The cell organelle responsible for the synthesis of protein is the

Step 1: Analyze the question The question asks which cell organelle makes (synthesizes) protein.

Step 2: Explain the concept Protein synthesis (translation) happens when amino acids are joined together in the order specified by messenger RNA (mRNA). The organelle that does this is the ribosome, made of ribosomal RNA (rRNA) and proteins. Ribosomes can be:

• Free in the cytoplasm, making proteins used inside the cell.
• Attached to the rough endoplasmic reticulum, making proteins for export or for membranes.

Step 3: Check each option

• A. Centriole: helps organize spindle fibres during cell division in animal cells. It does not make protein.
• B. Vacuole: stores water, salts, and food, and helps maintain turgor in plant cells. It does not make protein.
• C. Plastid: includes chloroplasts (photosynthesis) and leucoplasts (storage). Its role is food production or storage, not protein synthesis in general.
• D. Ribosome: the site of protein synthesis. ✔

Step 4: Answer The correct option is D. ribosome.

Exam tip: Link the words: Ribosome = Read mRNA and build Protein. Another useful set to memorize:

• Mitochondria: energy (ATP)
• Ribosome: protein synthesis
• Golgi apparatus: packaging and secretion
• Lysosome: digestion