splicesomes and one gene one product mantra

[Bomikepa]

so i keep reading that eukaryotes have one product per RNA transcript but once the introns are removed the introns can rearrange in different arrangements to form transcripts. Doesn't this violate the whole one gene one product deal because with rearranged introns you could code for many different products?

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[Addallat]

you have to think dogma DNA to RNA to protein


the gene is DNA which codes for a primary RNA transcript that'll code for a protein

however, you can have different protein products with differential splicing of the prespliced RNA (hnRNA) leading to different protein products (splicing effects the RNA, not the gene itself)


monocistronic means one gene codes for one protein product (doesn't have anything to do with splicing since splicing refers to hnRNA INTRONS being removed; doesn't effect DNA [i.e the gene])

 

[Bomikepa]

you have to think dogma DNA to RNA to protein


the gene is DNA which codes for a primary RNA transcript that'll code for a protein

however, you can have different protein products with differential splicing of the prespliced RNA (hnRNA) leading to different protein products (splicing effects the RNA, not the gene itself)


monocistronic means one gene codes for one protein product (doesn't have anything to do with splicing since splicing refers to RNA exons being removed NOT the DNA[gene])

the exons are removed? i thought it was the introns? or are both removed? the exons are just the mrna regions that dont code for anything right?

so the RNA which has its introns removed but has not been spliced yet is called (hnRNA)?

so is that one gene one product just referencing the number of proteins ( not the type)
ie have one transcript get one protein? (actual type or protein does not matter for this concept)
and its NOT saying that one polypeptide can yield 10 proteins?

do we need to know these specific terms? i dont recall the prep book talking about hnRNA well maybe TBR would

 

[Addallat]

my bad i meant to type introns are removed

pneumonic: EXons are EXpressed so they must stay
and INtrons are kicked OUT

so the RNA which has its introns removed but has not been spliced yet is called (hnRNA)?

yes pre-spliced mRNA is known as heteronuclear RNA


so is that one gene one product just referencing the number of proteins ( not the type)

monocistronic means you will get one TYPE of primary transcript (which can undergo differential splicing to TYPEs of mRNA which TRANSLATES to protein)

Quantity comes in to play depending on the half-life of your mRNA which is what gets TRANSLATED into proteins in the cytoplasm by ribosomes


do we need to know these specific terms? i dont recall the prep book talking about hnRNA well maybe TBR would

i would dedicate time to becoming comfortable with terms
you have to know your dogma very well DNA ~~~> RNA ~~~~> Protein
AND differences between prokaryotic and eukaryotic <~~~~ no such thing as prokaryotic hnRNA since prokaryotic primary transcript is good to go as soon as it's made .... i should say even while it's being made since no organelles means transcription and translation can occur right away

 

[blayne]

It is the terminology that can be confusing.

In euks, one gene can yield multiple proteins via alternative splicing/processing. The correct mantra should be 1 mRNA => 1 protein, NOT 1 gene => 1 protein. The confusion I think lies in the terminology and confusion over the difference between a primary transcript and mRNA.
- The primary transcript refers to the RNA that is transcribed before it is spliced
- An mRNA refers to a single product of alternative splicing of a primary transcript

So,
- Each gene yields a single primary transcript
- However a given primary transcript can be spliced up in different combinations (introns out; exons in). Each combination made by the splicesome from the primary transcript yield a different mRNA "sourced" from the gene
- Each mRNA will yield only one protein

So in sum:
1 gene => 1 primary transcript => Multiple mRNAs => Multiple proteins (where the multiple mRNAs to multiple proteins is 1-to-1 relationship)