Question

In both prokaryotes and eukaryotes, initiation of translation usually

a. begins immediately upstream of a Shine-Dalgarno sequence.
b. requires the action of release factors, which cause the small and large subunits of a ribosome to associate with one another.
c. requires the action of initiation factors.
d. begins at a UAG codon downstream of the 5’ UTR of an mRNA molecule.
e. begins only after ubiquitin has been added to the mRNA molecule to be translated.

Answer 1

c. requires the action of initiation factors.

Step-by-step explanation:

Transcription is the process by which a fragment of DNA (e.g., a gene) is used as a template to create a complementary RNA molecule, usually a messenger RNA (mRNA) molecule which is then used to synthesize a polypeptide chain (i.e., a protein) in the ribosomes by a process called translation. Initiation factors are proteins capable of binding the ribosome in order to promote (or prevent) the initiation of translation. In prokaryotic cells, the initiation factors IF1, IF2 and IF3 (IFs) are required for the selection and the quantity of the protein produced. In eukaryotic cells, translation initiation occurs when an initiator tRNA, 40S, and 60S ribosomal subunits are assembled by eukaryotic initiation factors (eIFs) into an 80S ribosome on the initiation codon of an mRNA. In eukaryotes, translation initiation is promoted and regulated by at least twelve eIFs (e.g., eIF1, eIF1A, eIF2, eIF3, eIF4, eIF5, eIF5A, eIF5B, etc) which are composed of many polypeptides.