Mendelian Exceptions

1. Mendelian Exceptions • Chapter 12 • Section 4

2. Mendel’s Principles Revisited characteristics • 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. genes offspring trait dominant

3. Mendel’s Principles Revisited two • 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) parent pair gametes genes independently

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

5. 1.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 • 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 RR 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. 2.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

9. 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

10. 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

11. 3.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

12. 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

13. Multiple Alleles • Examples of Blood type crosses

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

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

16. 4. 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

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

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

19. Polygenic Traits polygenic many • 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. eye skin hair controlled