1. CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry Cain Wasserman Minorsky Jackson Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 11 Mendel and the Gene Idea

2. © 2014 Pearson Education, Inc.

4. Figure 11.1

5. © 2014 Pearson Education, Inc. Concept 11.1: Mendel used the scientific approach to identify two laws of inheritance  Mendel discovered the basic principles of heredity by breeding garden peas

6. © 2014 Pearson Education, Inc. Figure 11.2 Parental generation (P) Stamens First filial generation offspring (F 1 ) Carpel Technique Results 1 2 3 4 5

7. © 2014 Pearson Education, Inc.  Mendel chose characters that occurred in two distinct forms and created true-breeding lineages

8. © 2014 Pearson Education, Inc.  Mendel mated two contrasting, true-breeding varieties, (hybridization)  parents are the P generation  offspring of the P generation are called the F 1 generation  F 1 individuals self-pollinate or cross- pollinate with other F 1, producing the F 2 generation

9. © 2014 Pearson Education, Inc. Figure 11.3-1 P Generation Experiment (true-breeding parents) Purple flowers White flowers

10. © 2014 Pearson Education, Inc. Figure 11.3-2 P Generation Experiment (true-breeding parents) F 1 Generation (hybrids) Purple flowers White flowers All plants had purple flowers Self- or cross-pollination

11. © 2014 Pearson Education, Inc. Figure 11.3-3 P Generation Experiment (true-breeding parents) F 1 Generation F 2 Generation (hybrids) Purple flowers White flowers All plants had purple flowers Self- or cross-pollination 705 purple-flowered plants 224 white-flowered plants

12. © 2014 Pearson Education, Inc. Table 11.1

13. © 2014 Pearson Education, Inc. Table 11.1a

14. © 2014 Pearson Education, Inc. Table 11.1b

15. © 2014 Pearson Education, Inc. Mendel’s Model  Mendel’s model to explain the 3:1 F 2 ratio  1, alternative alleles account for variations in inherited characters  2, for each character an organism inherits two alleles, one from each parent  3, dominant alleles may mask recessive alleles  4, (law of segregation), the two alleles segregate during gamete formation (and end up in different gametes) 

16. © 2014 Pearson Education, Inc. Figure 11.5-1 P Generation Gametes: Appearance: Genetic makeup: Purple flowers PP White flowers pp P p

17. © 2014 Pearson Education, Inc. Figure 11.5-2 P Generation Gametes: Appearance: Genetic makeup: F 1 Generation Purple flowers PP White flowers pp Gametes: Appearance: Genetic makeup: ½ ½ Purple flowers Pp P P p p

18. © 2014 Pearson Education, Inc. Figure 11.5-3 P Generation Gametes: Appearance: Genetic makeup: F 1 Generation F 2 Generation Purple flowers PP White flowers pp Gametes: Appearance: Genetic makeup: Eggs from F 1 (Pp) plant Sperm from F 1 (Pp) plant ½ ½ Purple flowers Pp P P p p P p P p PP pp Pp 3 : 1

19. © 2014 Pearson Education, Inc.  Phenotype - physical appearance  genotype - genetic makeup

20. © 2014 Pearson Education, Inc. Figure 11.6 Phenotype 1 Genotype Purple White Ratio 3:1 PP (homozygous) Pp (heterozygous) Pp (heterozygous) pp (homozygous) Ratio 1:2:1 2 3 1 1

21. © 2014 Pearson Education, Inc. Test Cross Used to tell genotype of individual with dominant phenotype dominant phenotype crossed with recessive phenotype Examining offspring determines genotype of dominant individual

22. © 2014 Pearson Education, Inc. Figure 11.7 Technique Predictions Dominant phenotype, unknown genotype: PP or Pp? Eggs Sperm ½ offspring purple and ½ offspring white Recessive phenotype, known genotype: pp If purple-flowered parent is PP If purple-flowered parent is Pp Eggs Sperm All offspring purple Results or p p P p Pp pp Pp pp p p P P Pp

23. © 2014 Pearson Education, Inc. Figure 11.8 YRyr YR yr YYRR yyrr YyRr Experiment Predictions P Generation F 1 Generation Predicted offspring in F 2 generation Gametes YYRR yyrr YyRr Results Eggs Sperm or Hypothesis of dependent assortment Phenotypic ratio 3:1 Hypothesis of independent assortment ¾ ¼ ½ ½ ½ ½ ¼ ¼ ¼ ¼ ¼¼ ¼ ¼ YR yr Phenotypic ratio approximately 9:3:3:1 Phenotypic ratio 9:3:3:1 YR yr YR yr YYRR yyrr YYRr YyRr YryR Yr yR YyRR YYRrYYrr Yyrr YyRr YyRRYyRr yyRr yyRR YyRrYyrr yyRr 315108 10132 9 16 3 16 1 16

24. © 2014 Pearson Education, Inc.  Mendel’s law of independent assortment  each pair of alleles segregates independently of each other pair of alleles during gamete formation  applies to genes on different, nonhomologous chromosomes or those far apart on the same chromosome

25. © 2014 Pearson Education, Inc. Degrees of Dominance  Complete dominance  incomplete dominance  codominance

26. © 2014 Pearson Education, Inc. Figure 11.10-1 P Generation Gametes White C W Red C R CWCW CRCR

27. © 2014 Pearson Education, Inc. Figure 11.10-2 ½ ½ P Generation F 1 Generation Gametes White C W Pink C R C W Red C R CWCW CRCR CWCW CRCR

28. © 2014 Pearson Education, Inc. Figure 11.10-3 Eggs ½ ½ ½ ½ P Generation F 1 Generation Gametes F 2 Generation Gametes Sperm White C W Pink C R C W Red C R CWCWCWCW CRCWCRCW CRCRCRCR CWCW CRCR CWCW CRCR ½½ CWCW CRCR CWCW CRCR CRCWCRCW

29. © 2014 Pearson Education, Inc. Multiple Alleles  Most genes exist in populations in more than two allelic forms  For example, the four phenotypes of the ABO blood group in humans are determined by three alleles of the gene: I A, I B, and i.  The enzyme (I) adds specific carbohydrates to the surface of blood cells  The enzyme encoded by I A adds the A carbohydrate, and the enzyme encoded by I B adds the B carbohydrate; the enzyme encoded by the i allele adds neither

30. © 2014 Pearson Education, Inc. Figure 11.11 Carbohydrate (b) Blood group genotypes and phenotypes Allele Red blood cell appearance Genotype none B A IBIB Phenotype (blood group) i IAIA IAIBIAIB ii I A I A or I A i I B I B or I B i B A O AB (a) The three alleles for the ABO blood groups and their carbohydrates

31. © 2014 Pearson Education, Inc. Extending Mendelian Genetics for Two or More Genes  Some traits may be determined by two or more genes

32. © 2014 Pearson Education, Inc. Figure 11.12 ¼ ¼ ¼ ¼ ¼ ¼ ¼¼ BE Be BE be BBEE bbee BbEE BbEe bEbe bE Be BBEe BbEEbbEE bbEe BbEe BBEeBbEeBbeeBBee BbEebbEe Bbee 9 : 4 : 3 Eggs Sperm BbEe

33. © 2014 Pearson Education, Inc. Polygenic Inheritance  Quantitative variation usually indicates polygenic inheritance,  Skin color in humans is an example of polygenic inheritance

34. © 2014 Pearson Education, Inc. Figure 11.13 Eggs Sperm AaBbCc Phenotypes: 0 Number of dark-skin alleles: 12 3 4 5 6 1 64 6 64 1 64 15 64 20 64 1 8

35. © 2014 Pearson Education, Inc. Fig. 11-20, p.181 Describing Continuous Variation

36. © 2014 Pearson Education, Inc. Nature and Nurture: The Environmental Impact on Phenotype  Sometimes the phenotype depends on environment as well as genotype

37. © 2014 Pearson Education, Inc. Temperature Effects on Phenotype This Rabbit is homozygous for allele producing heat-sensitive version of an enzyme in melanin-producing pathway Melanin is produced in cooler areas of body Figure 11.16 Page 179

38. © 2014 Pearson Education, Inc. This Siamese cat, raised in a cold environment in Moscow in the late 20s, developed a relatively dark coat. An area on his shoulder was shaved, and the cat wore a warm jacket while the fur was growing back. When the shaved hair grew back in, it was white, the same color as the cat's belly, due to the increased temperature under the jacket. This was not due to scarring, as the hair grew in normally colored later.

39. © 2014 Pearson Education, Inc.

40. Figure 11.14 WW or Ww ww Ww No widow’s peak Widow’s peak wwWw 1st generation (grandparents) 3rd generation (two sisters) 2nd generation (parents, aunts, and uncles) Affected male Affected female MaleFemale Key Mating Attached earlobe Free earlobe Offspring, in birth order (first-born on left) FF or Ff ff Ff ff FfFF or Ff ffFf (a) Is a widow’s peak a dominant or recessive trait? (b) Is an attached earlobe a dominant or recessive trait?

41. © 2014 Pearson Education, Inc. Figure 11.15 Parents Sperm Normal Aa Normal Aa Eggs AA Normal Aa Normal (carrier) Aa Normal (carrier) aa Albino A a Aa

42. © 2014 Pearson Education, Inc. Sickle-Cell Disease: A Genetic Disorder with Evolutionary Implications  Sickle-cell disease affects one out of 400 African- Americans  Recessive trait caused by a single amino acid substitution of in hemoglobin  Symptoms include physical weakness, pain, organ damage, and even paralysis  Heterozygotes -less susceptible to malaria parasite,

43. © 2014 Pearson Education, Inc. Fig. 12-5, p.190 Autosomal Dominant Inheritance example… Achondro- plasia

44. © 2014 Pearson Education, Inc. Achondroplasia  Autosomal dominant allele  Homozygous usually leads to stillbirth  Heterozygotes display a type of dwarfism  (short arms and legs relative to other body parts)

45. © 2014 Pearson Education, Inc. Huntington Disorder  Autosomal dominant allele  Causes involuntary movements, nervous system deterioration, death  Symptoms appear after age 30  People often pass allele on before they know they have it

46. © 2014 Pearson Education, Inc. Huntington Disorder

47. © 2014 Pearson Education, Inc. Hutchinson-Gilford Progeria  Mutation causes accelerated aging  No evidence of it running in families  Appears dominant  Seems to arise as spontaneous mutation  Usually causes death in early teens

48. © 2014 Pearson Education, Inc. Fig. 12-7, p.191 Hutchinson-Gilford Progeria

49. © 2014 Pearson Education, Inc. The Y Chromosome  Fewer than two dozen genes identified  SRY gene (sex-determining region of Y) is the master gene for male sex determination

50. © 2014 Pearson Education, Inc. Fig. 11-21, p.183

51. © 2014 Pearson Education, Inc. Fig. 11-21, p.183

52. © 2014 Pearson Education, Inc. If you see 6th hr students You can warn them about This pop quiz, just don’t Tell them it’s a participation Grade – give them a little thrill To end their schoolday with