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Genetics

Genetics. In the mid-19th century, a man named GREGOR MENDEL began to experiment with pea plants. He observed that pea plants could be tall, short, green seeds, yellow seeds. Sometimes pea plants looked like their parents, other times, they did not. What did he do?.

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Genetics

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  1. Genetics

  2. In the mid-19th century, a man named GREGOR MENDEL began to experiment with pea plants. • He observed that pea plants could be tall, short, green seeds, yellow seeds. • Sometimes pea plants looked like their parents, other times, they did not.

  3. What did he do? • Mendel cross-pollinated pea plants of different colors by removing pollen from one plant and placing it onto the flower of another plant. • He observed and recorded the traits of the offspring.

  4. Step 1: He crossed purebred TALL plants with purebred SHORT plants. All of the resulting offspring(F1 generation) were TALL.

  5. Step 2: He crossed plants from the F1 generation with each other and found that the offspring of this cross (F2 generation) were both short and tall!

  6. Dominant vs. Recessive Alleles • Alleles are the different forms of a gene. example: tall (T) vs. short (t) Some alleles are dominant, meaning that the trait always shows up. Other alleles are recessive meaning that the trait is hidden while the dominant trait shows.

  7. In fruit flies, long wings are dominant over short wings. A scientist crossed a purebred long-winged male fruit fly with a purebred short-winged female. Predict the wing length of the F1 offspring. If the scientist crossed a hybrid male F1 fruit fly with a hybrid F1 female, what would their offspring probably be?

  8. In rabbits, the allele for black fur is dominant over the allele for white fur. What combination of the alleles must the white rabbit be?

  9. Vocabulary (1) • Heredity – the passing of physical traits from parent to offspring • Trait – a characteristic of an organism (ex: short or tall) • Fertilization – when egg and sperm join to form a zygote.

  10. Vocabulary (2) • Purebred – offspring of many generations have same traits (ex: short x short = purebred short) • Hybrid – offspring that has two different alleles for a trait

  11. Vocabulary (3) • Genotype – the combination of alleles an organism has (example: Tt , TT, or tt) • Phenotype – the trait that appears as a result of a genotype in an organism (example: Tall because the organism’s genotype is TT or Tt)

  12. Vocabulary (4) • Homozygous – identical alleles for a single trait. Example: tt or TT • Heterozygous – two different alleles for a trait, hybrids are said to be this. ex: Tt

  13. Punett Square Practice

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