E. An inducer is a small molecule that binds to and inactivates a
repressor, which allows the sequence of DNA to be transcribed. An
operon is a set of prokaryotic genes in close proximity that are coor-
dinated as “all off’ or “all on.” An inducer may act to “turn on” the
operon. One classic example is the
When allolactose is
present, it serves as an inducer, and the operon is turned on, allowing
proteins to be formed that metabolize lactose.
B IO C H E M IS T R Y PE A R L S
The synthesis of proteins involves converting the nucleotide
sequence of specific regions of DNA into mRNA
followed by the formation of peptide bonds in a complex set of
reactions that occur on ribosomes
Protein synthesis is divided into three stages: initiation, elongation,
Ribosomal RNA (rRNA) is a component of the ribosomes, the protein
synthetic factories in the cell.
Many antibiotics take advantage of the differences of the rRNA
between eukaryotic and prokaryotic cells.
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Voet D, Voet JG, Pratt CW. Fundamentals of Biochemistry, upgrade ed. New York:
John Wiley, 2002.