Question

Which of the following is the correct sequence that a newly synthesized secretory protein would follow until it is exported from the cell?

• A. Smooth ER$\to$ Rough ER $\to$ Golgi apparatus $\to$ Cell membrane
• B. Golgi apparatus $\to$ Rough ER $\to$ Cell membrane
• C. Golgi apparatus $\to$ Smooth ER $\to$ Cell membrane
• D. Rough ER $\to$ Golgi apparatus $\to$ Cell membrane
• E. Smooth ER $\to$ Golgi apparatus $\to$ Cell membrane

Answer 1

The correct option is D Rough ER $\to$ Golgi apparatus $\to$ Cell membrane

A protein is first synthesized by ribosomes. Ribosomes are present on the Rough Endoplasmic Reticulum or RER. From RER, proteins are transported to Golgi apparatus for post-translational modification. From Golgi apparatus, proteins are packaged in membrane vesicles and transported to cells where they are engulfed by endocytosis by the invagination of the cell membrane.

Hence, the correct sequence of the path for newly synthesized protein will be RER, Golgi apparatus, Cell membrane.

So, the correct answer is 'Rough ER →→ Golgi apparatus →→ Cell membrane'.