Double Helix, by James Watson & Francis Crick
Class Traits Lab
Purpose: Survey your classmates to find out which versions of certain characteristics (or traits) are more common and which are less common.
Background: Let’s start by re-writing a couple of the definitions you just got from the lecture.
Procedure: Use this data table to keep track of the traits listed above.
5 can roll tongue = 5_ = 0.25 0.25x100 = 25%
20 total students today 20
1. Make a quick list – for each trait, write the allele that was more common
2. The more common allele of a trait is called the dominant allele. You can think of it as the stronger one. The allele that occurs less often is called the recessive allele (the weaker one). Fill in the middle column below, according to your data.
3. Scientists pick letters to represent traits, like abbreviations. The dominant allele is written with a capital letter; the recessive allele gets a lower case letter. Now fill in the third column above. Follow this example:
The example trait is hair color. I will be using the letter H. So….
Black hair is dominant, so I write it as an "H".
Blond hair is recessive, so I write it as an "h".
Now try it in the chart above using the traits you looked at in class today.
4. Hypothesize: Where does your body get these alleles from? Be more specific than just saying "my mom and dad".
5. Choose another trait to look at in your neighborhood. What are two allele types for this trait? Which is dominant and which is the recessive allele?