I have a question about biology

[beom75]

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hi..everyone.
I have a quick question about biology.
I remember one bio question in real DAT. but I am not sure about the answer.
what is the order from most abundant to the least ? mRAN, tRNA, and rRNA ?
I think the oder is rRNA>mRNA>tRNA.

is that right?

 

[golfmontpoker]

hi..everyone.
I have a quick question about biology.
I remember one bio question in real DAT. but I am not sure about the answer.
what is the order from most abundant to the least ? mRAN, tRNA, and rRNA ?
I think the oder is rRNA>mRNA>tRNA.

is that right?

Yes, I think so... rRNA accounts for 60% of a ribosomes weight, and theres lots of ribosomes! mRNA is needed for protein synthesis, which happens quite often, so thats 2nd. tRNA is only needed to transfer amino acids out of the cytoplasm to the ribosome for protein synthesis. So i believe you are right

 

[RozhonDDS]

yes. the order is mRNA 50-70%, mRNA 20-40%, tRNA 10%

 

[organichemistry]

yes. the order is mRNA 50-70%, mRNA 20-40%, tRNA 10%

just figure i'd clarify... he meant to say:

yes. the order is rRNA 50-70%, mRNA 20-40%, tRNA 10%

 

[Ali-karimi]

Yes, I think so... rRNA accounts for 60% of a ribosomes weight, and theres lots of ribosomes! mRNA is needed for protein synthesis, which happens quite often, so thats 2nd. tRNA is only needed to transfer amino acids out of the cytoplasm to the ribosome for protein synthesis. So i believe you are right

Yup that's right...

 

[BrownEyes12]

I remember from biochem that the synthetic capacity (amount of each type of RNA being synthesized at any time) is approx. rRNA 60%, mRNA 30% & tRNA 10%.

But my text says the actual steady-state levels are rRNA 83%, tRNA 14% & mRNA 3%... is this what the question meant by "most abundant"?

 

[dat_student]

I remember from biochem that the synthetic capacity (amount of each type of RNA being synthesized at any time) is approx. rRNA 60%, mRNA 30% & tRNA 10%.

But my text says the actual steady-state levels are rRNA 83%, tRNA 14% & mRNA 3%... is this what the question meant by "most abundant"?

Makes no sense.. In Drosophila, the gene for neuronal connections gives rise to over 38,000 different mRNAs...3% seems a bit too low

 

[lifeisgood]

Makes no sense.. In Drosophila, the gene for neuronal connections gives rise to over 38,000 different mRNAs...3% seems a bit too low

...

 

[dat_student]

...

...????!!!! 😕

 

[BrownEyes12]

I think you guys are probably right with the order originally posted. Here is a quote from my biochem text, just for interest.

"Even though mRNA accounts for only 3% of the total RNA in E. coli, the bacterium devotes almost one-third of its capacity for RNA synthesis to the production of mRNA... The discrepancy between steady-state levels of various RNA molecules and the rates at which they are synthesized can be explained by the differing stabilities of the RNA molecules: rRNA and tRNA molecules are extremely stable, whereas mRNA is rapidly degraded after translation... half... is degraded by nucleases within 3 minutes"... but then it says that the 1/2 life of mRNA in eukaryotes is 10 times longer...

 

[golfmontpoker]

I think you guys are probably right with the order originally posted. Here is a quote from my biochem text, just for interest.

"Even though mRNA accounts for only 3% of the total RNA in E. coli, the bacterium devotes almost one-third of its capacity for RNA synthesis to the production of mRNA... The discrepancy between steady-state levels of various RNA molecules and the rates at which they are synthesized can be explained by the differing stabilities of the RNA molecules: rRNA and tRNA molecules are extremely stable, whereas mRNA is rapidly degraded after translation... half... is degraded by nucleases within 3 minutes"... but then it says that the 1/2 life of mRNA in eukaryotes is 10 times longer...

From your post, on how i interpret it (which i might be wrong), then it would be rRNA, tRNA, and mRNA... If mrna is degraded so quick, then how can mRna be so abundant? Unless its constantly being made... I dont know... Im confused from this post, dont know if its just me, but this is confusing... From what I have read its rRNA, mRNA, and tRNA

 

[RozhonDDS]

mRNA rRNA tRNA is the right answer, and thats its

 

[RozhonDDS]

mRNA rRNA tRNA is the right answer, and thats its

lol sory for my mistake there....


the correct answer is

rRNA mRNA tRNA and that is the FINAL answer

 

[nsp716]

yes. the order is mRNA 50-70%, mRNA 20-40%, tRNA 10%

Where did those %'s come from? I was thinking, in prokaryotes, you have polyribosomes (multiple ribosome units) translating one mRNA at the same time, giving you multiple copies of the same polypeptide (I read there can be about 300 ribosomes translating a single mRNA transcript in prokaryotes; in eukaryotes there can be about 10 ribosomes working on an mRNA transcript).
In this case, wouldn't you need to have many, many tRNA's available to be working on the mRNA transcript at the same time?
I know the tRNA's are reused, but it seems like there would have to be a very large pool of them in order to be able to carry out multiple translations of the same mRNA transcript.... any thoughts???

 

[RozhonDDS]

Where did those %'s come from? I was thinking, in prokaryotes, you have polyribosomes (multiple ribosome units) translating one mRNA at the same time, giving you multiple copies of the same polypeptide (I read there can be about 300 ribosomes translating a single mRNA transcript in prokaryotes; in eukaryotes there can be about 10 ribosomes working on an mRNA transcript).
In this case, wouldn't you need to have many, many tRNA's available to be working on the mRNA transcript at the same time?
I know the tRNA's are reused, but it seems like there would have to be a very large pool of them in order to be able to carry out multiple translations of the same mRNA transcript.... any thoughts???

my molecular biology text book, and any other source you look at

 

[dat_student]

...
In this case, wouldn't you need to have many, many tRNA's available to be working on the mRNA transcript at the same time?
I know the tRNA's are reused, but it seems like there would have to be a very large pool of them in order to be able to carry out multiple translations of the same mRNA transcript.... any thoughts???

#1 mRNAs are made in the nucleus. no translation in the nucleus.
#2 You're assuming that all mRNAs get translated immediately after they enter the cytoplasm. (Ribosome-mRNA complex must be formed before translation can take place)
#3 You're assuming that mRNAs quickly get degraded after translation.
#4 In the case of bacteria, tRNAs are used one at a time (i.e. at any given time, one tRNA per one mRNA that is actively being translated.)

We have so many free ribosomes in the cytoplasm and attached to ERs. So, definitely, rRNA is the most abundant.

 

[nsp716]

#1 mRNAs are made in the nucleus. no translation in the nucleus.
#2 You're assuming that all mRNAs get translated immediately after they enter the cytoplasm. (Ribosome-mRNA complex must be formed before translation can take place)
#3 You're assuming that mRNAs quickly get degraded after translation.
#4 In the case of bacteria, tRNAs are used one at a time (i.e. at any given time, one tRNA per one mRNA that is actively being translated.)

We have so many free ribosomes in the cytoplasm and attached to ERs. So, definitely, rRNA is the most abundant.

I completely agree that rRNA is most abundant. I'm just thinking that bc in prokaryotes, transcription and translation are proceeding simultaneously (my book says ribosomes attach to mRNA before transcription is even completed) there would have to be a lot of tRNA molecules to be working on one mRNA transcript, bc isnt the relationship 1 tRNA:1 codon, not 1 tRNA: 1 polypeptide?

 

[dat_student]

See below: 🙂

 

[Resonance]

It has to be rRNA > tRNA > mRNA
mRNA is the result of gene expression, acting as the template to construct the protein. The tRNA is responsible for bringing the amino acids to the RNA/ribosomal complex, which is created only after a tRNa binds to it. The smallest proteins are around 129 amino acids long. A cell with less tRNA then mRNA would be totally inefficient, you would have a large number of mRNAs needing to be expressed without anything around to accomplish it.

 

[golfmontpoker]

It has to be rRNA > tRNA > mRNA
mRNA is the result of gene expression, acting as the template to construct the protein. The tRNA is responsible for bringing the amino acids to the RNA/ribosomal complex, which is created only after a tRNa binds to it. The smallest proteins are around 129 amino acids long. A cell with less tRNA then mRNA would be totally inefficient, you would have a large number of mRNAs needing to be expressed without anything around to accomplish it.

hmmmm... 😕 This is really getting to me. rRNA > mRNA > tRNA has to be the answer! hell i dont know 😕 😕

 

[BallDontLie]

I think its rRNA>tRNA>mRNA.

I think mRNA is the lowest. You would think it would be relatively high since they are needed for protein synthesis, but their existence is very transient. As someone said before, they are quickly degraded after synthesis which helps to control gene expression. So while the cell might produce more mRNA than tRNA, the actual amount in the cell at any given point in time is quite low. I remember in my molecular biology lab we always had a tough time isolating good mRNA with our poly-T probes because there was so little of it...

 

[dat_student]

hmmmm... 😕 This is really getting to me. rRNA > mRNA > tRNA has to be the answer! hell i dont know 😕 😕

It's been a year since I last looked at this stuff:
# per cell:
tRNA > rRNA > mRNA
Weight/cell:
rRNA > tRNA > mRNA
Molecular Weight:
mRNA > rRNA > tRNA

Macromolecule Weight/cell...Molecular weight...# per cell...Diff kinds of
.......................x 10-13g..............................................molecule
Protein.............155.0...........4.0 x 104..........2,360,000.........1050
RNA.................59.0
23 S rRNA.........31.0.............1.0 x 106..........18,700............1
16 S rRNA.........16.0.............5.0 x 105..........18,700............1
5 S rRNA...........1.0..............3.9 x 104..........18,700............1
transfer............8.6..............2.5 x 104..........205,000...........60
messenger........2.4..............1.0 x 109..........1,380.............400

Reference:
http://72.14.203.104/search?q=cache...osition+of+bacteria&hl=en&gl=us&ct=clnk&cd=14

 

[nsp716]

It's been a year since I last looked at this stuff:
# per cell:
tRNA > rRNA > mRNA
Weight/cell:
rRNA > tRNA > mRNA
Molecular Weight:
mRNA > rRNA > tRNA

Macromolecule Weight/cell...Molecular weight...# per cell...Diff kinds of
.......................x 10-13g..............................................molecule
Protein.............155.0...........4.0 x 104..........2,360,000.........1050
RNA.................59.0
23 S rRNA.........31.0.............1.0 x 106..........18,700............1
16 S rRNA.........16.0.............5.0 x 105..........18,700............1
5 S rRNA...........1.0..............3.9 x 104..........18,700............1
transfer............8.6..............2.5 x 104..........205,000...........60
messenger........2.4..............1.0 x 109..........1,380.............400

Reference:
http://72.14.203.104/search?q=cache...osition+of+bacteria&hl=en&gl=us&ct=clnk&cd=14

you're the best! Does anyone know which amount was the original question even asking for?

 

[golfmontpoker]

It's been a year since I last looked at this stuff:
# per cell:
tRNA > rRNA > mRNA
Weight/cell:
rRNA > tRNA > mRNA
Molecular Weight:
mRNA > rRNA > tRNA

Macromolecule Weight/cell...Molecular weight...# per cell...Diff kinds of
.......................x 10-13g..............................................molecule
Protein.............155.0...........4.0 x 104..........2,360,000.........1050
RNA.................59.0
23 S rRNA.........31.0.............1.0 x 106..........18,700............1
16 S rRNA.........16.0.............5.0 x 105..........18,700............1
5 S rRNA...........1.0..............3.9 x 104..........18,700............1
transfer............8.6..............2.5 x 104..........205,000...........60
messenger........2.4..............1.0 x 109..........1,380.............400

Reference:
http://72.14.203.104/search?q=cache...osition+of+bacteria&hl=en&gl=us&ct=clnk&cd=14

So the answer is tRNA>rRNA>mRNA according to the number per cell, which obviously means the most abundant... Is this the final concensus according to this new information??

 

[dat_student]

you're the best! Does anyone know which amount was the original question even asking for?

good question

So the answer is tRNA>rRNA>mRNA according to the number per cell, which obviously means the most abundant... Is this the final concensus according to this new information??

Based on total weight per cell, rRNA is the most abundant: (31 + 16 + 1) / 59 = 81%
According to # per cell, tRNA is...