Download Gentetics 4. polygenic traits and multiple alleles.notebook

Gentetics 4. polygenic traits and multiple alleles.notebook
January 10, 2017
Aim : other factors affecting the expression of traits.
Genetics homework : Read section 11.3 and answer questions 1 and 2. Finish problems worksheet­ Sex linked and influence of environment. Unit test 1/17 E day. 1. Quiz
2. Explanation of multipe alleles and
polygenic traits.
3. Sex linked inheritance.
4. Work on problems
• Polygenic traits (most common in nature)
Aim
Polygenic traits: • Some traits are controlled by the interaction of several genes .
This traits often show a great range of phenotypes in the
population. For example the human population skin color, and
human height.
Dihybrid cross
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Gentetics 4. polygenic traits and multiple alleles.notebook
January 10, 2017
• Gene Linkage:
When genes for 2 different traits are located very close in
the same chromosome they usually are inherited together. They seem to violate the law of independent assortment.
examples include: Jan 11­1:04 PM
• Genes and environment (epigenetics):
The environment plays a role in the way a gene is expressed in an organism. Exampl
Fur color in hares
Jan 7­9:53 AM
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Gentetics 4. polygenic traits and multiple alleles.notebook
January 10, 2017
Sex linked inheritance:
Are mutations that occur on the genes in the X chromosome, therefore they affect more males than females.
Disorders include:
Hemophilia (inability of blood to clot)
Red green colorblindness
XX= Female
Xy = male
Fix the mistakes in the pedigree diagram so that it fits inheritance of a sex linked disease. Jan 4­6:56 PM
Summary of our current understanding of Mendel laws Traits are determined by genes (factors) that are passed from parents to offspring in their sex cells. Some traits are dominant other are recessive ( F1) Mono hybrid cross • Most traits are controlled by 2 genes one from each parent. They segregate as gametes form (egg and sperm) form, and recombine during fertilization (F2)
Law of independent assortment. What was the evidence?
• The genes for different traits usually segregate independently of one another. (demonstrated with dihybrid crosses)
What are the other patterns of inheritance? • incomplete dominance
• codominance
• Polygenic traits
• Linked genes
Summary of Mendel Laws.
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Gentetics 4. polygenic traits and multiple alleles.notebook
January 10, 2017
Jan 10­12:28 PM
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