Video Script

*show words “Harmony School of Science - Sugar Land High School: Project Based Learning,” then “Genetics: Probability and Pedigree: STEM SOS Level II Project, ” then “Mendelian Genetics: By Olivia and Catherine”*

Olivia: Hello, I am Olivia from Harmony School of Science-High.

Catherine: Hi, my name is Catherine, and I also attend HSS-High.

Olivia: For our PBL project, we flipped coins to determine the genetic makeup of a species of plant that could either turn out to have purple or non-purple stems.

*show us flipping coins and recording the data*

Catherine: Our project deals with Mendelian Genetics, or the principles and laws created by Gregor Mendel.

Olivia: This great scientist was the first to realize that offspring didn’t simply receive a blend or average of traits from their parents. He cross-pollinated many generations of pea plants by hand before coming up with the Law of Segregation and the Law of Independent Assortment.

Catherine: You can find a full explanation of these laws and a lot more definitions on our website, but the most important thing is that some traits are dominant over others. For example *show related pictures*, in our experiment, if a plant receives one allele from a homozygous purple parent and the other allele from a homozygous non-purple parent, then its stem will be purple because purple is dominant over non-purple.

Olivia: However, this offspring will be heterozygous purple because it still contains one of each allele. If it’s crossed with another heterozygous purple plant, we can use the Punnett Square to determine the color of the stems of this grandchildren generation.

*show us filling out the Punnett Square for these genotypes*

Catherine: As we can see, 25% of the offspring will be homozygous purple, 50% will be heterozygous purple, and the last 25% will have non-purple stems, even though both of their parents’ stems were purple.

Olivia: These are the results that we got from flipping the coins. *show data tables* Although the experimental results don’t match the theoretical results exactly, they’re pretty close.

Olivia: We also drew three pedigrees tracing real-life traits and disorders through several generations. This first one *show PTC non-tasters pedigree* shows how the gene for not being able to taste a compound called PTC is passed on. As you can see, this can be read much like a family tree. The squares represent males, and the circles are the females. By analyzing who receives this trait, we can conclude that it’s recessive and autosomal because the offspring of affected parents often don’t receive the trait, and both genders have an equally likely chance of inheriting it.

Catherine: *show hypercholesterolemia pedigree* This next pedigree is for another autosomal condition, but this time it’s dominant. A child of a parent with high cholesterol will most likely inherit that trait. *pause, show hemophilia pedigree* And finally, hemophilia is an X-linked recessive disorder. It’s found only on the X chromosome, which makes boys much more likely than girls to receive it.

*show words “ELA Component”*

Olivia: Since excessive knowledge about your genes can lead to trouble, I wrote a problem/solution essay describing the problems caused by genome mapping, which has become very popular recently. In order for test subjects to avoid the anxiety and depression caused by finding out that they will develop some genetic condition in the future, patients should properly inform themselves and consider all the risks before getting their genes tested. People could also raise awareness of the fact that many employers and insurance companies discriminate against certain individuals just because of their genetic makeup. *show related pictures*

Catherine: And I wrote a creative writing story about a typical teenager who discovers the connection between the genetics that she’s learning about in biology class and her life, namely why she partially resembles her siblings and parents. *show illustration of the story* You can read what we wrote on our website.

*show words “Social Studies Connection” and related picture*

Olivia: Our project also has a lot to do with the world around us. All humans share 99.9% of our DNA; as a matter of fact, two people of the same height and different races are typically more genetically alike than two people of the same race and different heights. However, that extra 0.1% is what causes racism and discrimination around the globe. *show related pictures*

Catherine: No matter what country you travel to, you will always find prejudice, but we chose to focus on Japan and South Africa *show pictures of racial problems in Japan and South Africa* in particular because of Japan’s ethnic homogeneity and South Africa’s former Apartheid. Again, you can find more details on our website.

Both: Thanks for watching a Harmony Public Schools video.

*show credits, thank you, and STEM SOS logo*