What is the primary purpose of ribosome profiling (Ribo-Seq) in studying translation?

• A. ChIP-Seq identifies histone modifications.
• B. Ribosome profiling (Ribo-Seq) sequences ribosome-protected mRNA fragments to determine translation sites and ribosome density.
• C. RNA-Seq of total RNA.
• D. DNA methylation profiling.

Answer: (B)

Ribosome profiling is used to reveal which parts of mRNAs are actively being translated and how densely ribosomes occupy those regions. By treating cells so that only ribosome-protected fragments of mRNA remain and then sequencing those fragments, you get a direct readout of ribosome positions across the transcriptome. This maps translation start sites, elongation patterns, and overall ribosome occupancy, allowing you to identify which open reading frames are actually translated and to gauge translation efficiency relative to mRNA abundance. It’s distinct from ChIP-Seq, which looks at protein-DNA interactions like histone modifications; from RNA-Seq of total RNA, which measures transcript abundance but not translation; and from DNA methylation profiling, which tracks epigenetic marks.