2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Inheritance Patterns & Human Genetics Developed By: R. LeBlanc Biology Teacher Mountain Pointe High School 11/’06

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Inheritance Patterns & Human Genetics Francis Collins and his lab group discovered the gene responsible for cystic fibrosis (CF). In this chapter, you will learn how diseases, such as CF, and characteristics, such as eye color, are inherited and expressed. Cystic fibrosis (CF) is the most common fatal genetic disease in the US today. It causes the body to produce a thick, sticky mucus that clogs the lungs, leading to infection, and blocks the pancreas, stopping digestive enzymes from reaching the intestines where they are required to digest food. CF is caused by a defective gene, which codes for a sodium and chloride (salt) transporter found on the surface of the epithelial cells that line the lungs and other organs. Several hundred mutations have been found in this gene, all of which result in defective transport of sodium and chloride by epithelial cells. The severity of the disease symptoms of CF is directly related to the characteristic effects of the particular mutation(s) that have been inherited by the sufferer. CF research has accelerated sharply since the discovery of CFTR in 1989. In 1990, scientists successfully cloned the normal gene and added it to CF cells in the laboratory, which corrected the defective sodium chloride transport mechanism. This technique - gene therapy - was then tried on a limited number of CF patients. However this treatment may not be as successful as originally hoped. Further research will be required before gene therapy, and other experimental treatments, prove useful in combating CF. Chapter 12

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cystic Fibrosis What do you notice about the airway of a normal person with one with cystic fibrosis?

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Chromosomes Genes reside on chromosomes. Section 1 Chromosomes and Inheritance How many chromosomes does a human cell have? 23 pairs or 46 How many chromosomes does a sex cell have? 23 What are genes? Genes are short segments of DNA that contains the instructions for a single trait.

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Karyotypes: Male and Female Section 1 Chromosomes and Inheritance

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Inheritance Patterns and Human Genetics Chapter 12 Table of Contents Section 1 Chromosomes and Inheritance Section 2 Human Genetics

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Objectives Distinguish between sex chromosomes and autosomes. Explain the role of sex chromosomes in sex determination. Describe how an X- or Y-linked gene affects the inheritance of traits. Explain the effect of crossing-over on the inheritance of genes in linkage groups. Distinguish between chromosome mutations and gene mutations. Section 1 Chromosomes and Inheritance

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Chromosomes, continued Sex Chromosomes and Autosomes –Sex chromosomes contain genes that determine an organism’s sex (gender). –The remaining chromosomes that are not directly involved in determining the sex of an individual are called autosomes. https://www.google.com/search?q=trisomy&rls=com.microsoft:e n-us:IE-SearchBox&oe=UTF-8&rlz=1I7SUNA_en&um=1&ie=UTF- 8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=YB4XT5eyEq HbiALth6jsDw&biw=1024&bih=563&sei=Yx4XT5C7AcqoiQKts6iq Dwhttps://www.google.com/search?q=trisomy&rls=com.microsoft:e n-us:IE-SearchBox&oe=UTF-8&rlz=1I7SUNA_en&um=1&ie=UTF- 8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=YB4XT5eyEq HbiALth6jsDw&biw=1024&bih=563&sei=Yx4XT5C7AcqoiQKts6iq Dw Section 1 Chromosomes and Inheritance What is wrong with the karyotyping above? What should it be? This causes birth defects and is known as Trisomy 13.

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Chromosomes, continued Sex Determination –In mammals, an individual carrying two X chromosomes is female. –An individual carrying an X and a Y chromosome is male. Section 1 Chromosomes and Inheritance

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sex Determination; con’t In humans there are 22 pairs of autosome (exact) chromosomes The 23rd pair are the sex chromosomes. Indicated by the letters X and Y. Ex. Female = XX Male = XY XX Y X XX Female XX Female XY Male XY Male Chapter 12

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Effects of Gene Location Sex-Linked Genes and Traits –Genes found on the X chromosome are X- linked genes. –A sex-linked trait is a trait whose allele is located on a sex chromosome. –Because males have only one X chromosome, a male who carries a recessive allele on the X chromosome will exhibit the sex-linked trait. Section 1 Chromosomes and Inheritance

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sex Linked Traits; con’t Examples: –Eye color in fruit flies –Hemophilia in humans - Unable to clot blood (recessive trait on the X chromosome) –Color Blindness in humans - Unable to see red and green –PROBLEM: If a man with hemophilia married and his wife was a carrier of hemophilia, what would the probability of their children of having this disease? Just the male child? Female child? Chapter 12

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Example of Sex-Linked Crosses XhXh Y XHXH XhXh X h Y = Male Hemophiliac XHXhXHXh Female Carrier XhXhXhXh Female Hemophiliac XHYXHY Male Normal XhYXhY Male Hemophiliac Chapter 12 H = Normal blood clotting h = hemophiliac

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sex Linked Traits; con’t People with red-green color blindness can not differentiate between these two colors Color blindness is also a X Linked Trait that is recessive. PROBLEM: A mother who carries the trait for color blindness wants to know what the probability would be that her children would be color blind if her husband has normal vision? R = Normal vision r = color blindness Chapter 12

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sex Linked Traits; con’t Chapter 12 XRXR XrXr Y XRXR X R X R X r X r YX R Y Female Carrier Color blindness solution 25% chance in all her children. 50% chance that a male will be color blind.. 0% chance female will be, but 50% chance they will be a carrier.

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Effects of Gene Location, continued Linked Genes –Pairs of genes that tend to be inherited together are called linked genes. –Why are these genes inherited together? They are inherited together because they are found on the same chromosome. Section 1 Chromosomes and Inheritance

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Effects of Gene Location, continued Chromosome Mapping –The farther apart two genes are located on a chromosome, the more likely a cross-over will occur. Example: If 2 genes are 2 times further apart than 2 other genes, what is the chances a cross-over will occur? TWICE AS LIKELY –Researchers use recombinant percentages to construct chromosome maps showing relative gene positions. Section 1 Chromosomes and Inheritance

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Mutations Germ-cell mutations occur in gametes and can be passed on to offspring. –Example: Colorblindness. Somatic-cell mutations occur in body that affect only the individual organism. –Example: skin cancer; cause by ?????? Section 1 Chromosomes and Inheritance

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Mutations, continued Chromosome Mutations –Chromosome mutations are changes in the structure of a chromosome or the loss or gain of an entire chromosome. Section 1 Chromosomes and Inheritance

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Chromosomal Mutations Section 1 Chromosomes and Inheritance

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Mutations, continued Gene Mutations –Gene mutations are changes in one or more of the nucleotides in a gene. Section 1 Chromosomes and Inheritance

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Gene Mutations Section 1 Chromosomes and Inheritance

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Inheritance of Traits Pedigrees –Geneticists use pedigrees to trace diseases or traits through families. –Pedigrees are diagrams that reveal inheritance patterns of genes.

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Pedigree for Cystic Fibrosis Section 2 Human Genetics

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Some Important Genetic Disorders Section 2 Human Genetics

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Genetic Traits and Disorders Polygenic Inheritance –Polygenic characters, such as skin color, are controlled by two or more genes. Melanin: a protein that determines how much skin color is going to be deposited in a skin cell. More melanin produced, more color is deposited. Other polygenic characteristics: eye color, height, and hair color.

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Genetic Traits and Disorders, continued Complex Characters –Many human conditions are complex characters, such as polygenic traits, are influenced by both genes and environment. –How can your skin color be influence by the environment? Height? –In diseases: breast cancer, diabetes, heart disease, stroke, etc. –Are there ways you can control disease factors to control your ability to contract a disease?

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Genetic Traits and Disorders, continued Multiple Alleles –Multiple-allele characters, such as ABO blood groups, are controlled by three or more alleles of a gene.

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Comparing Single Allele, Multiple Allele, and Polygenic Traits Section 2 Human Genetics

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Comparing Complete, Incomplete, and Co-Dominance Section 2 Human Genetics

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A cross where one allele does not completely hide or mask the other producing a blended appearance in the phenotype. Example: In snapdragons, pure red crossed with pure white produce pink! INCOMPLETEDOMINANCE

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu CODOMINANCE Two non-identical alleles of a pair specify two different phenotypes yet one cannot mask the other and both are expressed.

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Genetic Traits and Disorders, continued X-Linked Traits –The gene for colorblindness, an X-linked recessive gene, is found on the X chromosome.

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Genetic Traits and Disorders, continued Sex-influenced Trait –A sex-influenced trait, such as pattern baldness, is expressed differently in men than in women even if it is on an autosome and both sexes have the same genotype.

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Comparing X-Linked and Sex-Influenced Traits Section 2 Human Genetics

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Detecting Genetic Disease Genetic screening examines a person’s genetic makeup and potential risks of passing disorders to offspring. Amniocentesis and chorionic villi sampling help physicians test a fetus for the presence of genetic disorders.

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Detecting Genetic Disease, continued Genetic Counseling –Genetic counseling informs screened individuals about problems that might affect their offspring.

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Treating Genetic Disease Genetic disorders are treated in various ways. Among the treatments are symptom-relieving treatments and symptom-prevention measures, such as insulin injections for diabetes.

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 12 Genetic Disorder Section 2 Human Genetics

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Human Genetics Chapter 12 Treating Genetic Disease, continued Gene Therapy –In gene therapy, a defective gene is replaced with a copy of a healthy gene. –Somatic cell gene therapy alters only body cells. –Germ cell gene therapy attempts to alter eggs or sperm.

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice 1. Which can a chromosomal map show? A. the sex of the individual B. the presence of mutant alleles C. the positions of genes on a chromosome D. whether a gene is autosomal or recessive Standardized Test Prep Chapter 12

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 1. Which can a chromosomal map show? A. the sex of the individual B. the presence of mutant alleles C. the positions of genes on a chromosome D. whether a gene is autosomal or recessive Standardized Test Prep Chapter 12

44. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 2. Which can result from the deletion of a single nucleotide? F. trisomy G. a translocation H. nondisjunction J. a frameshift mutation Standardized Test Prep Chapter 12

45. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 2. Which can result from the deletion of a single nucleotide? F. trisomy G. a translocation H. nondisjunction J. a frameshift mutation Standardized Test Prep Chapter 12

46. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 3. At the present time amniocentesis cannot reveal which of the following? A. eye color B. genetic disease C. sex of the fetus D. chromosomal abnormalities Standardized Test Prep Chapter 12

47. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 3. At the present time amniocentesis cannot reveal which of the following? A. eye color B. genetic disease C. sex of the fetus D. chromosomal abnormalities Standardized Test Prep Chapter 12

48. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 4. A geneticist working with the fruit fly Drosophila melanogaster discovers a mutant phenotype that appears only in males who are offspring of males of the same phenotype. What does this information suggest about the mutant phenotype? F. The trait is X-linked. G. The trait is Y-linked. H. The trait is autosomal dominant. J. The trait is autosomal recessive. Standardized Test Prep Chapter 12

49. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 4. A geneticist working with the fruit fly Drosophila melanogaster discovers a mutant phenotype that appears only in males who are offspring of males of the same phenotype. What does this information suggest about the mutant phenotype? F. The trait is X-linked. G. The trait is Y-linked. H. The trait is autosomal dominant. J. The trait is autosomal recessive. Standardized Test Prep Chapter 12

50. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 5. Which statement best explains why men and women express the Bb genotype differently? A. The trait is polygenic. B. The trait has multiple alleles. C. Pattern baldness is a sex-linked trait. D. Pattern baldness is a sex-influenced trait. Chapter 12 The table below shows the genotypes and phenotypes of pattern baldness. Use the table to answer the question that follows. Standardized Test Prep

51. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 5. Which statement best explains why men and women express the Bb genotype differently? A. The trait is polygenic. B. The trait has multiple alleles. C. Pattern baldness is a sex-linked trait. D. Pattern baldness is a sex-influenced trait. Chapter 12 The table below shows the genotypes and phenotypes of pattern baldness. Use the table to answer the question that follows. Standardized Test Prep

52. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 6. translocation : chromosome mutation :: substitution F. gene mutation G. point mutation H. germ-cell mutation J. somatic-cell mutation Chapter 12 Standardized Test Prep

53. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 6. translocation : chromosome mutation :: substitution F. gene mutation G. point mutation H. germ-cell mutation J. somatic-cell mutation Chapter 12 Standardized Test Prep

54. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 7. Which type of inheritance pattern is associated with hemophilia? A. autosomal recessive B. sex-linked dominant C. sex-linked recessive D. autosomal dominant Chapter 12 The image below is a pedigree showing the inheritance of hemophilia in a family. Use the pedigree to answer the question that follows. Standardized Test Prep

55. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 7. Which type of inheritance pattern is associated with hemophilia? A. autosomal recessive B. sex-linked dominant C. sex-linked recessive D. autosomal dominant Chapter 12 The image below is a pedigree showing the inheritance of hemophilia in a family. Use the pedigree to answer the question that follows. Standardized Test Prep

56. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Short Response Consider a couple about to get married. The woman has cystic fibrosis, but the man does not. What benefit would they gain by seeing a genetic counselor? Chapter 12 Standardized Test Prep

57. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Short Response, continued Consider a couple about to get married. The woman has cystic fibrosis, but the man does not. What benefit would they gain by seeing a genetic counselor? Answer: Genetic counseling will tell them the likelihood of each of their children having cystic fibrosis or carrying the cystic fibrosis gene. Chapter 12 Standardized Test Prep

58. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Extended Response Colorblindness is a recessive, sex-linked trait. A woman and a man, both with normal vision, have three daughters with normal vision. One of the daughters marries a man with normal vision, and they have a son who is colorblind. Part A Which parent of the son is the carrier of the trait? Explain your answer. Part B What is the likelihood that the children of a woman heterozygous for colorblindness and colorblind man will express the trait? Explain your answer. Chapter 12 Standardized Test Prep

59. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Extended Response, continued Answer: Part A The son’s mother carries the trait. The gene for colorblindness is carried on the X chromosome. Part B Given: X-linked recessive: heterozygous female = X B (normal)X b (colorblind); colorblind male = X b (colorblind)Y. This Punnett square predicts that 50 percent of the children will be male and 50 percent of the children will be female. 50 percent will be colorblind and 50 percent will have normal vision. 25 percent will be males with normal vision and will not be carriers. 25 percent will be female carriers with normal vision. 25 percent will be colorblind females. 25 percent will be colorblind males. Chapter 12 Standardized Test Prep