Biochemistry

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Question

This question has been answered by 56 people and has an average rating of 3.47 (based on 32 ratings)

This is the three dimensional structure of the triose phosphate isomerase protein found in maize.

 

no description

 

The gene for this spans over 3400 bp of DNA. However, the mature mRNA is only 1050 nucleotides long. Why is this? 

Alternatives

The contributor suggests B is the correct option
Option Alternative First
answers
 Confirmed
answers
A

The loss of introns makes mature mRNA much smaller than the primary transcript.

4 (7.14%)

0 (0.00%)
B

This is due to the splicing of introns and exons, which are sites where the mRNA precursor is cut and joined. During the process introns are lost, causing a significant reduction in the size of the primary transcript versus the mature mRNA.

32 (57.14%)

26 (100.00%)
C

The loss of exons makes mature mRNA a fraction of the size of the primary transcript.

3 (5.36%)

0 (0.00%)
D

The introns and exons, also known as splice sites, are where the mRNA is cut and joined causing a significant reduction in size from the primary transcript to the mature mRNA. 

8 (14.29%)

0 (0.00%)
E

This is due to the splicing of introns and exons, which are sites where the mRNA precursor is cut and joined. During the process exons are lost, causing a significant reduction in the size of the primary transcript versus the mature mRNA.

9 (16.07%)

0 (0.00%)

Explanation

The following explanation has been provided relating to this question:

The introns are lost during transcription processing and the exons are kept in the mRNA. Therefore, the spliced mature mRNA is much shorter than the primary transcript which still contains the introns. 

Topics

The following topics have been indicated as being relevant to this question:

transcription, introns, exons, splicing

Comments

There are 8 comments for this question (8 top-level comments and 0 replies) As an administrator for this course, you can write comments about this question. Any comments you write will appear just like student comments. If you would like to write a special comment that is labelled as an "Administrator comment", please use the option above.
Written: 6:53pm, 23 SepAuthor has: 2283 points and 12 badges

GREAT question - love how it is different from the others (visual representation) 

Question is quite tricky, requires some extra thinking, but overall makes a lot of sense :)

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Written: 12:30am, 24 SepAuthor has: 1607 points and 9 badges

This is such a challenging and fantastic question as it required an awful lot of pondering and research. It is also significantly different in comparison to other questions as it provided a visual illustration to represent the question. Nice work!

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Written: 1:33pm, 27 SepAuthor has: 624 points and 7 badges

I loved this question because it was quite tricky and provided visual information to support the question. I had to go over notes and do a bit of research in order to answer this one. 

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Written: 1:37pm, 27 SepAuthor has: 723 points and 6 badges

Great question that applies theoretical knowledge to an example

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Written: 3:39pm, 27 SepAuthor has: 2494 points and 15 badges

Well written question with great use of the visual stimulus. The explanation is appropriate and clear, however the chosen option that is correct does not reflect the understanding of what is explained.

 

Option B: This is due to the splicing of introns and exons, which are sites where the mRNA precursor is cut and joined. During the process introns are lost, causing a significant reduction in the size of the primary transcript versus the mature mRNA.

Indeed, during the process introns are lost however, the wording of this section creates ambiguity in the answer. The word 'versus' in this case implies that the reduction in size occurs to the primary transcript itself IN COMPARISON TO the mature mRNA. Rather than saying this, it would be better to reword it as '...causing a significant reduction in the size of the primary transcript. As a result, the mature mRNA is only 1050 nucleotides long'. The mature mRNA is the product after the splicing occurs - the primary transcript/mRNA is what undergoes the splicing process. It is good to integrate the stimulus into the answer.

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Written: 9:41pm, 27 SepAuthor has: 677 points and 7 badges

Creative question supported with a great visual stimulus and the explanation provided was very clear and concise.

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Written: 10:41pm, 27 SepAuthor has: 702 points and 6 badges

I really liked this question because it made me think about the distinction in introns/exons and which are kept/lost. The difference in answers made it easy to deduce that some answers were simply not correct, but nevertheless made me recognize a key fact in the transcription process.

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Written: 7:02am, 28 SepAuthor has: 314 points and 7 badges

This is a very clearly worded question with great options for answers which successfully tested a topic of knowledge on transcription. The use of a visual stimulus was great as even though answering the question didn't require the specific use of the image, it captured attention and was relevant. Improvements could be made to the allocation of marks to the answers by taking up partial marking. This would have been easy to apply to the well-worded answers. For example, option A is partially correct as introns are in fact lost, however option B is clearly the better answer as this loss of introns reduces the size of the primary transcript rather than the mature mRNA. Thus a mark of 0.5 could be awarded to option A and 1 mark awarded to option B. 

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