LIFE SCIENCE

Detailed explanation-1: -Bound ribosomes usually produce proteins that are used within the plasma membrane or are expelled from the cell via exocytosis.

Detailed explanation-2: -Protein synthesis Synthesis of new proteins starts in the nucleus, where ribosomes get their instruction to begin the process. Sections of DNA (genes), encoding a specific protein, are copied over to messenger RNA (mRNA) strands in a process called transcription.

Detailed explanation-3: -Proteins are assembled at organelles called ribosomes. When proteins are destined to be part of the cell membrane or exported from the cell, the ribosomes assembling them attach to the endoplasmic reticulum, giving it a rough appearance.