AIM:  What is the HARDY-WEINBERG LAW?
Students will be able to obtain background information on the LAW by clicking on these links:
Everything you want to know, this link includes definitions, about the LAW written by one of Georgetown's college students.  http://library.thinkquest.org/19926/text/library/article/09a.htm
This particular link helps you see how the LAW works, if you didn't fully understand the in-class lab:
http://georgetown.edu/departments/biology/class/hardy/

INSTRUCTIONAL OBJECTIVE:  Students will learn about De Vries and his theory of mutation.  The Hardy-Weinberg Theory Law and conditions under which the law holds true will  also be  investigated.

MOTIVATION:  The class will begin the day with a DO NOW:  The students will do an in-class lab.  Handout will be given.

DEVELOPMENT:

1.  The students will begin the class with a DO NOW.

2.  The students will be given HANDOUTS for an in-class lab.

3.  The students will form groups of 3 or 4.

4.  The students follow the lab's instructions and find out for themselves the principles of the HARDY-WEINBERG LAW.

5.  The students will calculate and record their data and come to a conclusion.

6.  The finished lab will be collected and graded.

The Hardy-Weinberg Law states: "Under certain conditions, the relative frequencies of alleles for a given trait in a population do not change."  For example, if the frequency of gene p was 90%, and the frequency of its allele q was 10%, ordinary random mating would always produce a new generation with the same ratio of 90% p and 10% q. (expressed as: p2 + 2pq + q2 = 1)

OBJECTIVES:  1.  Calculate the frequencies of the dominant and recessive alleles for an inherited trait.  2.  Compare the frequencies of two alleles with the frequencies of their phenotypes.

MATERIALS:  Calculator

PROCEDURE:  1.  Tongue rolling is controlled by a single gene.  Persons homozygous dominant or heterozygous can roll their tongue.  Homozygous recessive individuals CANNOT.  See if you can roll your tongue, as shown by your teacher.  Following her instructions, indicate your phenotype on the blackboard.

             2.  Fill in the table provided.  From the class data, calculate q2, the fraction of individuals who are homozygous recessive for the trait (those who cannot roll their tongue).  Express this as a decimal value.  For example, if 3 out of 30 people cannot roll their tongues, then (3/30), or 0.1 of the class are homozygous recessive.  Record this value under the q2 column.

            3.  Calculate q, the frequency of the recessive allele, by finding the square root of q2. Record your answer.

            4.  Determine the frequency of the dominant allele, p, by using the formula p = 1 - q.  Record your answer in the table.

            5.  Calculate and record in the table the frequencies of the homozygous dominant (p2) and heterozygous (2pq) genotypes.

ANALYSIS AND CONCLUSIONS

1.  WHAT ARE THE FREQUENCIES FOR THE ALLELES THAT AFFECT TONGUE ROLLING?

_________________________________________________________________
2.  Is q, the frequency of the recessive allele, larger or smaller than the frequency of people showing the recessive trait? Why?

_________________________________________________________________

_________________________________________________________________

3.  If you tested 10,000 people, do you think the genotype frequencies would be the same as those in your class? Explain.

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

4.  If all Hardy-Weinberg conditions were met, what would be the next generation's allele frequencies?

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________
 
 

INSTRUCTIONAL OBJECTIVE:  Describe the evidence for spontaneous generation.  Explain how Redi used controlled experiments to disprove the widely accepted hypothesis of the spontaneous generation of maggots.  Explain how Spallanzani's and then Pasteur's experiments finally disproved the hypothesis of the spontaneous generation of microorganisms.

MOTIVATION:  Can you believe you came from nowhere?
Using the scientific method prove or disprove the question posed.
 

DEVELOPMENT:

1.  The students will begin the class with a REVIEW.
Biology The Study of Life by Prentice Hall, 1991
Read Pages 585-588 and answer questions 1-4 on page 588
In addition to the reading assignment students may go to the following sites for information on this subject:
Overall perspective on scientists who have dealt with this question may be found here:
http://projects.edtech.sandi.net/kearny/labor/notes/spontgen.html
For the scientific method and how Francesco Redi used it to prove his theory click here:
http://d.umn.edu/~aroos/METHOD.htm
ANSWERS:
1. What is spontaneous generation?
hypothesis that living organisms arise from nonliving matter in a few days or weeks

2. What did van Leeuwenhoek discover?
microorganisms living in water

3. Why did Pasteur alter the shape of his flasks in his experiments with spontaneous generation?
to prevent microorganisms or their spores from reaching the broth

4. What assumption did Redi make in his first experiment that forced him to conduct his second experiment?
assumption the circulation of air was not a factor in spontaneous generation.

2.  Students will be given time to answer the above mentioned questions.  Their teacher will give students picked to answer 5 points if they answer correctly.

3.  The students will be given information about Redi not mentioned in their reading.

Common Error: Redi believed that some organisms such as the oak gall wasp, were produced by spontaneous generation.  When Pasteur experimented with microorganisms and nutrient broth in 1860, the theory was finally disproved.

Background: Redi used the scientific method.  He made definite hypotheses and used controlled experiments to test his educated guesses.   He tested one factor or variable at a time.

4.  The students will be given information about Pasteur also not mentioned.

Background: In describing his results before the French Academy, Pasteur proclaimed, "Never will the doctrine of spontaneous generation arise from this mortal blow."

5.  Students will be asked to kindly look at the pictures that appear on page 589 and asked to describe the difference between them.

ANSWER:  The first is the Primitive Earth.  It has solar rays penetrating to the Earth's surface.  There is lightning, ammonia, methane, hydrogen and water vapor in the atmosphere.  The skies are blackened due to volcanic activity.  The oceans are bubbling and red hot.  The mountains and land have NO vegetation.

      The second picture shows the Modern Earth.  It is totally the opposite of the Primitive Earth.

6.  Students will be told that what they described is called the HETEROTROPH HYPOTHESIS: origin of life hypothesis.

The term will be written on the blackboard for the students to copy.

7.  Students will be informed that there have been other hypothesis' over the years.  Miller's Experiment simulating the early conditions of the Earth which they will read in tonight's homework assignment and the Graham Cairns-Smith proposal that the first so-called organisms were inorganic crystals of clay and asked to look at page 592.

HOMEWORK:  Read pages 436-440 and answer questions on page 443 (12-15)