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HEREDITY

HEREDITY. BIG IDEAS: Traits and Heredity Gregor Mendel Punnett Square Cross Pollination of Flowers. WHO WAS GREGOR MENDEL?. Mendel was a monk who taught science and performed many experiments. Mendel discovered the principles of heredity in the monastery garden.

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HEREDITY

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  1. HEREDITY BIG IDEAS: Traits and Heredity Gregor Mendel Punnett Square Cross Pollination of Flowers

  2. WHO WAS GREGOR MENDEL? • Mendel was a monk who taught science and performed many experiments. • Mendel discovered the principles of heredity in the monastery garden.

  3. Unraveling the mystery • Mendel worked with plants and knew that inheritance patterns were not always clear. • EXAMPLE: Sometimes a trait that appeared in one generation (parents) was not present in the next generation (offspring). • BUT in the generation AFTER that the trait appeared.

  4. Self-pollinating peas • Mendel chose pea plants. • Pea plants were able to self-pollinate. • A self-pollinating plant has both male and female reproductive structures

  5. SELF-POLLINATING PEAS • Eggs (in an ovule) and sperm (in pollen) from the same plant combine to make a new plant. • Mendel was able to grow true-breeding plants. • When true-breeding plants self-pollinates, all of its offspring will have the same traits. • EXAMPLE: A true-breeding plant with purple flowers will have offspring with purple flowers.

  6. Cross-pollinating Peas • Pea plants can also cross-pollinate. • Cross pollination: pollen from one plant fertilizes the ovule of a flower on a different plant. • Pollen can be carried by insects to a flower on a different plant. • Pollen can be carried by the wind from one flower to another.

  7. CHARACTERISTICS • CHARACTERISTIC: a feature that has different forms in a population. • EXAMPLE: Hair color, eye color, skin color. • TRAITS: The different forms of these characteristics. • Mendel used different traits to study heredity. • He chose purple flowers and white flowers.

  8. MIX AND MATCH • Mendel used true breeding plants. • He decided to find out what would happen if he bred, or crossed, two plants that had different traits. • TO BE SURE THAT THE PLANTS CROSS-POLLINATED, MENDEL REMOVED THE ANTHERS SO THE PLANTS COULD NOT SELF-POLLINATE! • Then, he used the pollen from another plant to fertilize the plant.

  9. MENDEL’S FIRST EXPERIMENT • Mendel crossed purple flowers with white flowers. • RESULTS: All the offspring were purple. • Dominant Trait: Purple Flower • Recessive Trait: White Flower

  10. MENDEL’S SECOND EXPERIMENTS • Mendel allowed the first-generation of plants to self-pollinate. • The recessive trait of the white flower reappeared in the second generation.

  11. Ratios in mendel’s experiments • The recessive trait did not show up as often as the dominant trait. • Mendel decided to figure out the ratio of dominant traits to recessive traits. • A ratio is a relationship between two different numbers that is often expressed as a fraction. • Look at page 60 and calculate the ratios for each of those plants that Mendel crossed pollinated.

  12. I CAN STATEMENTS… I can tell you that a recessive trait is… I can tell you that a dominant trait is… I can tell you what cross-pollination is… I can tell you what true-breeding is… I can tell you what a Punnett Square is… GREAT JOB MY JUNIOR GENETICISTS!!! So proud of you!

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