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Karyotypes. a picture of someones chromosomes Centromere.

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Presentation on theme: "Karyotypes. a picture of someones chromosomes Centromere."— Presentation transcript:

1 Karyotypes

2 a picture of someones chromosomes Centromere

3 Banding Pattern Bands are large segments of DNA **Remember what chromosomes are made up of

4 Exception: Position 23 Chromosome Pair #23 determines sex

5 Female 23 rd pair of chromosomes are homologous Both chromosomes are X chromosomes X

6 Male 23 rd pair of chromosomes are NOT homologous One chromosome is X and the other is a Y chromosome

7 Disjunction Normal separation of Chromosomes and Chromatids during Meiosis I and Meiosis II (Anaphase I & II)

8 Normal Karyotypes Has 46 chromosomes for humans Arranged in 23 pairs

9 NON-disjunction Nondisjunction during Meiosis I Metaphase IAnaphase I Failure to separate homologous pairs

10 NON-disjunction Nondisjunction during Meiosis II Metaphase II Anaphase II Failure to separate Chromatids

11 What does nondisjunction cause? Missing Chromosomes – Monomy Embryo/Fetus will not survive Means 45 chromosomes Exception is this can occur on 23 rd chromosome pair Extra Chromosomes – Trisomy Means 47 chromosomes –Down Syndrome (Trisomy 21) –Patau Syndrome (Trisomy 13) –Klinefelters Syndrome (XXY) –Turners Syndrome (X-) –XYY Syndrome –And many more………….

12 Trisomy 21 – Down Syndrome Extra Chromosome 21

13 Trisomy 13 – Patau Syndrome Extra Chromosome 13 Symptoms can include Cleft lip or palate Close-set eyes -- eyes may actually fuse together into one Decreased muscle tone Extra fingers or toes Hernias Hole, split, or cleft in the iris Low-set ears Mental retardation Scalp defects (absent skin) Seizures Single palmar crease Skeletal (limb) abnormalities Small eyes Small head Small lower jaw Undescended testicle

14 Klinefelters Syndrome (XXY) Extra Sex Chromosome X

15 Turners Syndrome (X-)

16 Jamie Lee Curtis XY male with Androgen Insensitivity Syndrome (AIS) resistant to androgens –the hormones responsible for male sexual development


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