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

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Inheritance Patterns and Human Genetics Chapter 12 Table of Contents Section 1 Chromosomes and Inheritance Section 2 Human Genetics Slide 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 Slide 3 Chapter 12 Chromosomes Genes reside on chromosomes. Section 1 Chromosomes and Inheritance Slide 4 Chapter 12 Chromosomes, continued Sex Chromosomes and Autosomes Sex chromosomes contain genes that determine an organisms 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 Slide 5 Chapter 12 Karyotypes: Male and Female Section 1 Chromosomes and Inheritance Slide 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 Slide 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 Slide 8 Chapter 12 Effects of Gene Location, continued Linked Genes Pairs of genes that tend to be inherited together are called linked genes. Section 1 Chromosomes and Inheritance Slide 9 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. Researchers use recombinant percentages to construct chromosome maps showing relative gene positions. Section 1 Chromosomes and Inheritance Slide 10 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 Slide 11 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 Slide 12 Chapter 12 Chromosomal Mutations Section 1 Chromosomes and Inheritance Slide 13 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 Slide 14 Chapter 12 Gene Mutations Section 1 Chromosomes and Inheritance Slide 15 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. Slide 16 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. Slide 17 Chapter 12 Section 2 Human Genetics Pedigree for Cystic Fibrosis Slide 18 Chapter 12 Some Important Genetic Disorders Section 2 Human Genetics Slide 19 Chapter 12 Genetic Traits and Disorders Polygenic Inheritance Polygenic characters, such as skin color, are controlled by two or more genes. Slide 20 Section 2 Human Genetics Chapter 12 Genetic Traits and Disorders, continued Complex Characters Complex characters, such as polygenic traits, are influenced by both genes and environment. Slide 21 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. Slide 22 Chapter 12 Click below to watch the Visual Concept. Comparing Single Allele, Multiple Allele, and Polygenic Traits Section 2 Human Genetics Slide 23 Chapter 12 Click below to watch the Visual Concept. Comparing Complete, Incomplete, and Co-Dominance Section 2 Human Genetics Slide 24 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. Slide 25 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. Slide 26 Section 2 Human Genetics Chapter 12 Detecting Genetic Disease Genetic screening examines a persons 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. Slide 27 Section 2 Human Genetics Chapter 12 Detecting Genetic Disease, continued Genetic Counseling Genetic counseling informs screened individuals about problems that might affect their offspring. Slide 28 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. Slide 29 Chapter 12 Click below to watch the Visual Concept. Genetic Disorder Section 2 Human Genetics Slide 30 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.

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