Translation Test Question

[Connman_77]

I am a 9th grader in a high school biology class. My teacher is very bright, but there are lots of times where he writes a test question that is wrong because his correct answer is not the most correct answer. When we get our tests back we can debate with him over a question to see if he will give us the point. I have reversed his decision on 3 questions this year, but this latest one i could not get him to budge on. Normally i would let it go, but i am sure i was right. Here is the questions (to the bets of my memory).

Which of the following identifies the molecules involved in the process of translation
a. mRNA only
b. mRNA and rRNA only
c. mRNA, rRNA, and tRNA
d. mRNA, and tRna only

his correct answer was c, but i believe it is d. I mentioned that the only thing our text book said about rRNA was that it was what made up the ribosomes. He then said that teaching could not occur without the building we are in, at which point i thought for sure i had won the argument, because i quickly retorted "and the bricks would be like the rRNA, and bricks are the most imporant ingredient in education." In the end he wouldnt give me the point. most of my peers said that i wasnt right, but i definately won the argument. Anyway. What is the most correct answer, c or d?

[zalaskit]

Hmm... I can see both sides really, i would say that mRNA and tRNA have the most 'active' roles, but as he said, without rRNA, nothing much could happen. So i guess depending on how specific the Q was wanting you to be... If it were me i would have put D as well.
- just curious, what ans did the majority of your friends put? Maybe there was something said in class but not written down that may have given others an advantage.

[LilKim]

C is the correct answer.... mRNA is loaded onto the ribosome (which is largely composed of rRNA ... and some associated protiens)... However,the correct tRNA brings the amino acids to the rRNA (Ribosome) it associates with the ribosome (at the 3 sites A,P,E .. I think) and the when the correct codon is there (that matches the mRNA).. the tRNA... then it transfres the amino acid onto the growing polypeptide chain.

Therefore, without rRNA, tRNA and mRNA translation cannot occur.

hope this helps.

- KIM

p.s. I'm leaving out "details" of the process for simplicity's sake.

[Connman_77]

thanks lil kim, your reply was sadly (in the case of the text book) ten times more in depth than the text book, as far as rRNA goes. i now see that c is the correct answer, but i do not feel that it corresponded with what we were taught. And thanks zalaskit for posting.

[LilKim]

No problemmo ... glad that I could explain from a different perspective.

Best wishes with school!
- KIM

[seaseasea]

good everyone.i want to say here that some of test questions in school is not worthy of discussing detailly.because the purpose of the test questions is to improve you understand the knowledge you learned,underatanding is god.

[canalon]

Don't you think that discussion helps understanding?
First it helps remember. But most of all, it helps build knowledge. Because if you understand something, you will be able to answer to plenty of related question, when if you just know the answers to a set of question, the only thing you will ever know is simply the answers to that particular set of questions.

[LilKim]

discussion is a good thing.. hearing a seemingly difficult concept from another perspective can be sooooooo valuable (i'm saying this from personal experience)

and as a scientist...the ability to explain scientifically tecnical (or simple) concepts in "simple english" is a part of learning to communicate (to science and non-science people) .... sooo many people don't beleive this ... but it helps your writing and helps simplify presentations (i average 6 presentations each semester... )

[spark13579]

rRNA is not involved in translation. It is precisely the same thing as implying that bricks are involved in education because a school is made of bricks. I think the question was badly written. He should have said ribosome instead of rRNA.

[LilKim]

ribosomes are ar composed of both rRNA and protiens (the ribosome itself is not a protein.. but a mix of ribosomal RNA and associated proteins)

Thus, without ribosomal RNA (rRNA) tranlsation cannot occur (because without rRNA the ribosome could not exist)

[tmyg]

...actively in translation via the Kozak or Shine-Dalgarno sequence that sits upstream of the AUG codon on mRNA. rRNA has a sequence complementary to the Kozak sequence and during translation is binds and recruits the first tRNA-Met initiation factors etc etc. See: http://en.wikipedia.org/wiki/Shine-Dalgarno_sequence

[MrMistery]

You guys missed a crucial element in the discussion: 75% of the ribosome is rRNA. The current view is that the ribosome can be considered as one big ribozyme(RNA with catalitic properties)- the rRNA has the catalitic role, the proteins mostly provide structural help in keeping the ribosome intact.
Thus to education, the rRNA is more like the teacher, rather than the bricks that make up the building.
So, yes, C is deffinetly the correct answer