What would happen if the 5’ methyl guanosine was not added...

What would happen if the 5’ methyl guanosine was not added to an mRNA? a. The transcript would degrade when the mRNA moves out of the nucleus to the cytoplasm. b. The mRNA molecule would stabilize and start the process of translation within the nucleus of the cell. c. The mRNA molecule would move out of the nucleus and create more copies of the mRNA molecule. d. The mRNA molecule would not be able to add the poly-A tail on its strand at the 5’ end.

What would happen if the 5’ methyl guanosine was not added to an mRNA?
a. The transcript would degrade when the mRNA moves out of the nucleus to the cytoplasm.
b. The mRNA molecule would stabilize and start the process of translation within the nucleus of the cell.
c. The mRNA molecule would move out of the nucleus and create more copies of the mRNA molecule.
d. The mRNA molecule would not be able to add the poly-A tail on its strand at the 5’ end.

Key Concepts

mRNA Capping

This process involves the addition of a modified guanine nucleotide (5’ methyl guanosine) to the 5’ end of precursor mRNA. It is one of the earliest modifications that occurs during mRNA processing and plays a critical role in protecting the mRNA molecule from enzymatic degradation, as well as serving as a recognition signal for the ribosome during the initiation of translation.

mRNA Stability

The 5’ cap contributes significantly to the stability of the mRNA by protecting it from exonucleases that could otherwise degrade the transcript once it exits the nucleus. Without the cap, mRNA molecules are vulnerable to rapid degradation, leading to a decrease in the available message for translation, thereby affecting protein synthesis.

Nuclear Export and Translation Initiation

The cap structure not only shields mRNA from degradation but also facilitates its export from the nucleus to the cytoplasm and is recognized by the cellular machinery that initiates translation. Loss of the cap would impair these processes, thereby hindering the proper translation of mRNA into proteins.

Transcript

00:01 Hi everyone, my name is eric and let's answer problem 25.

00:05 In problem 25, we are focusing on the 5 prime methyl guanocene.

00:16 Okay, and this is added to an mrna.

00:21 So first off, let's go ahead and define what this 5 prime methylguanocene is.

00:27 So this has to relate with the prepackaging of the mrna.

00:33 And so we are going to be modifying this mrna in order for it to be shipped out from the nucleus out into the cytoplasm.

00:42 So this has to do with making the mrna, and typically that is going to be located in the nucleus.

00:50 So if we present that this is a nucleus here, this nucleus is where our dna is located, right? so our dna.

00:57 And we are going to be making our mrna.

01:03 So this will be our mrna strand.

01:08 Out here is going to be the cytoplasm, and the cytoplasm is where the ribosomes are located.

01:19 These ribosomes are able to take that mrn to make protein, and then that protein will have function to do something in the cell.

01:31 In order for this mrna over here to be exiting this nucleus, it has to first cross the boundary of this membrane nucleus.

01:41 And in order to do so, it needs a few modifications so that it doesn't get degraded.

01:46 One of the modifications that is made is the addition of a 5 prime cap and additionally a poly a tail.

01:56 Now this one is a 5 prime and this is a 3 prime polya tail.

02:01 Okay, and the way this works is that this 5 prime methyl guanacine is the 5 prime cap that is found at the front of the mrna.

02:12 This allows the mrna to exit and cross this boundary, this membrane here.

02:19 Okay? and that prevents the degradation of this mrna because the machinery, the proteins, will recognize this 5 prime cap and recognize.

02:33 That it is an mrna and therefore it won't degrade this molecule so that it can be translated with the ribosomes...

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