Processing of pre-mRNA - Video Tutorials & Practice Problems
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concept
Processing of Pre-mRNA Concept 1
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Video transcript
Hey, everyone. So in this video, we're gonna take a look at processing of pre MRN A. Now with eukaryotic species, mainly animals and plants, we're gonna say DNA contains segments called exxons and introns. Exxons are the portions that code for proteins, introns are the portions that do not. Now with transcription, we're gonna say it copies both exxons and introns to pre MRN A also called HNRN A. You might hear these two terms being used interchangeably, they're the same thing. Now, here we have a process, a period called processing where splica zones are going to process our pre MRN A to produce mature MRN A for protein synthesis. Now, here it cuts the introns out and it's going to splice the exxons together. Our memory tool here is that exxons are expressed. If we take a look here at this image, we have our gene, our informational strand, it has exons and introns involved through transcription. We still have our exxons and introns involved because we're just copying it. This is what we call our pre Mr and A or Rhnrn A. Now this starts to undergo processing and through processing with our spices and we're cutting the connections between our exxons and our introns and we're gonna remove the introns, keeping the exons around. We're gonna splice them together. Now, we have only exxons remaining at the end and this represents our mature MRN A. Now recall that when we talk about MRN A, it's gonna then move out of the nucleus to the ribosomes in the cytoplasm for protein synthesis. So just remember we're copy, copying a segment of our DNA to make this initial pre MRN A. It still needs to be processed where we get rid of the introns. So that the exxons can be expressed later on. This is important so that we are left with what's necessary for proper protein synthesis.
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example
Processing of Pre-mRNA Example 1
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Video transcript
Here it says which of the following statements is incorrect. About Hr Nahnrn A processing. Remember, HNRN A is the same thing as Pre MRN A. It's the nonprocess version of mature MRN A. Now here, Hnrn A is processed inside the nucleus in structures called spice zones. That's true in trials do not go for proteins are removed from HNRN A during processing. That is also true spliceosome join the exxons together after introns are removed. Yes, that's correct. Remember the memory tool exons are expressed, they're left behind and then spliced together so that they eventually leave the nucleus to go towards the ribosomes which are in the cytosol for protein synthesis. Hnrn A is processed to reduce its size so that it can fit inside ribosomes. Nowhere do we talk about having to cut out the introns because of spatial issues. It's not about size involved. We're just getting rid of the portions that do not code for proteins. Remember the whole point of making MRN A is that we can eventually make the necessary proteins from it. So we just gotta get rid of the portions that don't help us code for protein. So here the answer here would be option D.
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Problem
Problem
The underlined sections of the pre-mRNA below are introns. Write the sequence for mature mRNA.
5’ GCC CGA UUU AUCAGG GAC CCA 3’
A
5’ GCC UUU AUC AGG 3’
B
5’ GCC UUU GAC CCA 3’
C
5’ GCC CGA AUC AGG 3’
D
5’ GCC CGA UUU CCA 3’
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