Proteine production
- Thread starter yaracuy
- Start date
It’s the other way round. mRNA signals to the translational machinery via a ‘stop codon’.
Who signals RNA polymerase in selecting a particular region to produce protein ?
DNA-dependent RNA polymerases transcribe a mRNA strand starting from ~30 bp downstream of the “TATA box”.
It’s the other way round. mRNA signals to the translational machinery via a ‘stop codon’.
Let me rephrase my self :
!) time zero every thing is on stand steel
2) some signal comes to helicase to unfold ?
3) there must be a signal to open the DNA ?
4) signal to polymerase to assemble mRNA ?
5) ,+++++,,,,,,,,, produced protein
6) signal stop producing protein ?
Don't misunderstand me I am not challenging , I an just ignorant in this case
Let me rephrase my self :
!) time zero every thing is on stand steel
2) some signal comes to helicase to unfold ?
3) there must be a signal to open the DNA ?
4) signal to polymerase to assemble mRNA ?
5) ,+++++,,,,,,,,, produced protein
6) signal stop producing protein ?
Don't misunderstand me I am not challenging , I an just ignorant in this case
There is not really a simple answer for these questions. I suggest that you look through a molecular biology textbook or at least a general biology textbook for a more in-depth answer.
In short, chemical messengers induce transcription. A classic example is the lac (lactose) operon that leads to the exprssion of proteins responsible for lactose uptake and metabolism (Go to Youtube and type in lac operon there are a couple of really good videos that illustrate this process). The end result is that a DNA sequence called a promoter region is exposed and allows for the assembly of RNA polymerase. After transcription and a few modifications mRNA is the product of all this. mRNA leaves the nucleus where there are ribosomes that can translate the mRNA to peptides. Ribosomes can use the same mRNA to synthesize many copies of the same peptide until the mRNA is degraded by the cell.
Now, this gets to your second question as to what signal tells the cell to stop producing this particular protein. As long as the signal persists to allow transcription of this gene mRNA will be synthesized to replace the mRNA lost to the cells normal mRNA degradation mechanisms. In other words, there will be steady-state concentration of mRNA encoding this particular peptide (or series of peptides). If the original signal does not persist however, the rate of degradation will soon dominate the rate of mRNA production (because this rate has now beome zero or close to zero) and eventually there will be no more mRNA to encode this particular protein, thereby, ending expression of this protein.
So, this was just my attempt to simplify a pretty complicated process (This process is usually the subject of entire textbooks), but I hope this helps you.
Well, no. There is no time when a cell is at a “stand still”. (I think that is what you meant to say.) Cells are always working (and hence, turning over proteins by translation of new proteins and degradation of old ones) even when the organism as a whole is resting. At least, that is the case for metazoans like us. I think single-celled organisms, and their spores, can genuinely achieve states of ‘suspended animation’ under the right conditions.
Broadly speaking, chromatin confirmation dictates whether genes contained within that region of the chromosome can be transcribed. Following that, the active transcription of genes requires the presence of necessary specific transcription factors that complex with RNA pol or bind to enhancer elements to change DNA conformation. The production of specific transcription factor proteins needed to activate transcription of their target genes (if they don’t already exist in the cell in an inactive form) occurs in response to environmental signals or developmental programs.