Summer SAVY, Session 3 Day 2, Dabbling with DNA (Schott) (3rd – 4th)
Today, we started with a Four-Corners getting-to-know-you activity. We then reviewed what we learned yesterday and started our unit on genetics. We watched a short video on Gregor Mendel and his pea studies that elucidated the fundamentals of heredity. Terms we covered today include genetics, heredity, trait, gene, allele, dominance, recessive, genotype, and phenotype. We used Punnett squares to do crosses and discovered that one can predict the outcome of a cross using the Punnett square. We finished the morning with a discussion of family trees (pedigrees), and the students began sketching out their family tree.
After lunch, we worked more on the family trees and saw how it’s possible to track the inheritance of a trait using the tree. Their “homework” tonight is to show you the tree and possibly ask you about the presence/absence of a trait in your family. Some simple traits that we looked at are dark/light hair, dimples/no dimples, curly/straight hair, and freckles/no freckles with the dominant form for each trait listed first. While these traits are not necessarily single-gene with dominant and recessive alleles, it is instructive to think of them in this way. Below is a hypothetical tree for freckles with the filled-in symbols representing individuals with freckles.
Ask your child to explain the tree. What do the circles and squares represent? Why is it not possible for individuals 1 and 2 in generation III to have freckles? They may want to work on their tree and fill in the phenotype (form of the trait) for each individual.
We finished the day with the Crazy Traits activity where two identical but heterozygous parents have multiple children. (Each parent has the same form of the trait but has a dominant and recessive allele in their genotype). They saw how the eight children were similar, but none were identical. They had a lot of fun with this activity and will probably be excited to tell you about it.
We look forward to learning more together tomorrow!
