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.

There are four phases in translation: activation, 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. 

The correct answer is the internal ribosome entry site. This site is a specific nucleotide sequence that allows for translation initiation in the middle of a mRNA sequence, rather than at the 5' end, and does not require the cap-dependent elF4F initiation complex or the 5'cap. The poly(A)-binding protein complexes with the 3' end of mRNA strands during translation initiation via the cap-dependent mechanism. 

The Shine-Dalgarno sequence is the ribosomal binding site in in prokaryotic mRNA that is located around 8 bases upstream of the start codon.

Primary structure of a protein is determined by covalent peptide bonds, and corresponds to the linear sequence of amino acids before structures begin to form. Secondary structure results from hydrogen bonding between the amino acid backbones to form alpha-helices and beta-sheets. Tertiary structure is formed when functional groups of the amino acids interact, either by hydrogen bonding, hydrophobic interactions, or disulfide bridge formation. Tertiary structure is associated with the three-dimensional structure of a single polypeptide chain. Quaternary structure forms when multiple polypeptide chains interact to build a multi-subunit structure.

Leucine zippers are domains that allow for the binding of DNA. The question is essentially asking, "which of these proteins are capable of binding DNA?"

Proteases cleave proteins, lipases hydrolyze lipids, and transmembrane proteins interact with membranes. Transcription factors are the only given proteins that bind DNA and, therefore, are much more likely to contain leucine zipper domains than the other options.