Genetics

Class Traits Lab

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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.

TRAIT:

ALLELE:

some examples….

Trait	Alleles
attached ear lobes	Yes	or	No
hitchhiker’s thumb	Yes	or	No
widow’s peak (pull hair back)	Yes	or	No
can he roll his tongue?	Yes	or	No

 

Procedure: Use this data table to keep track of the traits listed above.

Trait	# yes	# no	Total people	% yes	% no

 

1. Each member of your group will choose one of the above traits. Everyone in your group must have a different trait to research.
2. There are _____ people in class today. Circulate around the room, surveying students and recording the numbers of each allele for your trait, until you’ve gotten a total of _____ responses, one from every person in class.
3. When you’re done asking everyone, check to see that you’ve filled in the first four columns of your data table. Return to your group and exchange data.
4. Calculate the percentages of each allele (yes or no) for each trait. Fill in these numbers on your data table. Follow this example:

5 can roll tongue = 5_ = 0.25 0.25x100 = 25%

20 total students today 20

Questions:

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.

Trait	Dominant or recessive?	Allele letter
attached ear lobes
unattached ear lobes
hitchhiker’s thumb
no hitchhiker’s thumb
widow’s peak
no widow’s peak
can roll tongue
can’t roll tongue

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?