Presentation on theme: "Unit 4--Genetics Chapter 14 Human Heredity. 1) Autosomes –all the chromosomes except the sex chromosomes (in humans, there are 22 pair) 2) Sex chromosomes."— Presentation transcript:
4) Nondisjunction –Failure of chromosomes to separate –May cause a variety of birth defects, including trisomy 21 or Down syndrome
Turner’s syndrome XX O Only 1 sex chromosome is present. Turner syndrome is associated with underdeveloped ovaries, short stature, webbed neck, and broad chest. Individuals are sterile, and lack expected secondary sexual characteristics. Mental retardation typically not evident.
7) Genetic disorders –Harmful effects produced by mutated genes, most are recessive and few are lethal –Example: sickle cell anemia
Normal, with malarial resistance Same as parents ; normal, no resistance; sickle-cell anemia
8) Sex-linked traits –A recessive gene on the X chromosome –Examples: color-blindness & hemophilia –Genotypes:Phenotypes: – X N Ynormal male – X n Ycolorblind – X N X N normal female – X N X n carrier female – X n X n colorblind