2. Complex Patterns of Inheritance

3. I. The Complex Patterns A. Codominance-_______________ ex: Black and white are codominant colors in a certain type of chicken. BB=black WW=white BW=checkered (both black and white)

4. Checkered Chicken

5. ex: Roan cattle are the result of codominance. Red (R) and white (W) make roan (RW).

6. B. Incomplete Dominance-____ ex: In certain plants red and white are incompletely dominant flower colors. RR=red R’R’=whiteRR’=pink

7. Incomplete Dominance in Four O’Clock Plants

8. Examples of Problems Incomplete and Codominance Web Lab

9. C. Multiple Alleles-____________ ex: blood type There are 3 possible alleles for blood type: 1. I A or A–Type A allele 2. I B or B–Type B allele→ A & B are codominant. 3. i O or O—Type O allele

10. 1. Type O—universal donor 2. Type AB—universal recipient 3. Rh factor—if present on RBC’s, then it’s +; if not present, then it’s –; named for Rhesus monkey

11. ABO protein Rh Factor protein Type A Genotypes: Type B Genotypes: Type AB Genotypes: Type O Genotypes: (no protein) Rh + Rh- (no protein) Red blood cells

12. Examples of Blood Type Problems 1. Type A (I A i o ) X Type B (I B I B ) 2. Type AB X Type B (I B i O )

13. D. Polygenic Inheritance 1. Produced by the interaction of several genes 2. Different combinations of the genes produce different phenotypes. 3. Leads to a wide variety of phenotypes

14. examples(in humans): skin tone, height, hair color, and eye color

15. Thomas Hunt Morgan E. Thomas Hunt Morgan 1. discovered the presence of linked genes (in fruit flies) 2. Linked genes are inherited together because they are on the same chromosome.

16. F. Sex-linked Traits 1. are traits controlled by genes located on the sex chromosomes 2. usually found on the X chromosome (& called X-linked) 3. Males have sex-linked traits more often than females.

17. ex: colorblindness, hemophilia Colorblindness is diagnosed by a color wheel:

18. Examples of Sex-linked Problems

19. II. Determining Genotypes A. The environment can influence the expression of a trait. ex: A plant with “tall” genes will not grow tall without enough sunlight.

20. Ex: Temperature affects coat color gene expression in some rabbits.

21. Explanation for Testcross

22. B. Testcross—BB or Bb??? 1. method for determining the genotype of a dominant individual 2. always crosses the unknown (dominant) individual with one that is known (homozygous recessive)

23. C. Carrier—also called a hybrid 1. a heterozygous individual 2. carries the recessive trait but does NOT express it

24. Practice Questions Colorblindness in humans is a mutation carried on the X chromosome. A man and woman with normal vision have a colorblind son. What are the chances their next child will be a colorblind daughter? A 100% B 75% C 50% D 0%

25. A student is studying the inheritance of human blood types. Types A and B are codominant and O is recessive to both. If a woman with blood type A and a man with blood type B would have children, what would be the largest expected percentage for offspring with blood type O? F 0% G 25% H 50% J 100%

27. Muscular dystrophy is an X-linked recessive condition that occurs in approximately one of every 3500 individuals. A woman who is a carrier of muscular dystrophy marries a man who does not have muscular dystrophy. Which of the following is an expected outcome regarding the inheritance of muscular dystrophy by their children? F Twenty-five percent of the sons would be carriers. G One hundred percent of the daughters would be carriers. H Fifty percent of the sons would have muscular dystrophy. J Seventy-five percent of the daughters would have muscular dystrophy.

28. In the Dalmatian breed of dogs, the allele for black colored spots (B) is dominant to the allele for brown-colored spots (b). Two dogs with black spots mate and produce puppies with brown spots. What are the genotypes of the parent dogs? A BB and BB B BB and Bb C bb and BB D Bb and Bb

30. Sex-linked traits weblab