Chromosomes

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Chromosomes
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• Defined Tightly coiled DNA
• Forms during cell division
• New chromosomes must be made for the new cell
• 2 Parts
• 1) Chromatids two identical parts of a
  chromosome
• 2) Centromere Joins chromatids together

Chromosomes
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Karyotype

• Defined Picture of an individuals chromosomes
• Used to determine sex and chromosome defects
• Size of final pair indicates sex
• Same size XX female
• Different size XY male
• Normal human will have 46 chromosomes
• Which karyotype is a male?

Female
Male
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Diploid Cells

• Half of our chromosomes come from each parent (23
  from each parent)
• Diploid Cells Cells with the full set of
  chromosomes
• Somatic (non-sex) cells are diploid
• Created by mitosis
• Ex Skin, Muscle, Nerve, Blood Cells
• How many chromosomes do human brain cells have?

46
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Haploid Cells

• Haploid Cells Cells with ½ the total number of
  chromosomes
• Gametes (sex cells) are the only haploid cells
• Chromosome number is reduced by meiosis
• Ex Sperm, Egg, Pollen
• How do humans get 46 chromosomes?
• Haploid sperm cells (23) Haploid egg cell (23)
  Diploid zygote (46)

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Down Syndrome Whats Wrong?

• Writing notation
• 1st total chromosome
• 2nd Sex chromosomes
• 3rd extra or missing
• Down Syndrome 47, XY, 21

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Turners Syndrome Whats Wrong?

• Write the notation for Turners Syndrome.
• 45, X, -23
• or
• 45, XO, -23

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Pataus Syndrome Whats Wrong?

• Write the notation for Pataus Syndrome.
• 47, XY, 13

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Klinefelters Syndrome Whats Wrong?

• Write the notation for Klinefelters Syndrome.
• 47, XXY, 23

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Rat Karyotype

• What is the
• diploid number?
• haploid number?

• How many chromosomes would be in
• somatic cells?
• blood cells?

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Rat Karyotype

• How many chromosomes would be in
• gametes?
• rat egg cells?
• muscle cells?
• Is this a male or female rat?

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Quick Review

• Chromsomes are tightly coiled strands of DNA
• Diploid (somatic) cells contain the entire set of
  chromosomes
• Haploid (gametes) cells contain only ½ the total
  number of chromosomes