I know this is vague, and you wouldn’t understand unless you were in class, but
ID: 281093 • Letter: I
Question
I know this is vague, and you wouldn’t understand unless you were in class, but you could at least answer how the question could be worded differently to make it less “tricky"
Therefore, your answer should include a re-worded question (part A) and also the annotated key (preferably with diagram and words) - because I do not much understand the process myself.
Thanks in advance, of course I rate quick, and will get you multiple ratings from students in class!
The extra credit opportunity is based on the following question that appeared on Quiz 5 (both the Individual and Group parts). You are eligible for up to 5 points of extra credit for completing the following 3 questions (to be added to your final exam score). Your response to these questions is due at the start of class on Monday. Rewrite the question and present it in a way that you think clarifies what the question is asking. In other words, now that you know how to solve this question, how could the question itself be improved to prompt the correct answer choice? Or. what would have made it easier for you to understand what the question is asking? (In any case, to get credit for this part, you need to rewrite the question). A. Write an annotated key for the question. This can include diagrams and text (not just diagrams alone). Write the answer in a way that would be helpful for future Bio201L students to understand how to solve this question. B. C. Think about your thinking-This is a meta-cognition task. Reflect upon the discussion you had in class with your fellow students during the group quiz or, reflect upon your thinking while you completed parts A and B (above). Was there anything during these discussions, or writing, that changed or illuminated how you understand any of the following: the genetic code, t-RNAs, mRNAs, definition of a gene, coding & non-coding strands or anything else related to the topic? In other words, did any lightbulbs go off for you during the group quiz discussion or during your work on this extra-credit opportunity? Note, there is not a right answer here-you can say "nothing helped to illuminate my thinking about any of this" if that is, in fact, true!) Question to write about: A mutation in the DNA of a gene produced a UGA stop codon in the middle of the mRNA encoded by the gene. In the same cell a second mutation occurred that leads to a single nucleotide change in a tRNA that allowed the correct translation of the protein. This is an example of what is called "second site suppression". The second mutation "suppresses" the defect caused by the first mutation. The altered tRNA translates the UGA as tryptophan. What nucleotide change has likely occurred in the non-template (i.e. coding) strand of the mutant tRNA gene? (You may ignore the effects of wobble.) B. C to T A. G to A Answer: B C. A to G D. C to GExplanation / Answer
Hi,
The question can be reframed as below:
The mRNA is transcribed by DNA in regular manner. But a single nucleotide mutation occured in the mRNA that added a stop codon in the middle of the coding region. This will result in truncated amino acid sequence. However, another mutation occured in the anticodon arm of the tRNA, which read this stop codon as codon for tryptophan. This allows for complete translation of the mRNA. Can you determine what base in the anticodon arm has changed or mutated such that the stop codon effect is neutralized?
Answer:
The codon on the mRNA : UGA
The correct anticodon in tRNA for this triplet = ACT
However, a mutation in ACT should confuse it to trytophan instead of stop codon.
The tryptophan is coded by triplet UGG on mRNA.
The codon on mRNA for stop codon = UGA
The code on DNA for stop codon = ACT
The codon on mRNA for tryptophan = UGG
The code on the DNA for tryptophan codon = ACC
This means on the DNA, the ACC has changed to ACT so as to add a stop codon in the middle. The base change of C to T in third position is responsible for this mutation. Option B is the answer.