1. LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick Mendel and the Gene Idea Chapter 14

2. Overview: Drawing from the Deck of Genes What genetic principles account for the passing of traits from parents to offspring? The “__________” hypothesis is the idea that genetic material from the two parents blends together (like blue and yellow paint blend to make green) © 2011 Pearson Education, Inc.

3. The “______________” hypothesis is the idea that parents pass on discrete heritable units (genes) This hypothesis can explain the ___________of traits after several generations ___________ documented a particulate mechanism through his experiments with garden peas © 2011 Pearson Education, Inc.

4. Figure 14.1

5. Concept 14.1: Mendel used the scientific approach to identify two laws of inheritance Mendel discovered the basic principles of heredity by breeding _________________ in carefully planned experiments © 2011 Pearson Education, Inc.

6. Mendel’s Experimental, Quantitative Approach Advantages of pea plants for genetic study –There are many varieties with distinct heritable features, or characters (such as flower color); character variants (such as purple or white flowers) are called traits –Mating can be controlled –Each flower has sperm-producing organs (stamens) and an egg-producing organ (carpel) –Cross-pollination (fertilization between different plants) involves dusting one plant with pollen from another © 2011 Pearson Education, Inc.

7. Figure 14.2a Parental generation (P) Stamens Carpel TECHNIQUE 2134

8. Figure 14.2b First filial generation offspring (F 1 ) RESULTS 5

9. Mendel chose to track only those characters that occurred in ____________________ forms He also used varieties that were ____________ (plants that produce offspring of the same variety when they self-pollinate) © 2011 Pearson Education, Inc.

10. In a typical experiment, Mendel mated two contrasting, true-breeding varieties, a process called ____________________ The true-breeding parents are the ____________ The hybrid offspring of the P generation are called the ___________________ When F 1 individuals self-pollinate or cross- pollinate with other F 1 hybrids, the ____________ is produced © 2011 Pearson Education, Inc.

11. The Law of Segregation When Mendel crossed contrasting, true- breeding white- and purple-flowered pea plants, all of the F 1 hybrids were _____________ When Mendel crossed the F 1 hybrids, many of the F 2 plants had purple flowers, but some had _____________ Mendel discovered a ratio of about _________ ______________, purple to white flowers, in the F 2 generation © 2011 Pearson Education, Inc.

12. Figure 14.3-3 P Generation EXPERIMENT (true-breeding parents) F 1 Generation (hybrids) F 2 Generation Purple flowers White flowers All plants had purple flowers Self- or cross-pollination 705 purple- flowered plants 224 white flowered plants

13. Mendel reasoned that only the ______________ factor was affecting flower color in the F 1 hybrids Mendel called the purple flower color a _________________________ and the white flower color a recessive trait The factor for white flowers was not __________ ________________________ because it reappeared in the F 2 generation © 2011 Pearson Education, Inc.

14. Mendel observed the same pattern of inheritance in six other pea plant characters, each represented by _________________ What Mendel called a “___________________” is what we now call a ______________ © 2011 Pearson Education, Inc.

15. Table 14.1

16. Mendel’s Model Mendel developed a hypothesis to explain the ________ inheritance pattern he observed in F 2 offspring ______________ related concepts make up this model These concepts can be related to what we now know about ______ and __________________ © 2011 Pearson Education, Inc.

17. First: ________________________ of genes account for variations in inherited characters For example, the gene for flower color in pea plants exists in two versions, one for purple flowers and the other for white flowers These alternative versions of a gene are now called _______________ Each gene resides at a specific __________ on a specific chromosome © 2011 Pearson Education, Inc.

18. Figure 14.4 Allele for purple flowers Locus for flower-color gene Allele for white flowers Pair of homologous chromosomes

19. Second: for each character, an organism inherits ______________, one from each parent Mendel made this deduction without knowing about the role of chromosomes The two alleles at a particular locus may be ______________, as in the true-breeding plants of Mendel’s P generation Alternatively, the two alleles at a locus may ___________, as in the F 1 hybrids © 2011 Pearson Education, Inc.

20. Third: if the two alleles at a locus differ, then one (the _______________) determines the organism’s appearance, and the other (______________________) has no noticeable effect on appearance In the flower-color example, the F 1 plants had purple flowers because the allele for that trait is dominant © 2011 Pearson Education, Inc.

21. Fourth (now known as the ________________): the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes Thus, an egg or a sperm gets only ______ of the two alleles that are present in the organism This segregation of alleles corresponds to the distribution of ________________________ to different gametes in meiosis © 2011 Pearson Education, Inc.

22. Mendel’s segregation model accounts for the 3:1 ratio he observed in the F 2 generation of his numerous crosses The possible combinations of sperm and egg can be shown using a ____________________, a diagram for predicting the results of a genetic cross between individuals of known genetic makeup A __________________ represents a dominant allele, and a ____________________ represents a recessive allele © 2011 Pearson Education, Inc.

23. Figure 14.5-3 P Generation F 1 Generation F 2 Generation Appearance: Genetic makeup: Gametes: Appearance: Genetic makeup: Gametes: Purple flowers White flowers Purple flowers Sperm from F 1 ( Pp ) plant Pp PP pp P P P P p p p p Eggs from F 1 ( Pp ) plant PP pp Pp 1/21/2 1/21/2 3 : 1

24. Useful Genetic Vocabulary An organism with two identical alleles for a character is said to be __________________ for the gene controlling that character An organism that has two different alleles for a gene is said to be _____________________ for the gene controlling that character Unlike homozygotes, heterozygotes are not ______________________ © 2011 Pearson Education, Inc.

25. Because of the different effects of dominant and recessive alleles, an organism’s __________ do not always reveal its genetic composition Therefore, we distinguish between an organism’s ________________, or physical appearance, and its ___________________, or genetic makeup In the example of flower color in pea plants, ___ and _____ plants have the same phenotype (purple) but different genotypes © 2011 Pearson Education, Inc.

26. Phenotype Purple White 3 1 1 1 2 Ratio 3:1 Ratio 1:2:1 Genotype PP (homozygous) Pp (heterozygous) pp (homozygous) Figure 14.6

27. The Testcross How can we tell the genotype of an individual with the dominant phenotype? Such an individual could be either ____________ dominant or ___________________ The answer is to carry out a ______________: breeding the mystery individual with a homozygous recessive individual If any offspring display the __________________, the mystery parent must be heterozygous © 2011 Pearson Education, Inc.

28. Figure 14.7 Dominant phenotype, unknown genotype: PP or Pp ? Recessive phenotype, known genotype: pp Predictions If purple-flowered parent is PP If purple-flowered parent is Pp or Sperm Eggs or All offspring purple 1 / 2 offspring purple and 1 / 2 offspring white Pp pp p ppp P P P p TECHNIQUE RESULTS

29. The Law of Independent Assortment Mendel derived the law of segregation by following a ________________________ The F 1 offspring produced in this cross were ___________________, individuals that are heterozygous for one character A cross between such heterozygotes is called a _________________________ © 2011 Pearson Education, Inc.

30. Mendel identified his second law of inheritance by following ___________________ at the same time Crossing two true-breeding parents differing in two characters produces _______________ in the F 1 generation, heterozygous for both characters A ____________________, a cross between F 1 dihybrids, can determine whether two characters are transmitted to offspring as a package or independently © 2011 Pearson Education, Inc.

31. Figure 14.8 P Generation F 1 Generation Predictions Gametes EXPERIMENT RESULTS YYRR yyrr yr YR YyRr Hypothesis of dependent assortment Hypothesis of independent assortment Predicted offspring of F 2 generation Sperm or Eggs Phenotypic ratio 3:1 Phenotypic ratio 9:3:3:1 Phenotypic ratio approximately 9:3:3:1 315 108 101 32 1/21/2 1/21/2 1/21/2 1/21/2 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 9 / 16 3 / 16 1 / 16 YR yr 1/41/4 3/43/4 Yr yR YYRR YyRr yyrr YYRRYYRrYyRR YyRr YYRrYYrr YyRr Yyrr YyRR YyRr yyRR yyRr YyRr YyrryyRr yyrr

32. Using a dihybrid cross, Mendel developed the ____________________________ The law of independent assortment states that each pair of alleles ______________________ of each other pair of alleles during gamete formation Strictly speaking, this law applies only to genes on ___________________________________ or those far apart on the same chromosome Genes located near each other on the same chromosome tend to be ___________________ © 2011 Pearson Education, Inc.

33. Concept 14.2: The laws of probability govern Mendelian inheritance Mendel’s laws of segregation and independent assortment reflect the rules of _____________ When tossing a coin, the outcome of one toss has _________________ on the outcome of the next toss In the same way, the alleles of one gene segregate into gametes ______________ of another gene’s alleles © 2011 Pearson Education, Inc.

34. The ________________________ states that the probability that two or more independent events will occur together is the product of their individual probabilities Probability in an F 1 monohybrid cross can be determined using the ______________________ Segregation in a heterozygous plant is like flipping a coin: Each gamete has a chance of carrying the ___________________ and a chance of carrying the _________________________ The Multiplication and Addition Rules Applied to Monohybrid Crosses © 2011 Pearson Education, Inc.

35. Figure 14.9 Segregation of alleles into eggs Segregation of alleles into sperm Sperm Eggs 1/21/2 1/21/2 1/21/2 1/21/2 1/41/4 1/41/4 1/41/4 1/41/4 Rr R R R R R R r r r r r  r

36. The ____________________ states that the probability that any one of two or more exclusive events will occur is calculated by adding together their individual probabilities The rule of addition can be used to figure out the probability that an F 2 plant from a monohybrid cross will be ____________________ rather than _________________________ © 2011 Pearson Education, Inc.

37. Solving Complex Genetics Problems with the Rules of Probability We can apply the multiplication and addition rules to predict the outcome of crosses involving _____________________________ A dihybrid or other multicharacter cross is equivalent to two or more independent ____________ crosses occurring simultaneously In calculating the chances for various genotypes, each character is considered ________, and then the individual probabilities are ___________ © 2011 Pearson Education, Inc.

38. Figure 14.UN01 Probability of YYRR Probability of YyRR 1 / 4 (probability of YY) 1 / 2 (Yy) 1 / 4 (RR) 1 / 16 1/81/8      

39. Figure 14.UN02 Chance of at least two recessive traits ppyyRr ppYyrr Ppyyrr PPyyrr ppyyrr 1 / 4 (probability of pp)  1 / 2 (yy)  1 / 2 (Rr) 1/4  1/2  1/21/4  1/2  1/2 1/2  1/2  1/21/2  1/2  1/2 1/4  1/2  1/21/4  1/2  1/2 1/4  1/2  1/21/4  1/2  1/2  1 / 16  2 / 16  1 / 16  6 / 16 or 3 / 8

40. Concept 14.3: Inheritance patterns are often more complex than predicted by simple Mendelian genetics The relationship between genotype and phenotype is __________________ as in the pea plant characters Mendel studied Many heritable characters _________ determined by only one gene with two alleles However, the basic principles of segregation and independent assortment apply even to more complex patterns of inheritance © 2011 Pearson Education, Inc.

41. Extending Mendelian Genetics for a Single Gene Inheritance of characters by a single gene may deviate from simple Mendelian patterns in the following situations: –When alleles are not completely _____________ _____________________ –When a gene has ________________________ –When a gene produces ____________________ © 2011 Pearson Education, Inc.

42. Degrees of Dominance _____________________ occurs when phenotypes of the heterozygote and dominant homozygote are identical In ________________________, the phenotype of F 1 hybrids is somewhere between the phenotypes of the two parental varieties In ___________________, two dominant alleles affect the phenotype in separate, distinguishable ways © 2011 Pearson Education, Inc.

43. Figure 14.10-3 P Generation F 1 Generation F 2 Generation 1/21/2 1/21/2 1/21/2 1/21/2 1/21/2 1/21/2 Red White Gametes Pink Gametes Sperm Eggs CWCWCWCW CRCRCRCR CRCR CWCW CRCWCRCW CRCR CWCW CWCW CRCR CRCR CWCW CRCRCRCR CRCWCRCW CRCWCRCW CWCWCWCW

44. A dominant allelle ________________ subdue a recessive allele; alleles don’t interact that way Alleles are simply ______________ in a gene’s nucleotide sequence For any character, dominance/recessiveness relationships of alleles depend on the ________ at which we examine the phenotype The Relation Between Dominance and Phenotype © 2011 Pearson Education, Inc.

45. ___________________ is fatal; a dysfunctional enzyme causes an accumulation of lipids in the brain –At the ___________ level, the allele is recessive –At the ____________ level, the phenotype (i.e., the enzyme activity level) is incompletely dominant –At the _____________ level, the alleles are codominant © 2011 Pearson Education, Inc.

46. Frequency of Dominant Alleles Dominant alleles _____________ necessarily more common in populations than recessive alleles For example, one baby out of ______ in the United States is born with extra fingers or toes © 2011 Pearson Education, Inc.

47. The allele for this unusual trait is _____________ to the allele for the more common trait of five digits per appendage In this example, the _____________________ is far more prevalent than the population’s dominant allele © 2011 Pearson Education, Inc.

48. Multiple Alleles Most genes exist in populations in ___________ ___________________________ allelic forms For example, the four phenotypes of the ______ blood group in humans are determined by three alleles for the enzyme (I) that attaches A or B carbohydrates to red blood cells: _____________. The enzyme encoded by the I A allele adds the __ ______________, whereas the enzyme encoded by the I B allele adds the __________________; the enzyme encoded by the i allele adds _______ © 2011 Pearson Education, Inc.

49. Figure 14.11 Carbohydrate Allele (a) The three alleles for the ABO blood groups and their carbohydrates (b) Blood group genotypes and phenotypes Genotype Red blood cell appearance Phenotype (blood group) A A B B AB none O IAIA IBIB i ii IAIBIAIB I A I A or I A i I B I B or I B i

50. Pleiotropy Most genes have multiple phenotypic effects, a property called ___________ For example, pleiotropic alleles are responsible for the ___________________ of certain hereditary diseases, such as cystic fibrosis and sickle-cell disease © 2011 Pearson Education, Inc.

51. Extending Mendelian Genetics for Two or More Genes Some traits may be determined by ___________ ___________________ © 2011 Pearson Education, Inc.

52. Epistasis In _____________, a gene at one locus alters the phenotypic expression of a gene at a second locus For example, in Labrador retrievers and many other mammals, ______________ depends on two genes One gene determines the pigment color (with alleles B for black and b for brown) The other gene (with alleles C for color and c for no color) determines whether the pigment will be deposited in the hair © 2011 Pearson Education, Inc.

53. Figure 14.12 Sperm Eggs 9 : 3 : 4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 1/41/4 BbEe BE bE Be be BBEE BbEE BBEeBbEe BbEE bbEEBbEe bbEe BBEe BbEe BBeeBbee BbEebbEe Bbee bbee

54. Polygenic Inheritance _________________________ are those that vary in the population along a continuum Quantitative variation usually indicates ________ __________________, an additive effect of two or more genes on a single phenotype ___________________ in humans is an example of polygenic inheritance © 2011 Pearson Education, Inc.

55. Figure 14.13 Eggs Sperm Phenotypes: Number of dark-skin alleles: 0 12345 6 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1/81/8 1 / 64 6 / 64 15 / 64 20 / 64 15 / 64 6 / 64 1 / 64 AaBbCc

56. Nature and Nurture: The Environmental Impact on Phenotype Another departure from Mendelian genetics arises when the phenotype for a character depends on ___________ as well as genotype The ___________________ is the phenotypic range of a genotype influenced by the environment For example, ________________ flowers of the same genotype range from blue-violet to pink, depending on soil acidity © 2011 Pearson Education, Inc.

57. Figure 14.14

58. Norms of reaction are generally broadest for __________________________ Such characters are called _________________ because genetic and environmental factors collectively influence phenotype © 2011 Pearson Education, Inc.

59. Integrating a Mendelian View of Heredity and Variation An organism’s ________________ includes its physical appearance, internal anatomy, physiology, and behavior An organism’s phenotype reflects its overall ______________ and unique ________________ © 2011 Pearson Education, Inc.

60. Concept 14.4: Many human traits follow Mendelian patterns of inheritance ________________ are not good subjects for genetic research –Generation time is too long –Parents produce relatively few offspring –Breeding experiments are unacceptable However, basic Mendelian genetics endures as the foundation of human genetics © 2011 Pearson Education, Inc.

61. Pedigree Analysis A _____________ is a family tree that describes the interrelationships of parents and children across generations ________________________ of particular traits can be traced and described using pedigrees © 2011 Pearson Education, Inc.

62. Figure 14.15 Key Male Female Affected male Affected female Mating Offspring 1st generation 2nd generation 3rd generation 1st generation 2nd generation 3rd generation Is a widow’s peak a dominant or recessive trait? (a)Is an attached earlobe a dominant or recessive trait? b) Widow’s peak No widow’s peak Attached earlobe Free earlobe FF or Ff WW or Ww Ww ww Ww ww Ff ff FF or Ff ff

63. Pedigrees can also be used to make ______________________ about future offspring We can use the ______________ and __________________ rules to predict the probability of specific phenotypes © 2011 Pearson Education, Inc.

64. Recessively Inherited Disorders Many genetic disorders are inherited in a ________________ manner These range from relatively mild to life- threatening © 2011 Pearson Education, Inc.

65. The Behavior of Recessive Alleles Recessively inherited disorders show up only in individuals ________________ for the allele _________________ are heterozygous individuals who carry the recessive allele but are phenotypically normal; most individuals with recessive disorders are born to carrier parents _________________ is a recessive condition characterized by a lack of pigmentation in skin and hair © 2011 Pearson Education, Inc.

66. Figure 14.16 Parents Normal Aa Sperm Eggs Normal Aa AA Normal Aa Normal (carrier) Aa Normal (carrier) aa Albino A A a a

67. If a recessive allele that causes a disease is rare, then the chance of two carriers meeting and mating is __________ ______________________ (i.e., matings between close relatives) increase the chance of mating between two carriers of the same rare allele Most societies and cultures have laws or taboos against marriages between close relatives © 2011 Pearson Education, Inc.

68. Cystic Fibrosis ________________________ is the most common lethal genetic disease in the United States,striking one out of every 2,500 people of European descent The cystic fibrosis allele results in defective or absent ________________________ in plasma membranes leading to a buildup of chloride ions outside the cell Symptoms include __________________ in some internal organs and ____________ __________ of nutrients in the small intestine © 2011 Pearson Education, Inc.

69. Sickle-Cell Disease: A Genetic Disorder with Evolutionary Implications ___________________ affects one out of 400 African-Americans The disease is caused by the substitution of a single ______________ in the hemoglobin protein in red blood cells In _______________ individuals, all hemoglobin is abnormal (sickle-cell) Symptoms include _______________________ _____________________________ © 2011 Pearson Education, Inc.

70. Fig. 14-UN1 © 2011 Pearson Education, Inc. ___________________ (said to have sickle-cell trait) are usually healthy but may suffer some symptoms About __________________ African Americans has sickle cell trait, an unusually high frequency of an allele with detrimental effects in homozygotes Heterozygotes are less susceptible to the _________________ parasite, so there is an advantage to being heterozygous

71. Dominantly Inherited Disorders Some human disorders are caused by ________________ alleles Dominant alleles that cause a lethal disease are ___________ and arise by mutation _________________________ is a form of dwarfism caused by a rare dominant allele © 2011 Pearson Education, Inc.

72. Figure 14.17 Parents Dwarf Dd Sperm Eggs Dd Dwarf dd Normal Dd Dwarf dd Normal D d d d Normal dd

73. The _____________ of onset of a disease significantly affects its inheritance ________________________ is a degenerative disease of the nervous system The disease has no obvious phenotypic effects until the individual is about ____________ years of age Once the deterioration of the ________________ begins the condition is irreversible and fatal Huntington’s Disease: A Late-Onset Lethal Disease © 2011 Pearson Education, Inc.

74. Multifactorial Disorders Many diseases, such as heart disease, diabetes, alcoholism, mental illnesses, and cancer have both _______________________ components Little is understood about the genetic contribution to most multifactorial diseases © 2011 Pearson Education, Inc.

75. Genetic Testing and Counseling ________________________ can provide information to prospective parents concerned about a family history for a specific disease © 2011 Pearson Education, Inc.

76. Counseling Based on Mendelian Genetics and Probability Rules Using _____________________, genetic counselors help couples determine the odds that their children will have genetic disorders ____________________ are predicted on the most accurate information at the time; predicted probabilities may change as new information is available © 2011 Pearson Education, Inc.

77. Tests for Identifying Carriers For a growing number of diseases, ________ are available that identify carriers and help define the odds more accurately © 2011 Pearson Education, Inc.

78. Figure 14.18

79. Fetal Testing In __________________, the liquid that bathes the fetus is removed and tested In ________________________________, a sample of the placenta is removed and tested Other techniques, such as _______________ ________________, allow fetal health to be assessed visually in utero © 2011 Pearson Education, Inc.

80. Video: Ultrasound of Human Fetus I

81. Figure 14.19 (a) Amniocentesis (b) Chorionic villus sampling (CVS) Ultrasound monitor Amniotic fluid withdrawn Fetus Placenta UterusCervix Centrifugation Fluid Fetal cells Several hours Several weeks Biochemical and genetic tests Karyotyping Ultrasound monitor Fetus Placenta Chorionic villi Uterus Cervix Suction tube inserted through cervix Several hours Fetal cells Several hours 11223

82. Newborn Screening Some genetic disorders can be detected at birth by simple tests that are now routinely performed in most hospitals in the United States © 2011 Pearson Education, Inc.