1. What does frequency mean
What does frequency mean? Create your own sentence using the word frequency.

2. Review: Definitions Gene- Allele- Homozygous- Heterozygous- Recessive-
Dominant-

3. Defintions
Gene- section of DNA that codes for a protein. Comes in two forms
Allele- One copy of a gene. Could be dominant or recessive
Homozygous- Two of the same alleles (TT or tt)
Heterozygous- Two different alleles (Tt)
Recessive- an allele that is masked by a dominant trait. You must have two copies to express the trait
Dominant-An allele that is always expressed even if you only have one copy.

4. Relative frequency of alleles: The number of times a particular allele occurs in a gene pool
In a population of 100 slugs, there are 50 yellow slugs (YY), 35 yellow-brown (YB), and 15 brown slugs (BB).

5. For Y, there are 50+50+35= 135 Y alleles.
Remember: in a population of 100 slugs, there are: 50 yellows (YY), 35 yellowish-browns (YB), and 15 browns (BB).
To figure out relative frequencies, we must see how many times the alleles for Y and B occur in our population.
There are 100 slugs. Each has two alleles for color. That means there are 200 alleles total.
For Y, there are = 135 Y alleles.
Divide 135/200=.675 x100 = 67.5%!
Do the same thing for B. You should get…

6. = 65 B alleles 65/200=.325 x 100 = 32.5%!
So, we have a relative frequency of 67.5% for the Y allele and 32.5% for the B allele.
Let’s say that a species of frog started to eat these slugs. The yellow ones were much easier for the frogs to see! What might happen?
If the relative frequencies change, EVOLUTION has occurred!

7. Exit Ticket
If 10 people in a population have blonde hair and all ten of those people are homozygous, what is the allele frequency of the blonde allele if the population has a total of 100 people?