Ch14 & 15 Genetics

Ch14 & 15 Genetics - Genetics Chapter 14 15...

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Click to edit Master subtitle style 11/10/10 PowerPoint Lectures for Biology  8th edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions  Genetics Chapter 14 & 15
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11/10/10 Heredity The transmission of genetic information from parent to offspring Genetic information (DNA) determines traits “Traits” are seen when genes (segments of DNA) are “expressed” (proteins made by the direction of the nucleotide sequence of a gene) Different genes (and therefore different traits) are present on different chromosomes
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11/10/10 Concept 14.1: Mendel used the scientific  approach to identify two laws of inheritance Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments Advantages of pea plants for genetic study: There are many varieties with distinct heritable features, or characters (such as flower color); character variants (such as purple or white flowers) are called traits Mating of plants can be controlled Each pea plant has sperm-producing organs (stamens)
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11/10/10 Mendel’s Experiments Mendel chose to track only those characters that varied in an either-or manner He also used varieties that were true-breeding (plants that produce offspring of the same variety when they self-pollinate)
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11/10/10 Mendel’s Experiments In a typical experiment, Mendel mated two contrasting, true-breeding varieties, a process called hybridization The true-breeding parents are the P generation The hybrid offspring of the P generation are called the F1 generation When F1 individuals self-pollinate, the F2 generation is produced
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11/10/10 Mendel’s Experiments
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11/10/10 Mendel’s Experiments
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11/10/10 Mendel’s Experiments
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11/10/10 Mendel’s Experiments When Mendel crossed contrasting, true-breeding white and purple flowered pea plants, all of the F1 hybrids were purple When Mendel crossed the F1 hybrids, many of the F2 plants had purple flowers, but some had white Mendel discovered a ratio of about three to one, purple to white flowers, in the F2 generation
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11/10/10 Mendel’s Experiments Mendel reasoned that only the purple flower factor was affecting flower color in the F1 hybrids Mendel called the purple flower color a dominant trait and the white flower color a recessive trait Mendel observed the same pattern of inheritance in six other pea plant characters, each represented by two traits
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11/10/10
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11/10/10 Mendel’s Model Mendel developed a hypothesis to explain the 3:1 inheritance pattern he observed in F2 offspring Four related concepts make up this model These concepts can be related to what we now know about genes and chromosomes
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11/10/10 Mendel’s Model – First concept The first concept is that alternative versions of genes account for variations in inherited characters For example, the gene for flower color in pea plants
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Ch14 & 15 Genetics - Genetics Chapter 14 15...

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