Which small particles of RNA and protein in the cytoplasm produce proteins by following instructions from DNA?

• A. Ribosome
• B. Endoplasmic Reticulum
• C. Golgi apparatus
• D. Nucleus

Answer: (A)

Ribosomes are the molecular machines that actually make proteins by translating genetic instructions. They’re tiny particles made of ribosomal RNA and proteins and float freely in the cytoplasm (or are attached to the rough endoplasmic reticulum). The DNA in the nucleus is first transcribed into messenger RNA, which exits to the cytoplasm. The ribosome reads this mRNA and, with tRNA bringing in amino acids, strings them together to form a polypeptide. So these ribosomes follow the DNA’s instructions via the mRNA to build proteins. The endoplasmic reticulum helps fold and modify proteins and can transport them, the Golgi apparatus packages and ships them, and the nucleus houses the DNA itself, but the actual production of proteins in the cytoplasm is done by ribosomes.