Download Clicker questions used in the activity, distribution of student answers

A clicker-based case study that untangles student thinking about the processes in the central dogma
– Supporting File 2.
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Supporting File 2. Clicker questions used in the activity, distribution of student answers, and
explanations for the range of student answers.
Clicker questions are presented below with the correct answers after peer discussion
indicated in blue text. The weighted average (WA) of student responses from 8 different
classes is indicated in parentheses. Percentages that do not equate to 100 are due to
missing responses. Each question is followed by a brief explanation of the observed clicker
responses.
Q1: Is difference #5 a possible cause of DMD in Liam?*
A. Yes (85%)
B. No (14%)
Difference #5 represents a missense mutation: in Elijah (unaffected) the DNA encodes for
GAU (aspartate) and in Liam (affected) the DNA encodes for GAG (glutamate). This
question is an exploratory question, and most students answer A: “Yes” because, without
more information, this difference is a possible cause of the disease. In the next slide,
students will learn that aspartate and glutamate are similar in structure.
Q2: If difference #1 caused DMD, we would predict the mRNA levels in Liam to be
__________ the mRNA levels in Elijah?
A. the same as (8%)
B. higher than (12%)
C. lower than (65%)
D. different in some way from (15%)
This question is asking students to examine the promoter region of the gene and to predict
how this type of mutation would affect the mRNA levels. The correct answer is D, but often
students arrive at C, thinking that a mutation will always reduce transcription. This
question can be used to discuss effects of mutations in promoter regions in general, and
that a mutation does not always have to down regulate a promoter.
Q3: You have now done the experiment and measured the mRNA levels in both Elijah
and Liam. If these are your results, would you conclude that difference #1 a likely
cause of DMD in Liam? *
A. Yes (9%)
B. No (90%)
The students observe that there is no change in the amount of mRNA as a result of the
promoter mutation and can therefore conclude this difference is likely not a cause of DMD
in Liam. The majority of students answer correctly (B).
* Percentages that do not equate to 100 are due to students omitting responses to a particular
question or selecting an answer that is not part of a given question.
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A clicker-based case study that untangles student thinking about the processes in the central dogma
– Supporting File 2.
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Q4: When DNA polymerase reaches the nucleotides encoding the premature stop
codon it will…*
A. stop when it reaches the first nucleotide encoding the premature stop codon. (31%)
B. stop when it reaches the last nucleotide encoding the premature stop codon. (42%)
C. not be affected by this base change and will continue to read through the nucleotide
difference. (26%)
This question is the first of several that address the effect of a premature stop codon on the
processes in the central dogma. The majority of students will incorrectly answer that the
DNA polymerase will stop prematurely (either A or B). The next slide promotes discussion
of the consequences of having DNA polymerase that stopped at every stop codon in the
genome.
Q5: When DNA polymerase reaches the nucleotides encoding the premature stop
codon it will…*
A. stop when it reaches the first nucleotide encoding the premature stop codon. (8%)
B. stop when it reaches the last nucleotide encoding or the premature stop codon.
(16%)
C. not be affected by this base change and will continue to read through the nucleotide
difference. (75%)
After the previous discussion, students vote again on the effect of a stop codon on DNA
polymerase. There is typically a shift towards the correct answer (C).
Q6: What do you predict will be the effect of the premature stop codon on mRNA
size? It will result in:
A. a shorter mRNA in Liam. (49%)
B. a longer mRNA in Liam. (5%)
C. the same size mRNA in both Liam and Elijah. (46%)
This question asks the students to predict the outcome of a premature stop codon on
mRNA size. Roughly half the students incorrectly choose (A), thinking that a premature
stop codon will stop transcription and result in a shorter mRNA.
* Percentages that do not equate to 100 are due to students omitting responses to a particular
question or selecting an answer that is not part of a given question.
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A clicker-based case study that untangles student thinking about the processes in the central dogma
– Supporting File 2.
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Q7: The above DNA sequence is being transcribed by an RNA polymerase (red
square). The premature stop codon mutation in Liam’s DNA is indicated in blue.
What will the RNA polymerase do when it reaches the nucleotides encoding the
premature stop codon? It will: *
A. stop when it reaches the first nucleotide encoding the premature stop codon. (9%)
B. stop when it reaches the last nucleotide encoding the premature stop codon. (24%)
C. not be affected by this base change and will continue to read through nucleotide
difference. (66%)
This question asks about the effect of a premature stop codon on RNA polymerase. The
format used is intentionally similar to that used asking about DNA polymerase (Q4 and 5).
Although how DNA polymerases function has already been addressed, many students still
answer this question incorrectly and vote that RNA polymerase will stop prematurely
(either A or B).
Q8: What do you predict will be the effect of the premature stop codon on protein
size? It will: *
A. result in a smaller dystrophin protein in Liam. (83%)
B. result in a larger dystrophin protein in Liam. (5%)
C. result in the same size protein in both Liam and Elijah. (11%)
This question addresses the impact of a premature stop codon on translation. By this point
in the lesson most students have recognized a stop codon will result in a shorter protein
and the majority of the students arrive at the correct answer.
Q9: Which of the five nucleotide differences are mutations? *
A. All five are mutations. (58%)
B. The three in the exons (difference #2, #3, #5) (16%)
C. The two in exons that change the amino acid sequence (differences #3, #5) (20%)
D. The one in the exon that causes DMD (difference #5) (5%)
The final clicker question addresses the students’ conceptual difficulty that nucleotide
differences are only mutations if they are in a coding region or impact phenotype. While
many students correctly answer that all of these nucleotide changes are mutations, a subset
still think that mutations are restricted to coding regions (answer B) or must change the
amino acid sequence (answer C). This question allows for a discussion on what defines a
mutation.
* Percentages that do not equate to 100 are due to students omitting responses to a particular
question or selecting an answer that is not part of a given question.
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