Cells of the pancreas will incorporate radioactively labeled amino acids into proteins. This "tagging" of newly synthesized proteins enables a researcher to track the location of these proteins in a cell. In this case, we are tracking an enzyme that is eventually secreted by pancreatic cells. Which of the following is the most likely pathway for movement of this protein in the cell?

laboratories came to adopt the technique for protein synthesis for the purposes of answering the age-old question: exactly what role do amino acids play in proteins? Scientists Marshall Nirenberg and Heinrich Matthaei made a huge breakthrough in the answer to this fundamental question in 1961, successfully applying cell-free protein expression to make the connection between nucleotide triplets and the amino acids they encode.

Using an in vitro translation system based on E. coli, they were able to synthesize the polypeptide polyphenylalanine. From there, they were able to determine the connection between the amino acid phenylalanine and its corresponding codon UUU, essentially discovering the key to cracking the genetic code. This groundbreaking experiment would eventually lead to the deciphering of all the remaining amino acid codons and laid the foundation for the wide variety of translation biology systems that are available today

Cell-free expression begins with crude extracts generated from cultured cells that are typically engaged in a high rate of protein synthesis, such as immature red blood cells (reticulocytes). These crude extracts are depleted of their endogenous DNA and mRNA, and the cell lysate is subsequently supplemented with macromolecular components required to perform translation, including ribosomes, tRNAs, aminoacyl-tRNA synthetases and initiation, elongation and termination factors.