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Non-Mendelian Genetics

Non-Mendelian Genetics. Non-Mendelian Genetics. Some traits don’t follow the simple dominant/recessive rules that Mendel first applied to genetics. Traits can be controlled by more than one gene. Some alleles are neither dominant nor recessive. Incomplete Dominance.

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Non-Mendelian Genetics

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  1. Non-Mendelian Genetics

  2. Non-Mendelian Genetics • Some traits don’t follow the simple dominant/recessive rules that Mendel first applied to genetics. • Traits can be controlled by more than one gene. • Some alleles are neither dominant nor recessive.

  3. Incomplete Dominance • One allele is not completely dominant over another. • The heterozygous phenotype is a blending of the two homozygous phenotypes. Example: four o’clock flowers • rr=red • ww=white • rw=pink (blending of the two alleles)

  4. Codominance • Two alleles are both expressed as a dominant phenotype • Coat color in cows • RR: Red • WW: White • RW: Roan, white with red spots (NOT pink!)

  5. Multiple-Allele Series • Codominance • More than two choices of alleles are present for a trait • ABO blood type has three alleles • ABO Blood types: • If both A and B are present, type is AB • Neither is recessive • Individuals can be type A, B, AB, or O (recessive)

  6. What is blood made up of? • The red blood cells • contain hemoglobin. • Red blood cells transport O2 and CO2 to and from body tissues. • The white blood cells • fight infection. • The platelets • help the blood to clot • The plasma • Fluid which contains salts and various kinds of proteins.

  7. Determining Blood Type • Protein molecules found on the surface of RBC’s and in the blood plasma determine the blood type of an individual. • Antigens are located on the surface of the red blood cells • Antibodies are in the blood plasma.

  8. What are the different blood groups? • Blood group A (IA, IA ), (IA, i)have A antigens on the surface of red blood cells and B antibodies in blood plasma. • Blood group B (IB, IB ), (IB, i) have B antigens on the surface of red blood cells and A antibodies in blood plasma.

  9. What are the different blood groups? • Blood group AB (IA, IB )have both A and B antigens on the surface of red blood cells and no A or B antibodies in blood plasma. • Blood group O (i, i) have neither A or B antigens on the surface of red blood cells but have both A and B antibodies in blood plasma.

  10. Blood transfusions – who can receive blood from whom? • The transfusion will work if a person who is going to receive blood has a blood group that doesn't have any antibodies against the donor blood's antigens.

  11. People with blood group 0 are called "universal donors" and people with blood group AB are called "universal receivers."

  12. Rh Factor • Refers to another antigen on red blood cells • Dominant trait is to have the antigen • Rh+ • Recessive trait is not to have it • Rh- • A person with Rh- blood will produce antibodies to Rh+ blood • Can be a problem in pregnancy

  13. Sex-Linked Inheritance

  14. Review • Males have an X and a Y chromosome • Females have two X chromosomes • These chromosomes determine sex, so genes located on these chromosomes are known as sex-linked genes.

  15. The X chromosome is much larger than the Y, so it carries more genes than the Y chromosome. • Disorders that are sex-linked are much more common in males, because they would only need 1 recessive allele to have the trait; rather than the two recessive alleles the females need.

  16. Hemophilia • Recessive trait • Disorder where individuals are missing the normal blood clotting protein. • Uncontrolled bleeds from minor cuts or bruises. • Female genotype: • Male genotype:

  17. Colorblindness • Recessive • Inability to see certain colors • Female genotype: • Male genotype:

  18. Duchenne Muscular Dystrophy • Recessive • Progressive weakening and loss of skeletal muscle. • Defective version of gene that codes for muscle protein • Female genotype: • Male genotype:

  19. EXAMPLES!! • A woman who is heterozygous for normal vision marries a man who is colorblind. What are the chances of them having a son or daughter who is colorblind? **NOTE: You have to use X’s and Y’s, and read the punnett square separately for boys and girls!**

  20. A woman who is homozygous for normal blood clotting marries a man who has hemophilia. What are the chances of them having a son or daughter with hemophilia?

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