1 / 12

GENETIC DISORDERS

GENETIC DISORDERS. Mutation –change in a gene resulting in change in genetic information. may be spontaneous or caused by a mutagen Somatic mutations are usually not noticed Gametic mutations are more severe Not all mutations are bad !. SINGLE-GENE DEFECTS.

reba
Download Presentation

GENETIC DISORDERS

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. GENETIC DISORDERS

  2. Mutation –change in a gene resulting in change in genetic information • may be spontaneousor caused by a mutagen • Somatic mutations are usually not noticed • Gametic mutations are more severe • Not all mutations are bad!

  3. SINGLE-GENE DEFECTS • Misplacement, insertion or deletion of one base pair • May result in incorrect amino acid • May result in shift of reading frame • Congenital Defects: • Visible at birth(club foot, spina bifida, congenital heart defects) • Caused by environmental factors (FAS, German measles) • Inherited • Sickle Cell Anemia, Cystic Fibrosis

  4. INVERSIONS • Part of chromosome is flipped around 180° from its normal orientation. • Happens when chromosome breaks occur. • Broken piece may reattach, but not necessarily in the same orientation as before

  5. TRANSLOCATIONS • Detachment of a segment of a chromosome, and reattachment to another non-homologous chromosome. • Some genes wind up on a completely different chromosome

  6. ANOMALIES OF CHROMOSOME NUMBER • Polyploidy is common in plants • Gametes don’t reduce chromosome # • Result in cells with multiple copies of the genome

  7. ANOMALIES OF CHROMOSOME NUMBER • Aneuploidy – more common in humans • Usually lethal before or shortly after birth • Monosomic and Trisomic

  8. NONDISJUNCTION • Occurs when homologous chromosomes fail to separate after synapsis • Most nondisjunction events are lethal to the fetus

  9. DOWNS SYNDROME • Results from a third copy of chromosome 21 • Called a trisomy • Individuals have 47 chromosomes in every body cell

  10. SEX CHROMOSOME NONDISJUNCTION DISORDERS TURNER SYNDROME • Occurs when nondisjunction causes a gamete to have a missing sex chromosome (X O) • Sterile females • 1 in 10 000 live births

  11. SEX CHROMOSOME NONDISJUNCTION DISORDERS KLINEFELTER’S SYNDROME • Genotype of XXY (extra sex chromosome) • Sterile males, breast development • 1 in 800 live births

  12. X Y O XX SEX CHROMOSOME NONDISJUNCTION DISORDERS XY XX

More Related