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Beyond Mendel

Beyond Mendel. Into the Genetic Frontier. Genes can be inherited based on various patterns. Mendel’s Dominance vs. Recessive Incomplete dominance Co-dominance Multiple alleles Polygenic genes. G. G. G. g. GG. Gg. Homozygous dominant Genotype = GG. Heterozygous Genotype = Gg.

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Beyond Mendel

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  1. Beyond Mendel Into the Genetic Frontier

  2. Genes can be inherited based on various patterns • Mendel’s Dominance vs. Recessive • Incomplete dominance • Co-dominance • Multiple alleles • Polygenic genes

  3. G G G g GG Gg Homozygous dominant Genotype = GG Heterozygous Genotype = Gg

  4. g g gg Homozygous recessive Genotype = gg

  5. Incomplete Dominance • In this pattern neither allele is considered recessive • @Heterozygous conditions produce a blend of the two traits creating a third phenotype@.

  6. Co-dominance • In this pattern much like incomplete dominance, neither allele is considered recessive • @In a heterozygous condition where each type of allele is present the phenotype displays both traits from each allele@ • There are 3 possible phenotypes

  7. Multiple alleles • @In this pattern there is more than just two alleles@(3 or more) • Combinations of other patterns • Ex. Some alleles behave in a dominant/recessive fashion while other alleles display a co-dominant or incomplete dominant relationship • This can lead to multiple phenotypes

  8. There are 4 Human Blood Types • A, B, AB & O = 4 phenotypes • Blood type is controlled by one gene, with 3 different alleles – A, B and O • The 3 alleles can be combined to produce 6 different genotypes AA BB AO BO AB OO

  9. Inheritance of Blood Type • Is a mix of complete dominance and codominance - AA & AO produce type A blood - BB & BO produce type B blood - AB produces type AB blood - OO produces type O blood From this we can infer that both A & B alleles are dominant to the O allele The A allele is codominant with the B allele

  10. Notating Blood Type IA= A allele IB = B allele i = O allele Example a person who heterozygous for A blood = IA i And a person with O blood = i i Determining Possible Outcomes • How would a person who is homozygous for B blood be notated? - IB IB • How would a person who is heterozygous for B blood be notated? - IB i

  11. What exactly is blood type? • Each blood type is the result of a specific combination of proteins found on the blood cells called antigens and proteins found in the blood plasma called antibodies - type A blood = A antigens & B antibodies - type B blood = B antigens & A antibodies - type AB blood = both A & B antigens & no antibodies - type O blood = no antigens & both A & B antibodies

  12. Why is Blood Typing Important? • If a person is given blood with antigens that their blood plasma contains antibodies for, the antibodies will attach to the blood causing it to clump - this clumping is called agglutination

  13. O is the Universal Donor AB is the Universal Recipient

  14. Polygenic traits • @Some traits which have many possible phenotypes are controlled by more than one gene.@ - the interactions of these genes allows for the large numbers of phenotypes. - human examples: Hair, eye and skin color

  15. The Inheritance of Eye Color • Only partially understood. • at least 3 different genes with 2 alleles each are responsible for eye color. – bey 1 bey 2 and gey • These genes code for the formation of the pigment melanin • The function of only 2 of the 3 genes is currently understood

  16. The Inheritance of Eye Color as it is Currently Understood • Known as the 2 gene model • One gene known as bey 2 has 2 alleles B for brown eyes and b for blue eyes • The other gene known as geyhas 2 alleles G codes for green eyes and g for blue eyes

  17. The 2 Gene Model - B is dominant to all other alleles- BBGG,BBGg,BBgg,BbGG BbGg,Bbgg=Browneyes - G is dominant to b bbGG, bbGg= Green eyes - bbggonly = blue eyes

  18. Genes and the Environment • @The characteristics of any organism are not determined solely by the genes that organism inherits.@ • Genes provide a plan for development, but how that plan unfolds also depends on the environment. • The phenotype of an organism is only partly determined by its genotype.

  19. Environment Can Influence Gene Expression example: Siamese cats - Siamese coloring is a partial albinism. Most of the cat is white -Black fur is only expressed in areas where the temperature is lower than the rest of the body - if black hair is shaved and the area kept warm then the hair that grows back will be white - if white hair is shaved and the area is cooled, then the hair will grow back black

  20. http://biologycorner.com/worksheets/genetics_codominance.html#.Ut3cORDnaUkhttp://biologycorner.com/worksheets/genetics_codominance.html#.Ut3cORDnaUk

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