BIOL 1107 1nd Edition Lecture 30Outline of Current Lecture I. Epistasis II. Polygenic Traits Outline of Current Lecture I. Sex Chromosomes II. Human InheritanceIII. PedigreeCurrent LectureI. Sex Chromosomes- Thomas Morgan- fruit fly experiment (genetics)o Normal red-eyed female + white-eyed male -> all offspring had red eyes (Red = dominant)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Sex chromosomes:o XX = girlo XY = boyo Mother always donates an X chromosome; male donates X to daughters and Y to sons o X chromosomes are much bigger (contain more genes)- What’s going on with Morgan’s flies?(Red-eyed) XRXR x XrY (white-eyed)Xr YXR XRXr XRYXR XRXr XRY(Red-eyed) XRXr x XrY (red-eyed)Xr YXR XRXR XRYXr XRXr XRY- Q: In fruit flies, white eyes are a recessive, sex-linked (X-chromosomes; Xr) characteristic. If a white-eyed female is crossed to a wild type (red-eyed; XR) male, what proportion of the male offspring should have white eyes?- A: 100% of the offspring = white eyes(White-eyed) XrXr x XRY (red-eyed)XR YXr XRXr XrYXr XRXr XrYII. Human Inheritance- Problems? Can’t manipulate in order study, long generation times, takes longtime to reach sexual maturity; lower sample sizes for genetics studies because people are having less children nowadays - Pedigree- looking and seeing what’s already known about families - Circle – female; Square- male - Monozygotic twins – identical twins; dizygotic twins – fraternal twins III. Pedigree- Pedigree- A diagram showing the lineage or genealogy of an individual and allthe direct ancestors, usually to analyze or follow the inheritance of trait.- What’s the genotype of someone? (determine using pedigree) -> potential exam question - Probability a child will have a recessive trait? ¼ -> see pedigree (on elc New PowerPoint)- Probability that child will be affected and be a son? ¼ ( ½ X ½ = ¼ )- Autosomal recessive- one of several ways that a trait, disorder, or disease canbe passed down through families. An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.o Equal number of males and females
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