AEarly Ideas about Heredity
- Heredity is the passing of traits from parents to offspring.
- In the 1850s, Gregor Mendel, an Austrian monk, performed experiments that
helped answer questions about how traits are inherited.
- Genetics is the study of how traits pass from parents to offspring.
BMendel’s Experimental Methods
- Pea plants were ideal for genetic studies because they reproduce quickly; they have
easily observed traits; and the experimenter can control which pairs of plants
reproduce.
- Mendel controlled which plants pollinated other plants.
AWhen a(n) true-breeding plant self-pollinates, it always produces offspring with
traits that match the parent.
BBy cross-pollinating plants himself, Mendel was able to select which plants
pollinated other plants.
- With each cross-pollination Mendel did, he recorded the traits that appeared
in the offspring.
- Mendel’s crosses between true-breeding plants with purple flowers produced plants
with only purple flowers. Crosses between true-breeding plants with white flowers
produced plants with only white flowers.
- Crosses between true-breeding plants with purple flowers and true-breeding plants
with white flowers produced plants with only purple flowers.
- The first–generation purple-flowering plants are called hybrid plants.
- When Mendel cross-pollinated two hybrid plants, the trait that had disappeared
in the first generation always reappeared in the second generation.
- Mendel analyzed the data from many experiments on seven different traits. He
always noted a 3:1 ratio; for example, purple flowers grew from hybrid crosses three
times more often than white flowers.
- After analyzing the results of his experiments, Mendel concluded that two factors
control each trait.
- Mendel also proposed that, when organisms reproduce, each reproductive
cell—sperm or egg—contributes one factor for each trait.
- A genetic factor that blocks another genetic factor is dominant.
These are not my words but I hope that they help you a lot .
