genetics-4.3.12,10.3.1,10.3.2
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Genetics-4.3.12,10.3.1,10.3.2. 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. . - PowerPoint PPT PresentationTRANSCRIPT
Genetics-4.3.12,10.3.1,10.3.2David BarkleyTaylor 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 InheritanceWheatKernel color in wheat is
determined by two gene pairscrossing 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 crossed-http://staff.jccc.net/pdecell/evolution/polygen.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/pedigree_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-explain-that-polygenic-inheritance-can-contribute-to-continuous-variation-using-two-examples-one-of-which-must-be-human-skin-color/>.
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"Polygenic inheritance." JCCC Staff and Faculty Pages. N.p., n.d. Web. 13 Feb. 2012. <http://staff.jccc.net/pdecell/evolution/polygen.html>.