Download Teacher Materials

The Making of the Fittest:
The Birth and Death of Genes
HANDS-ON ACTIVITY
TEACHER MATERIALS
ICEFISH ADAPTATIONS
OVERVIEW
This hands-on activity serves as an extension to the Howard Hughes Medical Institute’s short film The Making of the Fittest:
The Birth and Death of Genes (http://www.hhmi.org/biointeractive/making-fittest-birth-and-death-genes). We designed it
to reinforce the concepts of adaptation and the birth of new genes. Students perform a wet lab using simple materials
that help them understand the “antifreeze” adaptation described in the film.
KEY CONCEPTS AND LEARNING OBJECTIVES
• Mutations can result in both the appearance of new genes and the loss of existing genes.
• Changes in the environment where a population lives can change which traits (and therefore genes) are favorable.
Students will be able to
• follow the steps involved in setting up a simple experiment;
• gather and analyzed data; and
• make scientific claims based on evidence.
CURRICULUM CONNECTIONS
Curriculum
NGSS (April 2013)
Common Core (2010)
AP Biology (2012–13)
IB Biology (2009)
Standards
MS-PS1-4, MS-LS1-3, MS-LS2-1, MS-LS2-4, MS-LS1-5, MS-LS3-1, MS-LS4-4, MS-ESS2-6,
HS-PS1-5, HS-LS1-1, HS-LS1-2, HS-LS2-6, HS-LS3-1, HS-LS3-2, HS-LS4-2, HS-LS4-4, HS-LS4-5,
HS-ESS2-2
PS1.A, LS1.A, LS2.A, LS2.C, LS3.A, LS3.B, LS4.B, LS4.C, ESS2.E
ELA-Literacy.RST.9-10.1, ELA-Literacy.RH.9-10.4, ELA-Literacy.RST.9-10.7,
ELA-Literacy RST.11-12.1, ELA-Literacy.RST.11-12.7, ELA-Literacy.RST.11-12.9
1.A.1, 1.A.2, 1.A.4, 2.D.2, 3.C.1, 4.C.1
4.1, 4.3, 6.2, 7.5, C.1
KEY TERMS
evolution, mutation, natural selection, trait, variation
TIME REQUIREMENTS
This activity was designed to be completed within one 50-minute class period.
SUGGESTED AUDIENCE
This activity is appropriate for middle school life science and high school biology (all levels including AP and IB).
PRIOR KNOWLEDGE
Students should know that traits may be inherited and that some traits provide organisms with a greater chance to
survive and reproduce. They should know that specific genes code for the production of specific proteins, and that
mutations in these genes can have positive, neutral, or negative effects on the fitness of an individual.
MATERIALS
Each pair of students needs the following:
•
•
•
•
cup of ice plus some extra (Crushed ice works best.)
two cooled, small test tubes, no larger than 100 by 12 millimeters (for the best results)
thermometer
8-ounce polystyrene cup
Icefish Adaptations
www.BioInteractive.org
Published July 2012
Revised October 2013
Page 1 of 3
The Making of the Fittest:
The Birth and Death of Genes
•
•
•
•
•
•
•
•
HANDS-ON ACTIVITY
TEACHER MATERIALS
stirring rod or plastic spoon
measuring spoon (1 teaspoon) or electronic balance
safety glasses (optional)
rock salt or coarse table salt
felt-tipped marking pen
paper towels
container of water
container of “antifreeze protein solution”—To make this solution, mix 60 parts water with 40 parts “antifreeze.”
Antifreeze can be either real automobile antifreeze or corn syrup. A batch of 150 milliliters of the antifreeze protein
solution should be enough for every group in multiple classes to have its own small container. Label this container
“antifreeze protein solution.”
TEACHING TIPS
GENERAL
• You may want to show the short film more than once so students can take notes. Encourage them to write down
questions they have.
• Be sure to reinforce the concept that populations evolve over time; individuals do not evolve in their lifetimes.
• Reinforce that new traits may be favorable, neutral, or negative. Further, as environments change, so might the
adaptive value of the traits.
ANTIFREEZE EXPERIMENT
• You may want to aliquot water, salt, and the antifreeze protein solution for each student group. Label these containers
“water,” “sodium chloride,” and “antifreeze protein solution,” respectively.
• Have students work in pairs.
• Students should read the introduction before setting up the experiment.
• Cool the test tubes by keeping them in a cooler with ice or in a beaker of ice before the experiment. This way the tubes
are cool at the start of the experiment. The ice in this step does not need to be crushed.
• Use crushed ice for the salt and ice mixture. If you do not have an ice crusher, place some ice cubes in a heavy-duty,
quart-sized plastic bag, and on a wooden surface or thick plastic cutting board, hit it with the side of the head of a
hammer or wooden mallet. A quart-sized bag of crushed ice is more than enough per class.
• Students can place both the water and antifreeze test tubes in the same cup of ice to cool. This ensures that all the
conditions are the same. If you prefer, students can use two separate cups—one for the water test tube and one for
the antifreeze test tube. You might have two groups use the same two cups. This saves on the amount of ice you will
need.
• You could use an alcohol thermometer that reads below 0°C, a computer probe, or other digital thermometer to
record the temperature.
• Be sure to have students measure the temperature of the ice and salt mixture first. This will cool the thermometer.
Since the volume of water in each test tube is so small, a room-temperature thermometer could warm the contents
and result in inaccurate readings.
ANSWER KEY
PROCEDURE STEP 3
Fill the polystyrene cup with crushed ice. Add 8 grams (approximately 1 teaspoon) of salt to the cup of ice and stir to mix the
contents. Measure the temperature of the ice and salt mixture in the cup. Record your measurements below.
The temperature in the ice and salt mixture should be at or near 0°C.
PROCEDURE STEP 6
With a clean thermometer, measure the temperature of the contents of each test tube. Be sure to rinse and dry the thermometer
between measurements. Record the temperatures below.
The temperatures in the two test tubes should be within a degree or two of each other. They should be well above
0°C.
Icefish Adaptations
www.BioInteractive.org
Page 2 of 3
The Making of the Fittest:
The Birth and Death of Genes
HANDS-ON ACTIVITY
TEACHER MATERIALS
PROCEDURE STEP 8
a. List other icefish adaptations mentioned in the film.
Students may list the following adaptations: big jaw with many teeth, no scales, no red blood cells, watery
blood, no hemoglobin, and antifreeze proteins.
b. Write down how scientists think the antifreeze gene evolved.
Scientists think that the antifreeze gene evolved when another gene was duplicated and then several
mutations occurred in the copy, including multiple repeats of a short segment of DNA. The copy mutated and
evolved a new function.
PROCEDURE STEP 9
a. Check the test tubes you set up before watching the film. Measure the temperature in each test tube. Be sure to rinse and
dry the thermometer between measurements. Record your measurements below.
The test tube with the antifreeze protein solution (A) should be colder than the one with water (W), even
though the fresh water is partially frozen.
b. Describe any differences you observe between the two test tubes.
There should be ice forming in the water test tube (W) and not in the antifreeze protein solution test tube (A).
c. Form a hypothesis to explain how ice crystals interfere with the flow of blood and damage tissues.
Sample answer: “Ice crystals will grow and block the flow of blood through vessels. Ice crystals will also
expand and rupture cells, destroying tissues.”
QUESTIONS
1. Antifreeze proteins are found in icefish blood. Explain how the antifreeze proteins help the icefish survive in the Antarctic
Ocean. They prevent the blood from freezing or they prevent ice crystals from forming in the bloodstream.
2. Predict what would happen if you placed a fish that lacked the antifreeze protein into subfreezing waters. Explain your
prediction.The fish may die because the blood would freeze or ice crystals would form and damage the blood
vessels.
3. Refer to your film viewing notes (Step 8a). Several of the adaptations described in the short film are similar to antifreeze
protein production because they have to do with icefish blood. Select one of these adaptations and explain how it has enabled
icefish to survive in icy water. Adaptations related to icefish blood include the following. It is watery; the blood is
easier to pump when it is not thick and loaded with cells. It lacks red blood cells; red blood cells would make the
blood thicker and more difficult to pump and circulate. It lacks hemoglobin; ocean water is saturated with oxygen
and icefish can diffuse ample oxygen across their scaleless skin, so hemoglobin is not needed.
4. Explain what the following means: “Natural selection, which is not random, determines which chance events (mutations) are
retained.” Sample answer: “Mutations are random events that can sometimes result in new traits or phenotypes.
Through natural selection, phenotypes that give individuals a disadvantage in their environment become less
common and may be eliminated, and phenotypes that give individuals an advantage become more common,
likely persisting for generations.”
AUTHOR
Mary Colvard, Cobleskill-Richmondville High School (retired), New York
FIELD TESTERS
Marjorie Davis, Mount Saint Joseph Academy; Kimberly Hayen, Heritage High School
Icefish Adaptations
www.BioInteractive.org
Page 3 of 3