Mendelian Exceptions

1. Mendelian Exceptions

2. Mendel’s Principles Revisited • Inheritance of biological _____________ is determined by individual units known as ______. • During sexual reproduction, genes are passed from parents to _________. • Two or more forms of the gene for a single _____ exist, some forms of the gene may be _________ and others may be recessive. characteristics genes offspring trait dominant

3. Mendel’s Principles Revisited • Organisms typically have ____copies of each gene, (one from each _______) • An organism’s _____ of genes (2 alleles) are segregated from each other when ________ are formed. • Alleles for different ______ usually segregate _____________ of one another. (through meiosis) • (Law of Independent Assortment) two parent pair gametes genes independently

4. Independent Assortment in Peas __ Round yellow __ Round green __ Wrinkled yellow __ Wrinkled green 9 3 3 1

5. Incomplete Dominance • In incomplete dominance, neither allele is __________ so there is a blending of ______ when two different alleles for the same trait occur together. • Colors blend together • (______________ individuals = 3rd phenotype) dominant traits heterozygous red pink white

6. Incomplete Dominance RR • In Four O’ Clocks, if you cross a red _____(which is always pure) with a white _____ (that is also always pure) , you get apink _____ (whichis always hybrid /heterozygous WW RW RW RW RW RW

7. Incomplete Dominance • In another flower, if red ____ and blue ____ flowers are crossed, they produce a 3rd purple ____ flower • What would be the genotype ratio and phenotype ratio if you crossed two purple flowers? RR BB RB

8. Incomplete Dominance • Cross of two purple flowers____ X ____ • What are gamete possibilities? • genotype ratio 1RR : 2RB : 1BB • phenotype ratio 1red : 2 purple : 1 blue • Can you have a heterozygous red orhybrid blue flower? ___ RB RB R B RR RB R red purple BB RB B purple blue no

9. Familial Hypercholesterolemia • FF = cholesterol about 200 mg/dL • Ff = cholesterol about 400 mg/dL • ff = cholesterol about 800 mg/dL • Ff have heart attacks in 20’s • ff have heart attacks as children • What type of inheritance is this?

10. Familial Hypercholesterolemia • F is allele for receptors in the liver that remove excess cholesterol from the blood • FF makes enough receptors removes the right amount of cholesterol • Ff only makes half the needed receptors • ff makes no receptors • This trait represents incomplete dominance

11. Problem • Tom is a 21 year old college student. His father died of a heart attack at age 25. • Tom is a vegetarian and eats no junk food. He has a fasting cholesterol of 435. • Tom’s wife, Mary, has a fasting cholesterol of 177. • They are contemplating having children • What is the chance they will have a child with abnormal cholesterol?

12. FF = 200 Ff = 400 ff = 800 FF FF Ff Ff F F F f 50% chance for abnormal cholesterol

13. California Court Case • 1946 the California supreme court ruled that Charlie Chaplin was the biological father of child he claimed was not his. • His defense was that the baby had type B blood. He had type A and the woman who sued him had type O (These may not be the actual blood types, but it illustrates the point) • Was the court correct?

14. AA, AO = Type A BB, BO = Type B AB = Type AB OO = Type O AO AO OO OO O O A O The judge should take a course in genetics!

15. Codominance alleles • Both _______ contribute to the phenotype of the organism by showing up simultaneously (at the same time) in heterozygous individuals. • In cattle and horses, if you cross a pure ____ (RR) with a pure ______ (WW), you get (RW) which produces the color _____. red white roan

16. Codominance • These cattle or horses actually have both red and white hairs intermixed, or are spotted. Roan is a third ___________. • If you cross a roan with a white… phenotype R W RW WW W roan white RW WW W roan white

17. Codominance • Andalusian chickens also show this pattern of inheritance. • If you cross a black (BB) chicken • With a white (WW) chicken • You get black+white speckled (BW) chicken

18. Multiple Alleles • In this pattern of inheritance, the genes have more than _____ alleles controlling them and are therefore said to have multiple alleles. No individual has more than _____ alleles, but there are more than _____ possible alleles in a population, so a ______ will be expressed in more than two forms. two two two trait

19. Multiple Alleles • Blood type in humans is an example of this inheritance pattern. • The ______ different blood groups: • A, B, O, and AB • Are produced by ______ different alleles: • A, B, and O four three

20. Multiple Alleles • Examples of Blood type crosses

21. Multiple Alleles • Blood Groups Antigen on Red Blood Cell Safe Transfusions Phenotype (Blood Type Genotype From To

22. Multiple Alleles rabbit • The example of _______ hair color, which has at least four different alleles, is seen in these different Rex rabbits.

23. Polygenic Traits • Traits controlled by two or more genes • Show a wide range of phenotypes • The phenotype is produced by the interaction of more than ________ of genes. 1 pair

24. Polygenic Traits polygenic • These are called ___________ traits, which means “having _______ genes”. • In humans, _____ color, • _____ color, many eye skin

25. Polygenic Traits polygenic • These are called ___________ traits, which means “having _______ genes”. • In humans, _____ color, • _____ color, • and _____ color many eye skin hair

26. Polygenic Traits polygenic • These are called ___________ traits, which means “having _______ genes”. • In humans, _____ color, • _____ color, • and _____ color • are just a few of the many traits __________ by many genes. many eye skin hair controlled

27. James Bond Height Chart Polygenic Traits • Sometimes the combination of the different genes results in continuous __________ of these traits. • The combined size of all the ______ parts from head to foot, determines the _______ of the person. variation body height

28. Epistasis • One gene affects the expression of another • H allele • Produces protein for A and B antigens to attach to red blood cells • h allele • Protein has wrong shape and cannot attach to A and B antigens • A and or B antigens will fall off. • hh genotype + genotype for A,B or AB blood will have type O blood • Recessive epistasis in Labrador Retrievers

29. Penetrance • 100% • Everyone with the allele for a trait will have the trait • Less than 100% • Some individuals with the allele will not express the trait • Due to interactions of other genes

30. Polydactyle Ben Normal Bill Mark Tony Frank John Incomplete Penetrance for Polydactylism Adam Joe Don Bill did not express polydactylism

31. Expressivity • Symptoms vary in intensity in different people • Due to gene interaction • Number of extra digits varies in people with polydactylism

32. Phenocopy • Trait caused by the environment that is similar to an inherited trait • Thalidomide causes symptoms of inherited phocomelia

33. Deafness • May be caused by 132 different recessive genes • Man has aa for deafness on chromosome 1 & BB for normal hearing on chromosome 5 • Woman has bb for deafness on chromosome 5 & AA for normal hearing on chromosome 1 • What is the chance their children will inherit deafness?

34. BB = Normal Bb = normal bb = deaf AA = Normal Aa = normal aa = deaf Aa Bb Bb Aa Aa Bb Bb Aa b b a a B A B A 0% chance for deafness

35. Mitochondria • Release energy from food • Have their own DNA • Mitochondrial DNA • Many copies in each motochondrion • Mutate faster than nuclear DNA • Exposed to oxygen free radicals • No DNA repair enzymes

36. Mitochondria • Similar to DNA of prokaryotic cells • Prokaryotic cells • Engulfed into eukaryotic cells in ancient times • Have enzymes to release much more energy from food

37. Only nucleus of sperm enters oocyte. The baby will get all mitochondia from his mother. Mitochonria Oocyte

38. Mitochondrial Traits Only inherited from mother

39. Mitochondrial DNA • 37 genes • Used for metabolic reactions that release energy from food • Mitochondrial myopathies • Weak muscles • Cannot produce enough energy