Francisca Lozano, Blackstock Junior High School

Amy Murphy, Rio Del Valle Junior High School

Summer Science Institute – CLU

7th Grade Life Science

 

 

DNA Mutations and a Comparison of Normal Hemoglobin and Sickle Cell Hemoglobin

 

CALIFORNIA CONTENT STANDARDS:

Genetics

2. A typical cell of any organism contains genetic instructions that specify its traits. Those traits may be modified by environmental influences. As a basis for under-standing this concept:

c. Students know an inherited trait can be determined by one or more genes.

d. Students know plant and animal cells contain many thousands of different genes and typically have two copies of every gene. The two copies (or alleles) of the gene may or may not be identical, and one may be dominant in determining the phenotype while the other is recessive.

e. Students know DNA (deoxyribonucleic acid) is the genetic material of living organisms and is located in the chromosomes of each cell.

 

Investigation and Experimentation

 

7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:

 

a. Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data.

 

b. Use a variety of print and electronic resources (including the World Wide Web) to collect information and evidence as part of a research project.

 

c. Communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence.

 

d. Construct scale models, maps, and appropriately labeled diagrams to communicate scientific knowledge (e. g., motion of Earth's plates and cell structure).

 

PURPOSE:

·        Define mutation and give an example of it. 

·        Identify and analyze the three different types of mutation (deletion, substitution and insertion).

·        Determine that differences in the amino acid sequence of a protein will determine the structure and function of a protein. 

 

MATERIALS:

Computer, paper, pencils and highlighters for students

 

LESSON 1

 

DNA CHAIN LETTER

1.      In this activity students receive a DNA chain letter (www.successlink.org/great2/g1621a.html).  We have modified this activity from Scott McQuerry’s original lesson plan in order to complete it in a shorter amount of time.  To view Mr. McQuerry’s full lesson click on the following link.   http://www.successlink.org/great2/g1621.html  

2.      Students must be arranged in groups of 4 or 5.

3.      The teacher then passes out a copy of the original letter to one student in each group.  The student is then given 10 minutes to copy down the original letter word for word.  When time is up the next student must then copy down the “copied” letter given to him by his classmate.  This will continue until all members of the group have had a chance to copy the letter.

4.      The instructions within the letter's message informs the students that they are to replicate the copy they receive, character by character. Even if a word is misspelled within the text, the student is to copy the error within their reproductions. This procedure allows for the chain letter to be used as a model for DNA replication and the inheritance of mutations. When a student misspells a word, the subsequent students will perpetuate the error by copying it into their reproductions. Since each individual delivers two copies of the letter to different students, the error will spread exponentially throughout the rows of students.

The error within the message of the text is analogous to a mutation within the DNA code. After each student participates with this activity, and the documents are spread out for them to observe, the students can map the path of errors that have been created and the mutation's inheritance throughout successive "generations" of letters. Three different types of DNA mutations can be observed in this activity. Some mistakes are simple misspelled words (substitution mutations), or involve the addition of previously unwritten words (insertion mutations), or perhaps entail the removal of a word (deletion mutations.) Although the students may initially desire to "see who made the most mistakes," it remains an authentic tool for students to become engaged with an analogous model for DNA inheritance.

At times, students overlook the instructions and correct the errors in the text. This, too, can be used as an educational model. This time, it models the actions of DNA repair. Just as mutations are being created, the cell's repair enzymes are constantly working to fix any mutations that are discovered. Inadvertently, the students who have made these corrections have become a part of the chain letter model. (McQuerry, Scott. http://www.successlink.org/great2/g1621.html)            

 

LESSON 2

 

POWER POINT PRESENTATION “GENETIC MUTATIONS”

              Genetic Mutations.ppt

 

 

LESSON 3

 

COMPARATIVE OBSERVATIONS USING BIOLOGY WORKBENCH

 

  1. Open Biology Workbench (http://workbench.sdsc.edu/)
  2. Set up a free account
  3. Click on “Enter Biology Workbench”
  4. Scroll down a click on SESSION TOOLS
  5. Click Start New Session
  6. Click Run
  7. Name your session (Hemoglobin)
  8. Click START NEW SESSION
  9. Click PROTEIN TOOLS
  10. Select NDJINN
  11. Click RUN
  12. Top box type Human Hemoglobin Beta
  13. Hits per page – 10
  14. Scroll down and select SDSCNR
  15. Scroll up and select SEARCH
  16. Select SDCSNR 201677, SDSCNR 487311
  17. Scroll to bottom and select IMPORT SEQUENCES
  18. You will see your selections
  19. Click SELECT ALL and CLUSTALW. This will give you a new screen.
  20. Click RUN, then click SUBMIT
  21. This new screen will give you the amino acid sequence of normal hemoglobin and sickle cell hemoglobin.

 

       ANALYZE AND CONCLUDE

  1. Students should study the two amino acids sequences and be asked to point out any differences they notice.   
  2. Students should then copy down the two amino acid sequences and highlight and label the mutated amino acid. (Glutamic acid to Valine).
  3. Discuss with students that Valine is a hydrophobic molecule (afraid of water) and ask them to hypothesize how that may affect the structure and function of the protein.

 

 

LESSON 4

 

CHIME TUTORIAL ON HEMOGLOBIN STRUCTURE

This can be done as a whole class project with teacher leading or students may view the tutorial independently.

 

ASSESSMENT

 

Quiz Questions:

  1. List the three types of mutations. How do they differ?
  2. What type of mutation causes sickle cell anemia?
  3. Explain why the substitution of valine from glutamic acid caused the change in structure of the hemoglobin.
  4. What are possible causes of mutations?

Alternative Assessment:

            Have the students prepare an instructional manual for their DNA.  The manual should include instructions for copying their DNA and translating it into proteins.  It should also include information about protecting their DNA from mutations by avoiding mutagens and correcting any mutations that occur.

WEB SITES

Joint Center for Sickle Cell and Thalassemic Disorders
http://sickle.bwh.harvard.edu
A site that provides information on many different aspects of hemoglobin, sickle cell disease and current treatments.

"New Hope for People with Sickle Cell Anemia"
http://www.fda.gov/fdac/features/496_sick.html
Revised edition of article by same title by Eleanor Mayfield which originally appeared in the May 1996 FDA Consumer.

Sickle Cell Information Center
http://www.emory.edu/PEDS/SICKLE
Another good overall source with information for both the layperson and the clinician.

Sickle Cell Syndromes
http://www.mc.Vanderbilt.Edu/peds/pidl/hemeonc/sickle1.htm
A site with information on a more clinical level.

http://gslc.genetics.utah.edu/units/disorders/sloozeworm/mutationbg.cfm