2. Which is not a post-translational protein modification?

2. You perform a series of experiments on the synthesis of the pituitary hormone prolactin, which is a single polypeptide chain 199 amino acids long. In the first experiment, the MRNA coding for prolactin is translated in a cell-free protein synthesizing system containing ribosomes, amino acids, tRNAs, aminoacyl-TRNA synthetases, ATP, GTP, and the appropriate initiation, elongation, and termination factors. Under these conditions, a polypeptide chain 227 amino acids long is synthesized. In a second experiment, the MRNA is translated in the same cel1-free system to which you have added SRP. In this case, translation stops after a peptide about 70 amino acids long has been produced. In a third experiment, you use the same cell-free translation system to which you have added both SRP and endoplasmic reticulum vesicles, and you find that that the prolactin MRNA now produces a polypeptide that is 199 amino acids long. A) Explain these results.

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9. Shown below is a binding pocket for a protein with a ligand bound. The ligand interacts with a serine and a valine side chain. ligand a. Briefly explain, in terms of Ka, the effect of a mutation that replaces the serine residue with a valine residue. b. Briefly explain, in terms of Kd, the effect of a mutation that alters the ligand (as seen below) binding to the original, unmutated, binding site. :0: ligand 2

7.  F. State if/how Remedios' mutation changes the amino acid sequence and describe the effect that change has, if any, on the protein.

Rank the steps of protein production in the order in which they occur. (1 = occurs first, 10 = occurs last) Initiation factors bind the small ribosomal subunit which recognizes the Shine Dalgarno sequence in the MRNA V[Choose] 6. 2 Elongation factors escort the aminoacyl 9. TRNA to the vacant A site of the ribosome 1 MRNA is spliced in the spliceosome to 10 remove introns 7 N-formylMethionine tRNA recognizes the start codon and recruits the large ribosomal [ Choose] subunit Translocation moves the uncharged tRNA to the E site and the recently extended tRNA is moved from the A site to the P site [ Choose ] DNA is transcribed into mRNA in the nucleus with the help of RNA polymerase [ Choose ] The newly formed polypeptide chain heads to the ER where it undergoes post- ( Choose] translational modifications Transcription factors bind DNA and help initiate the process of transcription [Choose ] Release factors recognize the stop codons and cause dissociation of the ribosome from ( Choose]