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GENETIC DISORDERS. ____________________________ –change in a gene resulting in change in genetic information. may be spontaneous or caused by a mutagen _____________________ mutations are usually not noticed ______________________________ mutations are more severe
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____________________________–change in a gene resulting in change in genetic information • may be spontaneousor caused by a mutagen • _____________________mutations are usually not noticed • ______________________________mutations are more severe • Not all mutations are bad!
______________________ • 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
__________________ • 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
__________________ • Detachment of a segment of a chromosome, and reattachment to another non-homologous chromosome. • Some genes wind up on a completely different chromosome
ANOMALIES OF CHROMOSOME NUMBER • ________________ is common in plants • Gametes don’t reduce chromosome # • Result in cells with multiple copies of the genome
ANOMALIES OF CHROMOSOME NUMBER • __________________– more common in humans • Usually lethal before or shortly after birth • Monosomic and Trisomic
_________________________ • Occurs when homologous chromosomes fail to separate after synapsis • Most nondisjunction events are lethal to the fetus
_______________________ • Results from a third copy of chromosome 21 • Called a trisomy • Individuals have 47 chromosomes in every body cell
SEX CHROMOSOME NONDISJUNCTION DISORDERS ______________________________ • Occurs when nondisjunction causes a gamete to have a missing sex chromosome (X O) • Sterile females • 1 in 10 000 live births
SEX CHROMOSOME NONDISJUNCTION DISORDERS ________________________________ • Genotype of XXY (extra sex chromosome) • Sterile males, breast development • 1 in 800 live births
X Y O XX SEX CHROMOSOME NONDISJUNCTION DISORDERS XY XX