Gregor Mendel Was a Priest in the 19Th Century Who Loved to Garden

Unit 4 - Genetics: The Science of Heredity

Mendel’s Work

Gregor Mendel was a priest in the 19th century who loved to garden.

While tending his garden he wondered why some plants had traits similar to their parents, and some plants had different traits then those of their parents.

______: Each different form of a characteristic that an organism can pass on to it’s offspring.

Mendel decided to study ______. His research would eventually earn him the nick name “the father of ______”.

______: the passing of physical characteristics from parent to offspring.

______: the scientific study of heredity.

Mendel started his experiments with ______plants.

______: an organism that is the offspring of many generations that have the same trait. (purebred short pea plants come from short parents and short grandparents, and short great grandparents)

Once Mendel had purebred plants, he crossbred plants with different traits with one another.

In Mendel’s experiments, he called plants in the first cross the parental generation or ______.

The offspring of the P genertation he called the ______.

The offspring of the F1 generation he called the______.

Mendel’s Results

In all of Mendel’s crosses only one form of the trait appeared in the F1 generation, however, in the F2 generation the lost form of the trait always reappeared in about______of the plants.

Dominant and Recessive Alleles

______: A section of the DNA that codes for a specific trait. (hair color gene)

______: the different forms of a particular gene. (brown or blonde)

An organisms traits are controlled by the alleles it inherits from it’s parents. Some alleles are dominant while other alleles are recessive.

A ______allele is one whose trait always shows up in the organism when the allele is present.(written as a ______ letter)

A ______allele is one whose trait is hidden when the dominant allele is present. (written as a______letter)

Inheriting Alleles

For every ______you have, your DNA is carrying 2 ______. One came from your ______and one came from your ______.

If both are the ______version, you show the ______trait.

If both are the ______version, you show the ______trait.

If one is the ______version and one is the ______version, you show the ______trait.

Genotypesand Phenotypes

An organism that has two identical alleles for a trait is said to be ______.

RR= homozygous ______

rr= homozygous ______

An organism that has two different alleles for a trait is said to be ______.

Rr = heterozygous

An organism’s______ is its physical appearance or visible traits.

(tall, blonde, round seeds, brown eyes)

An organism’s ______ is its genetic makeup or allele combinations.

(Tt, bb, RR, Bb)