1 / 10

Human chromosomes

Human chromosomes. There are 46 chromosomes (23 homologous pairs) in each somatic cell 22 pairs of autosomes 1 pair of sex chromosomes XX = Female, XY = Male Karyotype - chromosomes are arranged according to shape and size. Nondisjunction and chromosomal disorders.

jerry
Download Presentation

Human chromosomes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Human chromosomes • There are 46 chromosomes (23 homologous pairs) in each somatic cell • 22 pairs of autosomes • 1 pair of sex chromosomes XX = Female, XY = Male • Karyotype - chromosomes are arranged according to shape and size

  2. Nondisjunction and chromosomal disorders • Nondisjunction – failure of chromosomes to separate and segregate into daughter cells • Nondisjunction may occur during meiosis 1 or meiosis 2 • Abnormal number of chromosomes may result

  3. Normal meiosis MEIOSIS I Replicate DNA Results of crossing-over not shown MEIOSIS II Normal monosomic gametes

  4. Nondisjunction during meiosis I MEIOSIS I Replicate DNA Non-disjunction MEIOSIS II Disomic gametes Nullisomic gametes

  5. Nondisjunction during meiosis II MEIOSIS I Replicate DNA MEIOSIS II Non-disjunction Disomic Nullisomic Monosomic Monosomic gametes

  6. EXAMPLES OF NON-DISJUNCTION

  7. AN EXTRA COPY OF CHROMOSOME 21 CAUSES DOWN SYNDROME This condition is called trisomy 21. Person with this condition suffers from the Down syndrome. Characteristic facial features: • Round face • Flattened nose bridge • Small, irregular teeth • Short stature • Heart defects

  8. Klinefelter's syndrome,47, XXY It is the most commonsexchromosome disorderand the second most common condition caused by the presence of extra chromosomes Symptoms: • Language impairment • Lanky, youthful build or rounded body type • Low levels of Testosterone and small testicles / Infertile

  9. Turner’s Syndrome (X) Common symptoms: • Short stature • swelling of the hands and feet • Broad chest and widely spaced nipples • Low hairline • Low-set ears • Reproductive sterility • Increased weight, obesity • Small fingernails • Characteristic facial features • Webbed neck

  10. What genetic disorder is this? They may have never known…

More Related