OVERVIEW:
Students will learn about probability, by tossing a coin, and about basic
Mendelian genetics by conducting simulated “genetic crosses” with
mice that differ in eye color. Puppets will be used to illustrate the transfer
of genes for eye color from parents to offspring, allowing students to visualize
the inheritance of a single trait (eye color) in their simulated mice.
TERMS
USED:
Process related—observation,
hypothesis, comparison, classification, prediction, inference, data, random
sampling, probability
Content related—cell,
chance, characteristic, chromosomes, DNA, gamete, gene, genetics, inheritance,
meiosis, mitosis, offspring, traits (dominant and recessive)
OUTLINE
OF ACTIVITY:
During the first few minutes we will briefly review some of the concepts from
the previous workshop. We will then introduce the topic for this workshop—Genetics
and Inheritance. We will use the genetics research conducted by SREL researcher
Travis Glenn to draw the students into this important (but potentially difficult)
topic. Travis does some state-of-the-art genetics research, which can admittedly
be very complex, but some of the organisms he studies (e.g., ALLIGATORS!)
are so fascinating to kids that it makes a good hook.
The slide presentation is content heavy, but the terms and concepts introduced are essential to the hands-on activity. The more that the students can be exposed to some of the terms before the workshop the better. If they come to the workshop with an understanding of organs>tissues>cells>nucleus>chromosomes>genes>DNA they will be better able to understand the material.
After the slides we will have a couple of demonstrations, first about probability (using coin-flipping) and then about “genetic crosses” (using the students to act out a hypothetical cross to produce a litter of mice). Students will then work in pairs (within their group of four) to do their own probability exercise and a mouse breeding “experiment.” The most difficult concept to get across to them seems to be the difference between what they would predict would happen when two mice with a given set of traits breed (the “expected results”) versus the actual results that they get when they sample. We will be stressing this point over and over.
The students will be introduced to a term that is probability foreign to most folks—the Punnet square. The name is not necessarily important, but it is a very useful tool for generating a prediction about what the results of a genetic gross will be.
After the experiment the students will discuss their results in the science seminar. If time permits we will survey the class for common human traits that illustrate dominant and recessive characters.
