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Why do you look a little like mom and dad,but not exactly like either parent?

Heredity is the passing of traits from one generation to another.

Examples of traits include your eye color, the color of a cat, or the feathers of a bird.
In the 1800's Gregor Mendel, while growing pea plants, noticed that some traits like height of a plant may change from one generation to the next.
He found that when he bred two tall plants together, in the first generation he would get tall plants, but in the second generation he may get three tall and one short plant.

He classified the first generation trait as the dominant trait.
The trait that was masked of covered up as the recessive trait.

The reason you get dominant and recessive traits is that you get one copy of the trait from mom and another copy from your dad.

Most human cells are diploid because they contain a pair of chromosomes.
This helps explain why you look similar to your mom and dad, but not exactly.

The work of Gregor Mendel 11-1

Heredity
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Middle School Math and Science

Gregor Mendel and his accomplishments

Gregor Mendel is considered the father of genetics.
In the 1850’s Gregor Mendel was a monk fascinated with pea plants.
Almost by accident, he discovered the field of genetics.

He choose pea plants for his study of Genetics because
• They reproduce at a high rate which enabled Mendel to grow many plants
• They have several traits like seed shape that are easy to observe
• They are easy to cross-pollinate which allowed Mendel to determine which traits came from which parents.

In order to produce new plants, he had to fertilize the plants. Fertilization is the process of the egg and sperm joining to produce offspring.
A trait is a characteristic, like the color of the flower, that can be passed from one generation to another.

A trait is controlled by a section of DNA called a gene.
Traits have more than one form.
These different forms of the same trait are called alleles.

Mendel was careful to avoid self-pollination by removing the anthers of the flowers and carefully fertilized the plants himself.
An egg or a sperm only has half the genetic information of an organism.

The law of segregation states that only one allele will be present in the sperm or egg. When the egg and sperm are created the pairs of alleles of the parents separate, or as Mendel said,”segregate” from each other.
This helps explain why the offspring may have a different trait than the parent.

Important Genetic Vocabulary

Gene: A portion of DNA that contains the genetic code of a trait
Traits: A characteristic controlled by a gene
Allele Different forms of the same trait
Gametes A sperm or egg. Each contains half the genetic information of an organism.