Amino acids are attached to the CCA tail of a tRNA. These are found at the 3' end of tRNA molecules and are important for recognition by aminoacyl tRNA synthetases (enzymes that actually attach the amino acids to the tRNA). The anticodon loop, as the name suggests, contains the anticodon, which will be important during translation for recognizing mRNA sequences. The D-loop and the variable loop are other portions of the tRNA that are important for maintaining structure and recognition.

Tetracycline blocks the binding of aminoacyl tRNA to the A site of the ribosome.

Cyclohexamide blocks the translocation reaction on ribosomes.

Rifamycin blocks the initiation of RNA chains by binding to RNA polymerase.

Chloramphenicol blocks the pepidyl transferase reaction on the ribosome.

The ribosomal complex has three sites where tRNA moelcules can be oriented during the process of translation: the A site, the P site, and the E site. During polypeptide elongation, a tRNA with an attached amino acid will enter at the A site. It will then move to the P site, now holding the growing polypeptide chain. All tRNAs no longer holding an amino acid will exit the ribosome at the E site.

In order to make sure that the proper amino acid is added to the growing polypeptide chain, an anticodon found on the tRNA carrying the amino acid must be a match for the codon found on the mRNA.

Ribosomal proteins are translated in the cytoplasm and rRNA genes are transcribed in the nucleolus. Following protein translation, these proteins enter the nucleus through nuclear pores and localize to the nucleolus. Here, transcribed rRNA associates with the ribosomal proteins to form the 60S and 40S eukaryotic ribosomal subunits. Prokaryotes have 50S and 30S subunits. The ribosomal subunits then translocate to the cytoplasm where they join together to form fully functional ribosomes.

The correct answer is there are three sites. A site binds aminoacyl-tRNA, P site binds peptidyl-tRNA, E site binds free tRNA before ribosomal exit.

Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.

5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.

在翻译中有四个阶段:激活,initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.

Modification of the transcript occurs after translation has been completed.

Viruses utilize IRES to allow translation to occur in a 5' cap-independent manner. Translational machinery (ribosomes) are located to the IRES so that translation can occur. 5' guanine cap and 3' poly-A tails are mRNA modifications that are normally necessary to initiate translation, but are cap-dependent. The promoter regulates genes expression on the level of transcription, whereas the 5' UTR regulates translation.

The correct answer is methionine. The ATG codon triplet in a mRNA strand codes for the start of the peptide, and this first amino acid that is coded by ATG is methionine.