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Inheritance Patterns and Human Genetics Chapter 12 Table of Contents Section 1 Chromosomes and Inheritance Section 2 Human Genetics.

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Presentation on theme: "Inheritance Patterns and Human Genetics Chapter 12 Table of Contents Section 1 Chromosomes and Inheritance Section 2 Human Genetics."— Presentation transcript:

1 Inheritance Patterns and Human Genetics Chapter 12 Table of Contents Section 1 Chromosomes and Inheritance Section 2 Human Genetics

2 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

3 Chapter 12 Chromosomes Genes reside on chromosomes. –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. Section 1 Chromosomes and Inheritance

4 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. Section 1 Chromosomes and Inheritance

5 Chapter 12 Karyotypes: Male and Female Section 1 Chromosomes and Inheritance

6 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

7 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

8 1. Thomas Hunt Morgan 2. Worked with Fruit Fly (Drosophila) a. 3 sets of autosomes b. 1 set of sex-chromosomes

9 Cross a red-eyed female (X R X R ) and a white-eyed male (X r Y o ). What is the genotype and phenotype?

10 Cross a heterozygous red-eyed female (X R X r ) and a white-eyed male (X r Y o ), What is the genotype and phenotype ?

11 Chapter 12 Effects of Gene Location Human Sex-Linked Traits –Colorblindness (sex-linked recessive) –Hemophilia (sex-linked recessive) –Duchene muscular dystrophy (sex-linked recessive) –Fragile X syndrome (sex-linked recessive) Section 1 Chromosomes and Inheritance

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16 Chapter 12 Effects of Gene Location, continued Linked Genes –Pairs of genes that tend to be inherited together are called linked genes. Chromosome Mapping –The farther apart two genes are located on a chromosome, the more likely a cross-over will occur. –Researchers use recombinant percentages to construct chromosome maps showing relative gene positions. Section 1 Chromosomes and Inheritance

17 Chapter 12 Mutations Germ-cell mutations occur in gametes and can be passed on to offspring. Somatic-cell mutations occur in body cells and affect only the individual organism. Section 1 Chromosomes and Inheritance

18 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. Remember Trisomy like Down’s Syndrome Remember Monosomy like Turner’s Syndrome Due to NONDISJUNCTION Section 1 Chromosomes and Inheritance

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20 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. Remember Trisomy like Down’s Syndrome Remember Monosomy like Turner’s Syndrome Due to NONDISJUNCTION Section 1 Chromosomes and Inheritance

21 Chapter 12 Chromosomal Mutations Section 1 Chromosomes and Inheritance

22 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 Chapter 12 Gene Mutations Section 1 Chromosomes and Inheritance

24 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

25 Section 2 Human Genetics Chapter 12 Objectives Analyze pedigrees to determine how genetic traits and genetic disorders are inherited. Summarize the different patterns of inheritance seen in genetic traits and genetic disorders. Explain the inheritance of ABO blood groups. Compare sex-linked traits with sex-influenced traits. Explain how geneticists can detect and treat genetic disorders.

26 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.

27 Chapter 12 Section 2 Human Genetics Pedigree for Cystic Fibrosis

28 Chapter 12 Some Important Genetic Disorders Section 2 Human Genetics

29 Autosomal recessive disorders a. Tay Sachs b. PKU- Phenylketonuria c. Albinism d. cystic fibrosis

30 Sickle-Cell Anemia (Autosomal Recessive)

31 Huntington’s Disease (Autosomal Dominant)

32 Autosomal Dominant a. achondroplasia (dwarfism)achondroplasia b. 15 year girls15 year girls

33 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.

34 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.

35 BLOOD TYPES: both Codominance and Multiple Alleles Cross a man with blood type AB and a women with blood type O. What are the possible genotypes and phenotypes for the offspring?

36 BLOOD TYPES: both Codominance and Multiple Alleles Cross a man with blood type A and a women with blood typeB. What are the possible genotypes and phenotypes for the offspring?

37 Chapter 12 Click below to watch the Visual Concept. Visual Concept Comparing Single Allele, Multiple Allele, and Polygenic Traits Section 2 Human Genetics

38 Chapter 12 Click below to watch the Visual Concept. Visual Concept Comparing Complete, Incomplete, and Co-Dominance Section 2 Human Genetics

39 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.

40 Chapter 12 Click below to watch the Visual Concept. Visual Concept Comparing X-Linked and Sex-Influenced Traits Section 2 Human Genetics

41 Section 2 Human Genetics Chapter 12 Detecting Genetic Disease Genetic counseling informs screened individuals about problems that might affect their offspring.

42 Section 2 Human Genetics Chapter 12 Detecting Genetic Disease Genetic screening examines a person’s genetic makeup through blood test.

43 Section 2 Human Genetics Chapter 12 Detecting Genetic Disease Amniocentesis and chorionic villi sampling help physicians test a fetus for the presence of genetic disorders. Ultrasounds

44 Section 2 Human Genetics Chapter 12 Objectives Analyze pedigrees to determine how genetic traits and genetic disorders are inherited. Summarize the different patterns of inheritance seen in genetic traits and genetic disorders. Explain the inheritance of ABO blood groups. Compare sex-linked traits with sex-influenced traits. Explain how geneticists can detect and treat genetic disorders.


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