In the nucleus the DNA is transcribed and processed to mRNA which is translated into proteins in the cytoplasm. What happens between the time a protein is made and that when it reaches the cellular organelle in which it functions? How is it transported to its destination?

  • $\begingroup$ You want to read about transcription and translation. In the nucleus the DNA is transcribed into RNA, which then leaves the nucleus. The processing of the RNA and its translation into proteins happens in the cytosol outside the nucleus. $\endgroup$ – Chris Sep 2 '16 at 6:11
  • $\begingroup$ RNA processing also occurs inside the nucleus because the introns need to be removed (only exons code for the protein) $\endgroup$ – KingBoomie Sep 2 '16 at 8:57
  • $\begingroup$ I have changed your title and simplified (and corrected) the content of your question so that it focusses on the question you clearly wish to ask. If I have misunderstood you, please say. A good answer to this question will, in my opinion cover a range of organelles and cellular and sub-cellular locations, as well as perhaps touching on post-translational modifications. $\endgroup$ – David Sep 4 '16 at 12:11

Mature RNA is translated into proteins by the ribosomes. Ribosomes bound to the ER (endoplasmic reticulum) translate proteins that are bound for export from the cell. Free ribosomes, which are found in the cytosol, are used for structures within the the cell (http://www.brighthub.com/science/medical/articles/110037.aspx)

Proteins made on the ER are sent to the Golgi apparatus, and are packaged there for transport out of the cell. (http://www.ncbi.nlm.nih.gov/books/NBK9838/)

As far as I know, the proteins made by free ribosomes remain in the cytosol and are incorperated into certain organelles or pathways upon contact with specific other proteins or signalling molecules.

  • 1
    $\begingroup$ Mark can you add some references - we always appreciate that on this site... even for things that are very elementray $\endgroup$ – Vance L Albaugh Sep 2 '16 at 16:54
  • $\begingroup$ This answer is very limited in scope, as well as being unsupported by references, as Vance writes. I'm down-voting it until you improve it. $\endgroup$ – David Sep 4 '16 at 12:13
  • $\begingroup$ Mark: sort of (on the last point). Maybe worth mentioning en.wikipedia.org/wiki/Signal_peptide $\endgroup$ – Victor Chubukov Sep 5 '16 at 5:56
  • $\begingroup$ Sorry about that, I updated it with the references. $\endgroup$ – Mark Williamson Sep 13 '16 at 14:31

Nucleus: DNA transcribed to mRNA. mRNA is sent out of the nucleus and into the cytoplasm.

Ribosome: Site of translation. Amino acids are placed in accordance with the mRNA codon (triplet of mRNA sequences). Folding is done as the protein is formed.

Once the protein is complete, the golgi apparatus is responsible for packaging and exporting it.

  • $\begingroup$ try adding some external sources to back up your claims - i know it may seem like this is basic knowledge, but it is good practice for others to be able to follow your answer and rationale. $\endgroup$ – Vance L Albaugh Sep 3 '16 at 12:49
  • $\begingroup$ This is an incomplete answer as the Golgi is only involved in the processing of secreted or membrane proteins. $\endgroup$ – David Sep 4 '16 at 8:50

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