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Nondisjuncti on Homologous pairs do not move apart during Meiosis.

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Presentation on theme: "Nondisjuncti on Homologous pairs do not move apart during Meiosis."— Presentation transcript:



3 Nondisjuncti on Homologous pairs do not move apart during Meiosis

4 Nondisjuncti on aneuploidy- abnormal number -2n + 1 ex. Down’s trisomic - 2n - 1 ex. Turner’s monosomic

5 Turner’s Syndrome trisomic monosomic

6 Trisomy 21 Trisomic 2n + 1

7 Down Syndrome / Trisomy 21

8 Turner Syndrome X monosomic 2n - 1

9 Klinefelter’s Syndrome u 2N + 1 (2N + 2, 2N + 3) u Genotype u Genotype: XXY (XXXY, XXXXY) u Phenotype u Phenotype: male, but sexual development may be poor. Often taller than average, mental development fine (XXY), usually sterile. u More X = more mental problems

10 Kleinfelter’s Syndrome

11 Klinefelter’s Syndrome Comment: I have read that George Washington may have had Klinefelter’s. Taller than average, no children

12 Trisomy X u 2N + 1 u Genotype: XXX u Phenotype: taller female, but sexual development poor. (Mental impairment common in many reports, not in others???)

13 Edward’s Syndrome



16 Also known as Trisomy 18 Almost every organ system is affected. 1:10,000 live births. Children with full Trisomy 18 generally do not live more than a few months. Characteristics: small jaw, low-set ears, and a strawberry-shaped head.

17 Patau Syndrome

18 This person would suffer from serious eye, brain, & circulatory defects as well as cleft palate. 1:5000 live births. Children rarely live more than a few months.

19 Patau Syndrome

20 Jacob’s Syndrome XYY Tall Lean Acne prone Crooked eye Anger difficulties Some cognitive difficulties



23 Translocations

24 Prader-Willi Deletion on chromosome 15 - father imprinted

25 Angelman Deletion on chromosome 15 - mother imprinted

26 u Gene expression and inheritance depends on which parent passed on the gene. u Usually caused by different methylations of the DNA.


28 Imprints are "erased" in gamete producing cells and re-coded by the body according to its sex.

29 u Prader-Willi Syndrome and Angelman Syndrome u Both lack a small gene region from chromosome 15. u Male imprint: Prader-Willi  Female imprint: Angelman

30 Gene Mutations

31 Chromosome “M” -small circles of DNA located in mitochondria and plastids of plants. Mitochondria reproduces itself and it passes it DNA along to its daughter organelle only.


33 Chromosome “M” - All “M” Chromosomes come from mom

34 These genes help form proteins involved in respiration. Defects in these genes cause Mitochondrial diseases such as mitochodrial myopathy, diabetes, heart disease, Alzheimer’s disease. Cummulative mutations may role play in aging

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