COMPLEX TRAITS Polygenic Traits Determined by more than one gene. Height, skin eye color are polygenic See Fig 24.8, page 929 and 24.9 page 930. Multifactorial Traits Determined by more than one gene (polygenic) and environment. Height is Multifactorial because it is polygenic plus nutrition plays a role See Fig 24.8, page 929 and 24.9 page 930. V. MATTERS OF SEX Sex Determination: See Fig 24.11, page 931. In sexually reproducing animals, two of chromosomes exist: Most pairs are called autosomes which determine most traits; One pair represents the sex chromosomes, which determine sex of the individual. Female = XX; Male = XY. See Fig 24.14, page 935. Following gametogenesis (sex cell formation; meiosis): In females, the ova (gametes) contain 22 autosomes and the X sex chromosome. All ova contain the X chromosome. XX  X (ova) In males, the sperm contain 22 autosomes, but half the sperm carry the X sex chromosome and the other half of the sperm contain the Y sex chromosome: XY  X or Y (sperm) During fertilization, the chance of: an X sperm and the X ova fusing to produce a female (XX) is 50%; a Y sperm and the X ova fusing to produce a male (XY) is 50%. V. MATTERS OF SEX
COMPLEX TRAITS Polygenic Traits Determined by more than one gene. Height, skin eye color are polygenic See Fig 24.8, page 929 and 24.9 page 930. Multifactorial Traits Determined by more than one gene (polygenic) and environment. Height is Multifactorial because it is polygenic plus nutrition plays a role See Fig 24.8, page 929 and 24.9 page 930. V. MATTERS OF SEX Sex Determination: See Fig 24.11, page 931. In sexually reproducing animals, two of chromosomes exist: Most pairs are called autosomes which determine most traits; One pair represents the sex chromosomes, which determine sex of the individual. Female = XX; Male = XY. See Fig 24.14, page 935. Following gametogenesis (sex cell formation; meiosis): In females, the ova (gametes) contain 22 autosomes and the X sex chromosome. All ova contain the X chromosome. XX  X (ova) In males, the sperm contain 22 autosomes, but half the sperm carry the X sex chromosome and the other half of the sperm contain the Y sex chromosome: XY  X or Y (sperm) During fertilization, the chance of: an X sperm and the X ova fusing to produce a female (XX) is 50%; a Y sperm and the X ova fusing to produce a male (XY) is 50%. V. MATTERS OF SEX
Ch24%20Genetics%20and%20Genomics.docx