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Introduction

Introduction. Heredity. Gregor Mendel The Man, The Legend… Father of Genetics. Gregor Mendel. Priest who worked in the monastery garden Observed traits , or characteristics, of pea plants. Some were short or tall, had green or yellow seeds, etc.

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Introduction

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  1. Introduction

  2. Heredity Gregor Mendel The Man, The Legend… Father of Genetics

  3. Gregor Mendel • Priest who worked in the monastery garden • Observed traits, or characteristics, of pea plants. Some were short or tall, had green or yellow seeds, etc. • He did experiments on these pea plants for over ten years. • http://player.discoveryeducation.com/index.cfm?guidAssetId=AC056D43-D1C5-4200-AB9B-E564C7C74009&blnFromSearch=1&productcode=US

  4. Pea Plants • Pea plants are easy to study because their traits come in two forms (unlike human hair color). • They also produce lots of offspring per generation, so he could get lots of data. • They usually self-pollinate, but Mendel cross-pollinated them to chose the parents of a generation.

  5. Purebred • He would cross two plants with opposite traits, ex. One tall and one short. He picked purebred plants, which always produce offspring with the same trait as the parent. • He called the parents the parental, or P, generation. The offspring were the first filial generation, or F1.

  6. Parents: 1 Tall & 1 Short • F1 generation was all tall • F2 generation was ¾ tall, ¼ short • He did this for six other traits: seed shape, seed color, seed coat color, pod shape, pod color, and flower position. The “lost” trait always reappeared in ¼ of the F2 generation! • http://player.discoveryeducation.com/index.cfm?guidAssetId=7570E857-9BAE-4732-920F-CF79EACA9201&blnFromSearch=1&productcode=DSC

  7. Inheritance • Traits must come in pairs, with one from each parent. Some can hide others. Ex. Tall pea plant trait hides short pea plant traits • Today, these traits are called genes. • The different forms of genes are alleles. Ex. Each F1 plant got one tall allele and one short allele.

  8. Dominant & Recessive Traits • Individual alleles control the inheritance of traits. • Some are dominant and always show up. Others are recessive and are masked by the dominant trait. • The tall allele was dominant over the short allele. • Only plants that got 2 short alleles ended up short.

  9. Hybrids • The F1 plants are hybrids b/c they have 2 different alleles for the trait • In the F2 generation, some got 2 short alleles and were short, some got 2 tall alleles and were tall, and some got 1 of each and were tall.

  10. Genetic Symbols • We use letters to represent alleles. The dominant allele is capitalized and the recessive is lower case. • So a plant with_______ would be written like this _______ • 2 Tall alleles, TT • 1 tall, 1 short: Tt • 2 short: tt

  11. Father of Genetics • He presented his work at the monastery, but others didn’t realize its significance. Since he wasn’t at a university, word of his work didn’t spread. He was forgotten for 34 years…. • In 1900 his work was rediscovered and its importance realized. Now he’s considered the Father of Genetics.

  12. Genetic Principles • Traits, or characteristics, are passed on from one generation of organisms to the next generation. • The traits of an organism are controlled by genes. • Organisms inherit genes in pair, one gene for each parent. • Some genes are dominant, whereas other genes are recessive. • Dominant genes hide recessive genes when both are inherited by an organism. • Some genes are neither dominant nor recessive. These genes show incomplete dominance.

  13. Vocabulary • Gregor Mendel: father of genetics; studied pea plants • Genetics: scientific study of heredity, or the passing on of traits from an organism to its offspring • Dominant trait: the stronger trait (dominates recessive traits- always appears) **represented by a capital letter Ex: “T” would represent the gene, tallness • Recessive trait: the weaker trait (usually hidden by the dominant trait- seems to disappear) **represented by a lowercase letter Ex: “t” would represent the gene, shortness • Genes: set of instructions for each characteristic • Alleles: two forms of a gene • Phenotype: inherited appearance (brown hair) • Genotype: inherited combination of alleles (letters)

  14. Vocabulary Notes • Gregor Mendel: ________________________________________________________________ 2. Genetics: ________________________________________________________________ 3. Dominant Trait: ___________________________________________________ Ex: _____________________________________________________________ • Recessive Trait: ___________________________________________________ Ex:______________________________________________________________ 5. Genes_____________________________________________________________________________________________________________________________ 6. Alleles: __________________________________________________________________________________________________________________________________ 7. Phenotype: __________________________________________________________________________________________________________________________________ 8. Genotype: __________________________________________________________________________________________________________________________________

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