Lecture%2013

Lecture%2013 - Midterm 2 graded, on third floor of Pacific...

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1 02/27/07 BILD1 - Lecture 13 1 BILD1 The Cell Prof. Lisa M. Boulanger 02/27/07 BILD1 - Lecture 13 2 Midterm 2 graded, on third floor of Pacific Hall at 2 pm CURVE posted (next slide) Discussed in Sections this week KEY posted this Sat. Regrade requests, in writing , due by Thurs., March 1 st Also posted: supplemental reading for Thursday, “The third Bond” B A C D F Midterm 2 CURVE MEAN = 79 APPROXIMATE letter grade equivalent estimates ! 02/27/07 BILD1 - Lecture 13 4 Blending vs particulate hypotheses of inheritance Character, trait, homozygous, heterozygous, phenotype, genotype Monohybrid cross: P, F1, F2 generations 4-part model to explain 3:1 phenotype ratio: Alternate versions of genes 1 form from each parent Dominant/recessive Two forms segregate during gamete formation Highlights from previous lecture: 02/27/07 BILD1 - Lecture 13 5 Highlights from previous lecture: Testcrosses Law of independent assortment From dihybrid cross probability: “AND”- multiply “OR” – add Divergence from Mendelian Genetics Linked genes Codominance Incomplete dominance Epistasis Pleiotropy Polygenic inheritance Environmental impact 02/27/07 BILD1 - Lecture 13 6 THIS LECTURE: MORE MENDEL!
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2 02/27/07 BILD1 - Lecture 13 7 Dominant traits in humans 02/27/07 BILD1 - Lecture 13 8 Human Genetics •Alleles segregate independently in meiosis •Dominant and recessive alleles exist •Family tree or pedigree used in analysis = female = male Normal = female = male Carriers (heterozygous) = marriage Helps analyze inherited disorders, determine type of alleles involved, predict risk = female = male Affected 02/27/07 BILD1 - Lecture 13 9 Pedigree Analysis • A pedigree – Is a family tree that describes the interrelationships of parents and children across generations • Pedigrees – Can also be used to make predictions about future offspring 02/27/07 BILD1 - Lecture 13 10 • Inheritance patterns of particular traits – Can be traced and described using pedigrees Ww ww ww Ww ww Ww Ww ww ww Ww WW or Ww ww First generation (grandparents) Second generation (parents plus aunts and uncles) Third generation (two sisters) Ff Ff f Ff f Ff Ff f Ff FF or Ff f FF or Ff Widow’s peak No Widow’s peak Attached earlobe Free earlobe (a) Dominant trait (widow’s peak) (b) Recessive trait (attached earlobe) 02/27/07 BILD1 - Lecture 13 11 • Many genetic disorders – Are inherited in a recessive manner • Recessively inherited disorders – Show up only in individuals homozygous for the allele • Carriers – Are heterozygous individuals who carry the recessive allele but are phenotypically normal 02/27/07 BILD1 - Lecture 13 12 Human Genetics - Pedigrees
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3 02/27/07 BILD1 - Lecture 13 13 parents are carriers Ex. Sickle cell Cystic fibrosis Husband has to also be carrier Key: Recessive genes only show phenotype when homozygous Human Genetics - Pedigrees 02/27/07 BILD1 - Lecture 13 14 Autosomal recessive genetic disorders • Cystic fibrosis – mucus buildup in the some internal organs
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Lecture%2013 - Midterm 2 graded, on third floor of Pacific...

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