Transcript Genetics-4
Genetics4.3.12,10.3.1,10. 3.2 David Barkley Taylor Turner Polygenic Inheritance Polygenic inheritance is the inheritance of a characteristic that is controlled by more than one gene. Human traits that show continuous variation include weight, height and skin color. Polygenic Inheritance This means that something simple, like skin color, is affected by more than one gene from ones parents. Each allele of a polygenic character will offer a little bit of information to the whole phenotype. Polygenic Inheritance Human skin color is a good example to visually see how more than one gene can affect appearance. Polygenic Inheritance In humans there are at least three genes coding for skin color. Each skin color gene has two forms; one form codes for high levels of melanin production, and the other form codes for low levels of melanin production Polygenic Inheritance Wheat Kernel color in wheat is determined by two gene pairs crossing individuals with the phenotype extremes yield offspring that are a 'blend' of the two parents Polygenic Inheritance When these homozygotes are crossed the offspring are all double heterozygotes AaBb two double heterozygotes are crossedhttp://staff.jccc.net/pdecell/evolution/pol ygen.html 4.3.12 Deduce the genotypes and phenotypes of individuals in pedigree charts. Pedigrees: Are used to illustrate the mode of inheritance (dominant or recessive) Give clues to the mode of inheritance of the disease Show potential threat to other family members Phenotypes: Observable and measurable charaterics in an organisms Effects of genetic coding and environment Ex: eye color Genotypes: Genetic composition of organisms With respect to the specific traits they describe Refers specifically to genetic code (environment has no effect) Type of Inheritance Autosomal Dominant Inheritance Requires only one parent to carry the dominant gene in order for children to be affected. Autosomal Recessive Inheritance Requires for both parents must carry the recessive gene for offspring to be affected. X-Linked Dominant & Recessive Inheritance More common in boys because they only need one gene A mother gives the dominant or recessive gene male offspring and the father gives the Y chromosome. Pedigree Vs. Punnett Square A punnett square is used to determine the out come of two alleles being crossed Contrarily a pedigree is used to find modes of inheritance for genetic diseases Extra Pedigree Practice www.zerobio.com/drag_gr11/pedigree/p edigree_overview.htm I’M MY OWN GRANDPA Works Cited " 10.3.2 Explain that polygenic inheritance can contribute to continuous variation using two examples, one of which must be human skin color. ." ARHicks — Just another Edublogs.org weblog. N.p., n.d. Web. 9 Feb. 2012. <http://arhicks.edublogs.org/2011/06/07/10-3-2-explainthat-polygenic-inheritance-can-contribute-to-continuous-variation-using-two-examplesone-of-which-must-be-human-skin-color/>. "Define polygenic inheritance - IB Biology Syllabus." IB Biology Syllabus Home - IB Biology Syllabus. N.p., n.d. Web. 9 Feb. 2012. <http://ibbiology.wetpaint.com/page/Define+polygenic+inheritance>. "Explain that polygenic inheritance can contribute to continuous variation - IB Biology Syllabus." IB Biology Syllabus Home - IB Biology Syllabus. N.p., n.d. Web. 9 Feb. 2012. <http://ibbiology.wetpaint.com/page/Explain+that+polygenic+inheritance+can+contribute +to+continuous+variation>. "Gene Interactions." Estrella Mountain Community College. N.p., n.d. Web. 9 Feb. 2012. <http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookgeninteract.html>. "Genetic engineering and biotechnology." IB Guides. N.p., n.d. Web. 12 Feb. 2009. <www.ibguides.com/biology/notes/genetic-engineering-and-biotechnology>. "IB Biology Syllabus." Biology for Life. N.p., n.d. Web. 9 Feb. 2012. <http://www.biologyforlife.com/course%20info/Syllabus/Syllabus.htm#Topic_10:__HL_Geneti cs>. "Polygenic inheritance." JCCC Staff and Faculty Pages. N.p., n.d. Web. 13 Feb. 2012. <http://staff.jccc.net/pdecell/evolution/polygen.html>.