2. EOC Review Chapter 11

3. What is genetics? The scientific study of heredity

4. Question: What is Heredity?

5. Answer: The passing of characteristics or traits from parents to offspring… Examples of traits: hair color eye color presence of freckles height

6. Gregor Mendel. Became a monk at a monastery in 1843. Taught biology and had interests in statistics. Also studied at the University of Vienna

7. continued After returning to the monastery he continued to teach and worked in the garden. Between 1856 and 1863 he grew and tested over 28,000 pea plants

8. Mendel’s Peas Easy to grow. Easily identifiable traits Can work with large numbers of samples

9. Question: Why did Mendel use peas?

10. Answer: They were ‘true breeding’ meaning they were self pollinating reproducing asexually…

11. Mendel’s experiments The first thing Mendel did was create a “pure” generation or true-breeding generation. He made sure that certain pea plants were only able to self pollinate, eliminating unwanted traits. He did this by cutting away the stamen, or male part of each flower

12. Genes and dominance Trait : a characteristic Mendel studied seven of these traits After Mendel ensured that his true- breeding generation was pure, he then crossed plants showing contrasting traits. He called the offspring the F1F1 generation or first filial.

13. What will happen when pure yellow peas are crossed with pure green peas? All of the offspring were yellow. Hybrids = the offspring of crosses between parents with contrasting traits

14. What did Mendel conclude? Inheritance is determined by factors passed on from one generation to another. Mendel knew nothing about chromosomes, genes, or DNA. Why? These terms hadn’t yet been defined. Know: Hybrids = Heterozygous

15. What were Mendel’s “factors” The ‘factors” that Mendel mentioned were the genes. Each gene has different forms called alleles Mendel’s second principle stated that some alleles are dominant and some are recessive.

16. Question: Distinguish traits from alleles…

17. Answer: Traits are categories: height, weight, eye color, hair type Alleles are within categories: tall, fat, blue eyes, wavy hair… ***So alleles are specific descriptions of traits: KNOW THIS!!!

18. Mendel’s second cross He allowed the F 1 generation to self- pollinate thus producing the F 2 generation. Did the recessive allele completely disappear? What happened when he crossed two yellow pea hybrid (F 1 ) plants?

19. Results: ¾ of the peas were yellow, ¼ of the peas were green. So this could be written as 3 out of 4, or 75% and 25%...

20. Probability The likelihood of a particular event occurring. A random Chance… Can be expressed as a fraction or a percent. ***Example: coin flip The chance of rolling a 2 on the 1 st roll is 1 out of 2, ½ or 50%...

21. Punnett Square Developed by Reginald Punnett. A diagram used to show the probability or chances of a certain trait being passed from one generation to another.

22. Reading Punnett squares Gametes are placed above and to the left of the square Offspring are placed in the square. Capital letters (Y) represent dominant alleles. Lower case letters (y) represent recessive alleles.

23. Punnett square example What percent is yellow…Green? Make a ratio of yellow to green?? Hint: Any capital letter expresses the trait- dominant

24. Homozygous = when an organism possesses two identical alleles. ex. YY or yy Heterozygous = when an organism possesses different alleles. ex. Yy

25. Phenotype vs genotype Genotype  The genetic makeup  Symbolized with letters  Tt or TT Phenotype Physical appearance of the organism Expression of the trait Short, tall, yellow, smooth, etc.

26. Punnett square review:

28. Independent Assortment The two factor cross. Example: color and shape of peas. F1 F1 cross to produce the F2 F2 generation Ex RRYY x rryy Round yellow mated with wrinkled green Offspring would all be hybrid for both traits (RrYy)

29. The dihybrid cross Punnett square on board:

30. Some exceptions to Mendel’s principles: Some alleles are neither dominant nor recessive. Many traits are controlled by more than one gene (polygenic traits)

31. Incomplete dominance A situation in which neither allele is dominant. When both alleles are present a “new” phenotype appears that is a blend of each allele. Alleles will be represented by capital letters only.

32. Japanese four-o-clock flowers Red flower plant genotype = RR White flower plant genotype = WW Pink flower plant genotype = RW

33. What happens when a red flower is crossed with a white flower? According to Mendel either some white and some red or all offspring either red or white. All are pink

34. Codominance When two alleles both appear in the phenotype. Usually signified using superscripts. example: color of hair coat in cattle. crcr crcr = red hairs cwcw cwcw = white hairs crcw crcw = roan coat (mixture of both colors)

35. Roan cattle inheritance

36. Multiple allele inheritance When two or more alleles contribute to the phenotype. Human blood types: A,B,O and AB A and B are codominant to each other. Both A and B are dominant over O.

37. Human Blood types: TYPE A Allele = I A Blood cells have small antigens on the surface.

38. TYPE B Allele = IBIB Cells coated with type B antigens

39. TYPE AB genotype = IAIBIAIB Blood cells contain both types of antigens Known as universal recipient

40. TYPE O Allele = i No antigens on the surface of the blood cells Known as universal donor

41. 6 different genotypes: Must draw several punnett squares IAIAIAIA IAIBIAIB IBIBIBIB IBiIBi IAiIAi i i Type A AB Type B B A O

42. How common are the different blood types?

43. Rh factor Studied from Rhesus monkey… ONLY IMPORTANT DURING FEMALE’S SECOND CHILD! Rh +, Rh-

44. Sample Problem: A man with type AB blood marries a woman with type B blood blood. Can they have a child with type A blood? Type AB? Hint: must do 2 punnett squares

45. Answer: Yes AB Yes B 25% A 0% O

46. Polygenic traits Traits controlled by two or more genes. Examples: Human height, eye and skin color

47. END OF GENETICS REVIEW This will be posted on Katz web page: www.katmanscience.com Under BIO EOC tab…