Why do families share similar features like eye and hair color? Why aren’t they exact clones of each other? These questions and many more will be answered as well look into the fascinating world of genetics!
Genetics asks which features are passed on from generation to generation in living things. It also tries to explain how those features are passed on (or not passed on). Which features are stay and leave depend on the genes of the organism and the environment the organism lives in. Genes are the “inheritance factors “described in Mendel’s laws. The genes are passed on from generation to generation and instruct the cell how to make proteins. A genotype refers to the genetic make-up of a trait, while phenotype refers to the physical manifestation of the trait.
We’re going to create a family using genetics!
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• Paper or use this Genetics Table
• Two different coins
• Glue or Tape
Step one: Creating the Parent Generation
- First you’re going to create the genetic make-up of the parents. Here’s how:
- Take out the Genetics Data Table, and flip the first coin to create the genetic profile for the mother.
- Flip the coin and in the Mother’s Hair trait column, write D for dominant if the coin reads heads, and R for recessive if tails in the table.
- Flip the coin again. In the Mother’s Hair trait column right after the first trait, write D for dominant if the coin reads heads, and R for recessive if tails in the table.
- If you flipped heads the first time and tails the second, you’d write “DR” in the Mother’s Hair box.
- Continue this process for all of Mother’s traits. You should have two letters in each box for the entire column.
- Repeat steps 3-6 for Father. When you’ve completely filled out Mother’s and Father’s columns, you’ve completed the paternal genetic profile. Now you’re ready for the next part:
Step two: The Child
- Will the child be a boy or a girl? To determine this, flip the second coin. Heads for a boy, tails for a girl. After this is decided, circle boy or girl under “child 1” on the Genetics Data Table.
- Now the first coin will represent the gene from the mother and the second coin will represent the gene from the father.
- Start with the Hair trait: Flip both coins. If the first coin is tails, take the first trait from the mother. If the first coin is heads, take the second trait.
- For example, if the first coin is tails, and the mother’s code is DR, then write “D” in the child one column for hair.
- Do the same thing for the father’s traits with the second coin. For example, if the second coin is heads, and the father’s code is DR, then write “R” in the Hair Trait column of child 1.
- By the end of this step, child 1 should have one letter from the mother, and one letter for the father in child 1’s hair trait column.
- Use the same steps used to find the genetic code for the hair trait to find the code for the rest of the traits. By the end all the traits should have one letter from the mother’s genetic code and one letter from the father’s genetic code.
Step 3: What the Child Looks Like
For example, if the hair color is DD, DR, or RD then the hair color is dark. If the hair color code is RR, then the hair color is light. Draw the traits on your paper!
You can repeat this for as many children as you would like in your family.
Step 4: Make another family and compare!
Are all families alike? What if you try this process again for another family? Do you see any similarities or differences? Do similar features come from dominant genes? Do differences come from recessive genes? What other traits would you include? Write this in your science journal!
In fact, most similarities should come from the dominant genes because they are expressed more often. The recessive genes are expressed less often, so the create the differences.
What percent of the children expressed the dominant allele of each trait? Did you get Mendel’s results? Do the calculations and check it out!
- What is the difference between a genotype and a phenotype?
- What is a dominant trait?
- What is a recessive trait?
- Assume B=Black hair and b=blond hair. Make a Punnet square to cross Bb with bb. Tell what the possibilities are for offspring hair color.
- Why don’t traits simply average out in offspring. For example, why does a tall plant crossed with a short plant not yield a bunch of average-sized plants?
- In your activity, what percent of the children expressed the dominant allele of each trait? Did you get Mendel’s results? Do the calculations and check it out!