase 2
• Metaphase 2
• Anaphase 2
• Telophase 2

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Sex Chromosomes

• The chromosomes that carry genes that determine
  the sex of offspring
• Eggs contain only the X chromosome
• Sperm contain an X or Y chromosome

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Cells vs. Chromosomes

• Sex cells are eggs or sperm that contain ½ the
  number of chromosomes, including one sex
  chromosome
• Sex chromosomes contain genes that determine the
  gender of offspring

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5050 Chance

• Male sex chromosomes are XY
• Female sex chromosomes are XX

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Sexual Reproduction

• Parent cells are known as sex cells or gametes
• Two parent cells join together to form a new
  individual
• Gametes have half the number of chromosomes in
  your body cells

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Less is More

• Why is it important that sex cells have ½ the
  number of chromosomes?
• Ensure the newly formed offspring have the
  correct number of chromosomes (46)

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Homologous Chromosomes

• Chromosomes with matching information