INHERITANCE

Gregor Mendel was the first scientist to provide evidence and explanation for the inheritance of traits between parents and offspring. Cells are a central player involved in transmitting information from one generation to the next. When a sperm cell (male reproductive cell) unites with an egg cell (female reproductive cell) or when pollen (plant male reproductive cell) unites with eggs (plant female reproductive cells), the specific units of genetic information (DNA strands) for forming all of an organim's proteins and then traits--genes--in these cells contribute to the formation of a new organism--offspring. This new individual will have characteristics inherited from both parents.

For example, the following is a picture of a family composed of mom, dad, and two sisters. The mom comes from a family of seven--her mom, her dad, her three older brothers and one sister. The dad in this picture comes from a family of five--his mom, his dad, and his two brothers.

Take a moment to consider the following trait--tongue rolling! Some people are born with the genes that contribute to being able to roll the tongue, while others are born with genes that contribute to non-rolling. The mom and the dad in the above picture are both tongue rollers.The girls in the above picture are the offspring of this mom and dad. How is it then that one of the children is a non-roller and the other is a roller?
THE... ANSWER... IS... FOUND... IN... YOUR... UNDERSTANDING... OF... INHERITANCE!

This daughter has genes for non-rolling.

This daughter has genes for rolling.

Tongue rolling results from the presence of proteins in your tongue expressed by a gene pair. Each person, inherits one of the pairs of this tongue rolling gene from his / her mom and the other from his/ her dad. We will call the gene in the pair for tongue rolling "R" and the gene in the pair for non-rolling "r." So you could have the any combination for this tongue rolling gene from the following pairs:"RR" or "Rr" or "rR" or "rr. "
So why is one of these girls in this family a non-roller?

Look at the following chart:

Yes, you need more information about the mom and dad in the picture above. You also need to keep in mind that the only way for a person to be a non-roller is if he / she inherits a "r" from mom and a "r" from dad resulting in a "rr" gene combination. Using the data table below try to determine the gene combinations for each person in the mom's and dad's families--including the mom and dad in the picture. Click Here for the answers.

EXPLANATIONS
Her mom's gene combination "Rr" (She had a non-roller daughter and had to give a "r")
Her dad's gene combination "rr" (He is a non-roller and this is the only combination possible)
Her Brothers' gene combination "Rr" (They are rollers so they inherited the "R" from mom and
their dad could only contribute a "r")
Her Sister's gene combination "rr" (She is a non-roller and this is the only combination possible.)

The mom in the picture "Rr"(She is a roller so she inhertited an "R" from mom and her dad could only contribute a "r")

His mom's gene combination "rr"(She is a non-roller and this is the only combination possible)
His dad's gene combination "R?" (Need more information, because no kids express non-rolling. But since his is a roller you know that he has inherited at least one "R" from one of his parents.)
His brother's gene combination "Rr" (They are rollers so they inherited the "R" from dad and
their mom could only contribute a "r")

The dad in the picture "Rr" (He is a roller so he inhertited an "R" from his dad and his mom could only contribute a "r")

In conclusion, the mom in the picture could contribute either a "R" or a "r" to his daughters' and the dad in the picture could contribute either a "R" or a "r" to his daughters. As a result, the daughter who can roll her tongue could be "RR" or "rR" or "Rr" and the daughter who cannot roll her tongue must be..."rr"

GET IT NOW???!!!!!
If you are ready for more...click here for a detailed powerpoint which includes specific inheritance vocabulary, processes and prediction activities!