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Chapter Introduction Lesson 1 Mendel and His Peas Lesson 2 Understanding Inheritance Lesson 3 DNA and Genetics Chapter Wrap-Up. Chapter Menu. How are traits passed from parents to offspring?. Chapter Introduction. What do you think?

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  1. Chapter Introduction Lesson 1 Mendel and His Peas Lesson 2 Understanding Inheritance Lesson 3DNA and Genetics Chapter Wrap-Up Chapter Menu

  2. How are traits passed from parents to offspring? Chapter Introduction

  3. What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements. Chapter Introduction

  4. 1. Like mixing paints, parents’ traits always blend in their offspring. 2. If you look more like your mother than you look like your father, then you received more traits from your mother. 3. All inherited traits follow Mendel’s patterns of inheritance. Do you agree or disagree? Chapter Introduction

  5. 4.Scientists have tools to predict the form of a trait an offspring might inherit. 5.Any condition present at birth is genetic. 6.A change in the sequence of an organism’s DNA always changes the organism’s traits. Do you agree or disagree? Chapter Introduction

  6. Mendel and His Peas • Why did Mendel perform cross-pollination experiments? • What did Mendel conclude about inherited traits? • How do dominant and recessive factors interact? Lesson 1 Reading Guide

  7. Mendel and His Peas • heredity • genetics • dominant trait • recessive trait Lesson 1 Reading Guide - Vocab

  8. Early Ideas About Heredity • Heredity is the passing of traits from parents to offspring. • Gregor Mendel is known as the father of genetics—the study of how traits are passed from parents to offspring. Lesson 1

  9. Mendel’s Experimental Methods • Mendel studied genetics by doing controlled breeding experiments with pea plants. • There are two types of pollination: • self-pollination • cross-pollination Lesson 1

  10. Self-Pollination Lesson 1

  11. Mendel’s Experimental Methods(cont.) • When a true-breeding plant self-pollinates, it always produces offspring with traits that match the parent. • Mendel cross-pollinated pea plants himself and recorded the traits that appeared. Lesson 1

  12. Cross-Pollination Lesson 1

  13. Mendel’s Experimental Methods(cont.) Why did Mendel perform cross-pollination experiments? Lesson 1

  14. Mendel’s Results • Once Mendel had enough true-breeding plants for a trait he wanted to test, he cross-pollinated selected plants. • Plants are called hybrids if they come from true-breeding parent plants with different forms of the same trait. Lesson 1

  15. First-Generation Crosses Lesson 1

  16. Mendel’s Results (cont.) hybrid Science Use the offspring of two animals or plants with different forms of the same trait Common Use having two types of components that perform the same function, such as a vehicle powered by both a gas engine and an electric motor Lesson 1

  17. Mendel’s Results (cont.) • Mendel also cross-pollinated hybrid plants. • He observed that offspring of hybrid crosses always showed traits in a 3:1 ratio. Lesson 1

  18. Second-Generation (Hybrid) Crosses Lesson 1

  19. Mendel’s Results (cont.) Mendel recorded traits of offspring from many hybrid crosses. Lesson 1

  20. Mendel’s Conclusions Mendel concluded that two factors, one from each sperm and one from each egg, control each inherited trait. What did Mendel conclude about inherited traits? Lesson 1

  21. Mendel’s Conclusions (cont.) • A dominant trait is a genetic factor that blocks another genetic factor. • A recessive trait is a genetic factor that is blocked by the presence of a dominant factor. Lesson 1

  22. Mendel’s Conclusions (cont.) How do dominant and recessive factors interact? Lesson 1

  23. Genetics is the study of how traits are passed from parents to offspring. • Mendel studied genetics by doing cross-breeding experiments with pea plants. Lesson 1

  24. Mendel’s experiments with pea plants showed that some traits are dominant and others are recessive. Lesson 1

  25. What method did Mendel use to select which plants pollinated other plants? A. true breeding B. self-pollination C. cross-pollination D. bees Lesson 1

  26. How many dominant factors does a purple-flowering pea plant have? A. 0 B. 1 C. 2 D. 1 or 2 Lesson 1

  27. What is the approximate ratio of dominant to recessive expression when both parents are hybrid? A. 1 : 1 B. 2 : 1 C. 3 : 1 D. 4 : 1 Lesson 1

  28. 1. Like mixing paints, parents’ traits always blend in their offspring. 2. If you look more like your mother than you look like your father, then you received more traits from your mother. Do you agree or disagree? Lesson 1

  29. Understanding Inheritance • What determines the expression of traits? • How can inheritance be modeled? • How do some patterns of inheritance differ from Mendel’s model? Lesson 2 Reading Guide

  30. Understanding Inheritance • gene • allele • phenotype • genotype • homozygous • heterozygous • Punnett square • incomplete dominance • codominance • polygenic inheritance Lesson 2 Reading Guide - Vocab

  31. What Controls Traits • Mendel concluded that two factors—one from each parent—control each trait. • Mendel’s “factors” are part of chromosomes which exist as pairs—one chromosome from each parent. • Each cell in an offspring organism contains chromosomes from both parents. Lesson 2

  32. What Controls Traits(cont.) • A gene is a section on a chromosome that has genetic information for one trait. • The different forms of a gene are called alleles. Each chromosome has one allele for every gene on it. • The two chromosomes in an offspring cell may have the same or different alleles. Lesson 2

  33. Lesson 2

  34. What Controls Traits(cont.) • Geneticists call how a trait appears, or is expressed, the trait’s phenotype. • The two alleles that control the phenotype of a trait are called the trait’sgenotype. Lesson 2

  35. What Controls Traits(cont.) phenotype from Greek phainein, means “to show” Lesson 2

  36. What Controls Traits(cont.) • When the two alleles of a gene are the same, the genotype is homozygous. • If the two alleles of a gene are different, the genotype is heterozygous. Lesson 2

  37. What Controls Traits(cont.) Scientists use uppercase and lowercase letters as symbols to represent the alleles in a genotype. How do alleles determine the expression of traits? Lesson 2

  38. Modeling Inheritance A Punnett square is a model used to predict possible genotypes and phenotypes of offspring. Lesson 2

  39. Modeling Inheritance (cont.) A pedigree shows phenotypes of genetically related family members. Lesson 2

  40. Modeling Inheritance (cont.) How can inheritance be modeled? Lesson 2

  41. Complex Patterns of Inheritance • Sometimes traits appear to be blends of alleles. • Alleles show incomplete dominance when the offspring’s phenotype is a blend of the parents’ phenotypes. • Codominance occurs when both alleles can be observed in a phenotype. Lesson 2

  42. Complex Patterns of Inheritance (cont.) Some traits, such as human ABO blood type, are determined by more than one allele. Lesson 2

  43. Complex Patterns of Inheritance (cont.) Polygenic inheritance occurs when multiple genes determine the phenotype of a trait. How does polygenic inheritance differ from Mendel’s model? Lesson 2

  44. Genes and the Environment • An organism’s environment can affect its phenotype. • Some examples of environmental factors that affect phenotype are soil type that a flower is growing in or time of year that a butterfly develops. Lesson 2

  45. The genes for traits are located on chromosomes. Lesson 2

  46. Geneticists use Punnett squares to predict the possible genotypes and phenotypes of offspring. • In polygenic inheritance, traits are determined by more than one gene and have many possible phenotypes. Lesson 2

  47. What is the name for different forms of a gene? A. alleles B. phenotypes C. genotypes D. chromosomes Lesson 2

  48. What is the genotype when two alleles of a gene are the same? A. heterozygous B. dominant C. homozygous D. recessive Lesson 2

  49. What occurs when both alleles can be observed in a phenotype? A. incomplete dominance B. homozygous C. polygenic D. codominance Lesson 2

  50. 3. All inherited traits follow Mendel’s patterns of inheritance. 4. Scientists have tools to predict the form of a trait an offspring might inherit. Do you agree or disagree? Lesson 2

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