Gene Frequency and Natural Selectioin

Learning Target: I can predict how the frequency of a gene will change within a population as a result of natural selection.

Introduction: Have a picture of an angler fish, or other odd plant or animal displayed at the beginning of class. Solicit student answers to the question: "Why does this thing look the way it does?" Focus in on the idea of adaptations and natural selection. Then focus on the idea of what produces the adaptations, and how they become common in a population.

Activity:

Background Information: A gene is nothing more than a section of DNA that contains the information necessary for ribosomes to make a protein. This is accomplished through the processes of transcription and translation. Sometimes, the base pairs in DNA are rearranged from their natural sequence. These “misprints” are called MUTATIONS. There are several different types of mutations, including deletions, insertions, and substitutions. In any case, the resulting traits that the gene produces can become modified, or mutated.

Directions: Complete the following exercise to investigate how mutations can affect individuals and populations.

Scenario: You are a wild animal known as a Studentis scientistis. This small mammal species is known to gather and eat small chocolate candies as their main food source. The majority of the Studentis scientistis have two hands, each with two fingers. The classroom population of Studentis scientistis has been exposed to high levels of radiation from a nuclear waste spill that occurred along Highway 155. The radiation has caused frequent mutations among the local population. Three common mutations have been identified:
1. Bound hands
2. Five fingered hands
3. Red spotted hands
This exercise will attempt to determine how each of these mutations impacts the animal’s ability to eat (and thus survive).

Procedures:

1. You will draw a number from an envelope that will serve to determine which, if any mutation you have. Draw a number from the envelope. On the paper you draw there will be a number that represents the following phenotype:
1. Bound Hands
2. Two hands, five fingers each
3. Two hands, two fingers each, red spotted hands
4. Normal- Two Hands, two fingers each

Write your phenotype here:__________________________________

2. Use tape, or markers as needed to create your phenotype with your hands.
3. After everyone in the class has acquired the proper phenotype we will move on to the next part of the activity.


4. When instructed by the teacher, you will attempt to pick up as many candies as you can and place them in the cup. You will have 20 seconds to pick up and store as many as you can. Be careful, the red candies are poisonous. If you accidentally eat one of them, you will die.
5. After twenty seconds, you will count and record the number of candies you successfully collected in the space below.

Candies Collected and Stored:_________________
6. The class will share data, use class data to fill in the table below.
Data Table
Name Phenotype Candies Collected








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Average Number Collected For Bound Hands: ______

Two Hands Five Fingers:_______

Two hands Two fingers Red Spots:________

Normal- Two hands two fingers:________

ASSESS:

Questions:

1. Which of the traits do you think will become more common among the population over time? Why?



2. Which traits do you think will become less common among the population over time? Why?



3. How did the red-spots affect the ability to survive? Do you think this mutation will become more or less common among the population? Why?




4. Make a graphical representation of how you think the frequency of each of the four genes will change over time.