Speed Dating with Gene Testing

Written by Kelly A. Hogan, University of North Carolina at Chapel Hill

Learning Outcomes:

– Evaluate the strength of the scientific studies presented at direct to consumer personal genomic testing services.

– Practice science communication through a two-minute discussion several times with different partners.

Activity Description: Students (for a class of approximately 30) are assigned prior to the activity one genetic test.  They will use the 23andme website to find out information about the gene test for their assigned trait/disease. During the activity, students follow a sort of “speed dating” protocol in which each student will meet with four other students (5 min each). After the four 5-minute sessions, students will be given an opportunity to choose other students’ presentations they found especially engaging.

Time Needed: 30 minutes in class

Materials Needed: Speed Dating with Gene Testing Homework and DNA Cards Worksheet

Activity Instructions: A week prior to the activity, assign each student to a genetic test (see the list and the student assignment attached). On the day of the activity, set up the classroom– make an inner circle and an outer circle of students, with equal numbers in each circle.  Randomly give five students one of the DNA cards before the activity begins. Each student is initially paired with and talks to another student for a total of 5 minutes. During this time, they each get about 2 minutes to tell each other what they learned.

While talking, each pair should have the list of “question prompts,” but they should not have their own notes out. They can each talk for two minutes straight or they can go back and forth for the 5 minutes. They can decide as a pair initially.

When the buzzer sounds, students in the outer circle rotate and meet with the next student for another 5 minutes. Repeat two more times, such that each student has spoken with four students over the course of 20 minutes. (Rather than a circle, you might try two rows of students in which one of the two rows moves every 5 minutes).

After the four 5-minute sessions, each of the five students with a card chooses one person they found especially engaging by giving them their DNA (a picture card, analogous to a reality show and a rose; see attached). Ask them to explain why. This is meant to get the discussion started, but others might want to also tell what they found most engaging.

Print an image like this to make the DNA cards:

 

 

 

 

 

 

Assessment:

Q: If an Asian male wanted to be tested by 23andme, would the results be applicable to him? Explain why or why not.

A: Yes and no. Many of the tests have been validated by studies of specific ethnicities but the studies have not been replicated in all populations. This does not mean that the results won’t hold true in other ethnicities, but there are limitations to the current knowledge. Nonetheless, many tests have been validated in multiple ethnicities. The site clearly states this for each gene test, so he can look to see which have been specifically validated in Asians.

Using a Food Analogy to Think About Protein Synthesis

Written by Kelly A. Hogan, University of North Carolina at Chapel Hill

Learning Outcomes:

– To think about transcription and translation broadly

– To think about the “instructions” a cell uses abstractly

Activity Description: Students work in pairs to think about how the “instructions” of the cell are used to make proteins and form an analogy using a restaurant. Students are asked to think about the molecular players of DNA synthesis and are asked to think about their counterparts in a restaurant. To promote discussion, students complete their answers on a blank paper or 3 x 5 index card. Once finished they will pass their answers randomly in the classroom and read each other’s ideas aloud. This activity can be done in a large class.

Time Needed: 15-20 minutes

Materials Needed: Paper or 3 x 5 index cards

Activity Instructions: On paper or index cards, have students think about the analogy that making proteins is like a meal that is made in a restaurant. Students begin by making a list of molecular players in transcripton, mRNA processing, and translation, and then consider who their counterpart would be in their analogy in a restaurant. You may choose to put a list of words they must use in their analogy (see boldfaced words below). There will be many variations. The value of this activity is in discussing why a particular analogy works or doesn’t work.

Example:

The restaurant’s large recipe book represents a DNA genome. A head chef writes out the recipe for the main course and posts it on a blackboard. The re-writing is transcription and the words written in chalk represent mRNA. (There may be hundreds of recipes, but the head chef only chooses one to make right now.) Some chefs modify the recipe by writing on the blackboard to add extra chili power or salt etc. (This represents mRNA processing.) Next, each chef begins assembling the dish by bringing all the correct ingredients to the pot on the stove. The pot represents the ribosome and the ingredients represent the amino acids. The chef represents the tRNA who carries the right ingredients to the pot. The ingredients are added in the order dictated by the directions written in chalk and this cooking is analogous to translation. The final cooked dish represents the protein. This special dish may be temporary because the head chef can erase the blackboard at any time. mRNAs are also temporary; when they are not present, the protein cannot be made.

A restaurant can choose to make various appetizers, main dishes, and desserts on different nights. All of these recipes are in the big recipe book. This analogy can help with a discussion about how different cells in the body have the same DNA but express different proteins to specialize.

Students Perform a Protein Synthesis Play

Written by Kelly A. Hogan and James Oh, University of North Carolina at Chapel Hill

Learning Outcomes:

– To see how a DNA template codes for a protein

– To practice determining what amino acid a tRNA carries based on its anticodon

– To see how a single DNA change affects the protein’s structure

Activity Description: Student volunteers will be used to demonstrate protein synthesis starting with a DNA template. The rest of the class will help by thinking through the play with prompted questions.

Time Needed: 30 minutes as a whole class demonstration or longer if beginning with student group discussion

Materials Needed:

– Large cardstock pieces of four different colors to write sequences on (one color for DNA, one color for mRNA, a third color for tRNA, and a fourth color for amino acids)

– String to hang cardstock signs around the necks of students

– A baseball cap for the 5’ cap of mRNA and a scarf or boa to represent the 3’ poly(A) tail

– Student handouts of the mRNA codon chart or a projection of the chart via PowerPoint

– Large binder clips to link amino acids together

Activity Instructions:

  1. Explain to the students that they will be putting on a play called “From DNA to Protein.” Choose students to perform through a random selection, such as calling out a row and seat number. The worksheet below gives the titles for 7 acts of this play. For each act, the class (maybe in partners) will come up with some of the details of that act. You may choose to have them think through the whole process first, but I prefer having them think through one act at a time and then performing that act. You can perform the entire play a second time to show them the process continuously. I have fun randomly choosing volunteers with an easy web application that randomizes my class roster: http://classtools.net/education-games-php/fruit_machine/
  2. Act 1: Transcription: Set aside an area of your room that you designate as the nucleus and another area that is the cytoplasm. Have students “wear” a DNA sequence. Have six students wear DNA triplet codes in row 1: TAC GGA CTC CTC TTC ACT, and  have six students next to the other students wearing the complementary sequence of the other DNA strand: ATG CCT GAG GAG AAG TGA. Engage the students by asking them to name the complementary codons before handing them their sequences.
  3. Bring another student up who will be RNA polymerase. As RNA polymerase walks over to the DNA, have the two rows of DNA move apart. Ask them what kind of bond is being disrupted when DNA is pulled apart (Hydrogen bonds). Choose row 1 to be the template strand. RNA polymerase will then have a pile of RNA codons that are complementary to hang around their necks (have a different colored cardstock form DNA) to make mRNA. Once again, have students participate to call out the codons. Discuss how uracil replaces thymine in mRNA. Students can link arms to show the covalent bonds formed between the RNA nucleotides.
  4. Act 2: mRNA Matures: The students wearing mRNA will now be processed. Call up other students to represent enzymes that perform the processing steps. Have a student add a 5` cap by having the first mRNA student stick their arm out. The enzyme can put a baseball cap on the arm. Have another student remove one of the two GAGs that will arbitrarily represent an intron. Have the remaining students splice their codons together. Lastly, have the last of the mRNA codon students hold a long scarf or boa to represent the poly(A) tail.
  5. The mRNA students should move as a group to the area of the room labeled cytoplasm. Stress that only after processing does the mRNA exit the nucleus. You may decide now is a good time to discuss the differences between prokaryotes and eukaryotes (with no nucleus and splicing, prokaryotes can begin translation as transcription is still finishing). You may also discuss the advantages of a nucleus and the stability of DNA vs. the short half-life of mRNA and how mRNA breakdown affects gene expression.
  6. Act 3: Translation Initiation: I like to use two chairs in the front of the room for the ribosome grooves in which tRNA students will temporarily sit. Translation is the most difficult aspect of protein synthesis because students often get confused about what the tRNA anticodon is complementary to. I have the chain of mRNA students stand behind the chairs with the first two codons aligned with the two chairs. I then have several students floating around the cytoplasm that are wearing tRNA anticodons around their neck. They are also holding amino acid names, but the audience cannot see which ones each tRNA is holding yet. It is useful to ask the students what the anticodon of the initiator tRNA should be that will recognize the first codon (UAC). The student wearing UAC will sit in the first chair. Ask them, “What amino acid will this tRNA be carrying?” (Met). This is often the first place students have trouble because they look for the anticodon sequence on the mRNA codon chart instead of the codon sequence. Ask them, “Which of our tRNAs should sit down in the second chair?” (The tRNA with GGA around its neck). Then ask them, “What amino acid is this second tRNA holding?” (Pro).
  7. Act 4: My Growing Polypeptide: Have the tRNA students in the chairs use binder clips to attach the first two amino acids together. The initiator tRNA can move out (point out that this tRNA can be recycled and can be charged with another Met). The tRNA codon now holding the first two amino acids will shift over as will the mRNA chain of students standing above. The next tRNA will sit down in the empty chair. Continue forming peptide bonds (with binder clips) and continue having students name the tRNA anticodon and amino acid that will enter. Repeat until the stop codon is reached.
  8. Act 5: When Will It End?: Students will reach the codon that they will recognize as a stop codon. Discuss how the ribosome, mRNA, and tRNAs are released. Stress that the mRNA still has some more time and has not been degraded yet as other ribosomes can attach to it. (In fact, multiple ribosomes can be attached to the same mRNA once the start codon emerges from the first ribosome.)
  9. Act 6: Just the Beginning for a Young Protein: Have one student hold the four amino acids that are clipped with binder clips and folded, and clip them in a new way. Discuss primary, secondary, and tertiary structure. Have the student with the protein then move to another area of the classroom and discuss the secretory route for a protein (through ER, Golgi, vesicles, and plasma membrane) or how some proteins will remain in the cell.
  10. Act 7: Am I Normal?: You can choose to re-act the play changing one of the codons in the DNA to illustrate a base substitution. Show students how one amino acid would be different and discuss implications of a mutation. Alternatively, you can have students use the sequence on their worksheet to see this easily (right side of sheet).

Worksheet: From DNA to Protein Worksheet

I’m Not Sure I Liked James Watson: Using a Video to Tell the Most Exciting Discovery in Biology

Written by Kelly A. Hogan, University of North Carolina at Chapel Hill

Learning Outcomes:

– To learn the structure of DNA and the names of famous scientists that contributed to its dicsovery

– To appreciate that scientific discovery and competition involves real people with real personalities

Activity Description: Students watch part of the PBS special, The Secret of Life. Students have questions to fill in while watching to keep them actively engaged. Students then write short comments about the characters in the race.

Time Needed: 1 hour and 15 minutes (approximately 55 minutes video time, plus time to write comments and discussion)

Materials Needed: Worksheet and possibly notecards

Activity Instructions: Play the Secret of Life Video Part 1. I was able to show it online via:

http://videosift.com/video/DNA-The-Secret-of-Life-part-1-of-5

After the video, ask students to write their thoughts about two of the characters. Students can write short essays to be graded, or in a large class, students can write some anonymous comments on a small notecard. If using a notecard, students can then swap them with classmates. Classmates then volunteer to read the comments on the card they are holding. Students have fun reflecting on the different personalities and it brings a personal aspect to science.

More to discover at the PBS website: http://www.pbs.org/wnet/dna/episode1/index.html

Worksheet: I’m Not Sure I Liked James Watson Worksheet

Interactive Celebrity Parents Genetic Inheritance Game

Written by Sheri L. Kuslak, University of North Carolina at Chapel Hill

Learning Outcomes:

– To practice using Punnett Squares to assess risks of inheriting a genetic disorder

– To illustrate the different use of the terminology when discussing genetic disorders including: genotype, carrier, homozygous, heterozygous, affected, unaffected, dominant, recessive

– To make genetic testing feel more personal to elicit discussion of some of the social and ethical impacts of genetic testing

Activity Description: Students will be assigned to a “family” in which several of their classmates become their siblings and their parents are one of four celebrity couples. They are given the genotypes of their parents for three fictitious genetic disorders: Spontaneous Death at 40 (SD40), Hot Pink Hair at 50 (HPH50), or Exercise Addiction (EA). As a group, the siblings must determine their risks of developing the genetic disorders and which disorders they would and would not be tested for. Students will then draw each Punnett Square on the board and discuss the pros and cons for testing for these traits.

Time Needed: Minimum of 40 minutes

Materials Needed: Worksheets including the table below and the Celebrity Parents for each group

Activity Instructions:

  1. Break students up into groups of up to 7 students, assign and distribute one celebrity couple to each group.
  2. Ask students to work together to determine the percent risk of them developing each of the genetic disorders based on their celebrity parents’ genotypes, and discuss whether as a family they should get tested. (Estimated Time: 10-20 minutes.)
  3. Start with the SD40 gene and have a representative from each family come to the board and draw their familyPunnett Squarefor this gene. Have the students report the percent of offspring that would be affected by the disorder. Repeat with the HPH50 and EA gene.
Possible discussion questions:
  1. Would you get tested for SD40 if you knew there was a chance you were genotype dd? Is the test useful if there is no treatment? How is this phenotype similar to Huntington’s disease? (Huntington’s is dominant, so it is inherited differently, but the phenotype is similar.)
  2. If you decided to get tested and your genotype was dd, would you date? Would you have children?
  3. Would you get tested for HPH50? Why or why not?
  4. If your parents are still under the age of 50 and were never tested for HPH50 disorder, and you discover that you carry the mutant allele, what does that mean to one of your parents? What if instead of pink hair, it was that you tested positive for the dominant allele for Huntington’s Disease? What if your parent didn’t want to know their status, but you tested positive?
  5. If you inherit two copies of the e allele, will you develop Exercise Addiction? What precautions might you take if any if you knew this was your genotype?
  6. What if instead of being addicted to exercise you had an increased risk of alcoholism. Would you get tested for this? Would this affect how you approach drinking?
  7. A mutation in a gene for breast cancer (BRCA-1 or BRCA-2) can increase a woman’s risk for developing breast cancer as much as 50-80%. If you were at an increased risk of developing cancer of a specific organ, would you want to get tested? Would you take any preventative action?

Student Demonstration of Mitosis and Meiosis Using Chromosome Cut-Outs as Models

Written by Kelly A. Hogan, University of North Carolina at Chapel Hill

Learning Outcomes:

– To compare mitosis and meiosis

– To demonstrate the meaning of the words: haploid, diploid, homologous chromosomes, and sister chromatids

– To demonstrate how independent orientation during meiosis leads to variation

Activity Description: Students will use cut-out chromosome models to demonstrate the stages of the cell cycle at their individual desks and/or by taping the cut-outs to a large board in the classroom as part of a whole class activity. Using big models as a large class activity can be used after smaller groups have tried this or can be used as a standalone activity, inviting a few students at a time to answer questions. Students will be asked to show specific phases of the cell cycle and to define words via demonstration by moving around the chromosome models.

Time Needed: 10-15 minutes as a whole class demonstration or up to 45 minutes in student groups with discussion

Materials Needed: Scissors, tape, and large chromosome cut-outs or individual worksheets students use to cut out chromosomes by themselves

Activity Instructions:

1. Have the students pick up two chromosomes that are homologous. Have them pick up two chromosomes that are sister chromatids. Ask them to explain the difference in definitions between sister chromatids and homologous chromosomes.

2. Ask the students, “Do you need all the pieces above for both mitosis and meiosis?” (Yes.)

3. Have students use the chromosomes to demonstrate the stages of mitosis by moving the chromosomes around on a whiteboard or on their desk. (Have them begin in G1, prior to DNA replication.) Use this time to ask them why 2n = 6.

4. Have the student demonstrate meiosis stages starting with G1 and stopping with metaphase I (You can choose to ignore crossing over at this point to simplify). Use this time to stop and ask how metaphase I is different from metaphase of mitosis (they should point out homologous chromosome pairing in metaphase).

5. Students should be able to demonstrate different independent orientations that can randomly occur at metaphase I. You might get them to figure out how many different alignments there are. (There are four possible alignments when n = 3.)

6. Have students complete meiosis I with one alignment of metaphase I, writing down the combinations of alleles they would wind up with in the gametes. Have them go back and choose another alignment to see that different gametes can form. Discuss Mendel’s Law of Independent Assortment and how this creates variation in gametes.

7. Have students define haploid and diploid using the chromosomes to demonstrate.

8. Ask them what their chromosomes might look like if there was crossing over with the AB homologous chromosomes (you may choose to cut and tape the chromosomes to demonstrate the recombination that occurs). Ask students when crossing over between homologous chromosomes occurs (prophase I) and be sure they understand that there is no crossing over in mitosis.

9. Ask the students various questions, such as:

“Can a gamete form that has alleles: A, B, H, R, d? Explain.” (Yes, crossing over between the AB genes, plus one of the HR chromosomes [no crossing over] and one of the d chromosomes.)

“Can a gamete form that has alleles: A, A, b, b, a, a, B, B? Explain.” (No, each gamete only gets one copy of each gene. Use an example like this to explain the term haploid again.)

10. Ask students to use the chromosome models to show you a cell in which 2n = 4 in G1.

11. Have students make a list of differences between mitosis and meiosis. Have them list similarities.

12. Ask students to reflect on the value of using models of chromosomes rather than looking at static images from the book or PowerPoint. Ask them to reflect on the value of this activity vs. watching an animation.


Applying the Concept of Non-Disjunction to Trisomy

Written by Kelly A. Hogan at University of North Carolina at Chapel Hill

Learning Outcomes:

– To understand how non-disjunction is abnormal meiosis

– To see how non-disjunction leads to trisomy

– To show students how to think through an application-based question

Activity Description: Students are given a question via PowerPoint as a clicker question and asked to do the problem alone. After collecting initial answers (and not telling them the correct one), students are then directed to work through the same problem using a helpful worksheet and neighbors. Students are then asked the same clicker question.

Time Needed: Approximately 15-20 minutes

Materials Needed: Worksheet or blank paper for students (if showing everything via PowerPoint)

Activity Instructions: You can insert this question into PowerPoint or use as a worksheet with the skeleton images. Consider using it as a clicker question if you are using clickers. This will likely be a tough one that students would benefit from a discussion with neighbors after trying it on their own and before being asked the same question again via clicker.

Question 1:

Do you really UNDERSTAND meiosis and non-disjunction? Try this question:

If an individual has the genotype XXY, did non-disjunction occur in their mother or their father (or both) and at which division(s), meiosis I or meiosis II?

A. Mother in meiosis I or II, Father in meiosis I or II

B. Mother in meiosis I or II, cannot be a non-disjunction in father

C. Cannot be a non-disjunction in mother, Father in meiosis I or II

D. Mother in meiosis I or II, Father only meiosis I

E. Mother only in meiosis I, Father only in meiosis I

*Choice D is correct. Students will have the most trouble with what happens after non-disjunction at Meiosis I. What they fail to understand is that the sister chromatids will still line up at meiosis II and separate. This is especially easy to spot with the father’s nondisjunction at Meiosis I. If they don’t understand this concept they will have a XX and a YY cell forming, instead of two XY cells.

Question 2:

If an individual has a genotype XYY, did non-disjunction occur in their mother or their father (or both) and at which division(s), meiosis I or meiosis II?

A. Mother in meiosis I or II, Father in meiosis I or II

B. Cannot be a non-disjunction in mother, Father in meiosis I or II

C. Mother in meiosis I or II, Father only meiosis I

D. Cannot be a non-disjunction in mother, Father in meiosis I only

E. Cannot be a non-disjunction in mother, Father in meiosis II only

*Choice E is correct. A sperm that was YY was fertilized with a normal egg.

Worksheet: Meiosis and Non-Disjunction Worksheet