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Which of these differences is controlled by genes?
Epistasis- Phenotype from one allele depends of the allele present at another gene locus
Two gene pairs interact to govern coat color in Labrador retrievers
Gene locus with alleles E or e determines where or not coat pigment is produced
Gene locus with alleles B or b determines coat color
Which allele at each locus is dominant?
Human eye color
An individual with brown and blue alleles of the bey2 gene
on chromosome 15. There are two copies of chromosome 15.
Each copy has the bey2 gene. On one copy the bey2 gene is
in the brown allele, in the other the bey2 gene is in the blue
allele. The difference between the brown and blue alleles is
due to some difference in the genetic code for each gene (the DNA
sequence for the bey2 gene isn't yet known).
Quantitative Traits- Controlled by more than one gene loci, each acting independently
Result in continuous variation in the trait
10 gene loci affect a trait
Pedigree of a family affected by alcoholism.
Disease determined by genes
Karyotype analysis
Cystic Fibrosis- recessive disorder
In vitro Fertilization Procedure
Eight cell embryo
Each cell called a blastomere
All are identical up to 8 cell stage
Preimplantation genetic diagnosis
2 blastomeres are removed for chromosome or genetic tests
Examples of genetic tests on
blastomeres
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Sex
Trisomies- extra chromosomes
Huntington’s Disease
Cystic fibrosis
Sickle cell anemia
Thallacemia
• http://www.ornl.gov/sci/techresources/Hum
an_Genome/posters/chromosome/chooser.s
html
• http://www.ornl.gov/sci/techresources/Hum
an_Genome/posters/chromosome/omim.sht
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