Insulin is a protein that is produced by certain pancreatic cells and secreted into the bloodstream. (This is true.) Which of the following choices best describes the route of insulin from its production to its exit from the cell ? A. contain membrane folds called cristae, whereas chloroplasts contain disk-like vesicles in stacks called grana. B. rough ER, transport vesicles, Golgi apparatus, transport vesicles, cell membrane

B. rough ER, transport vesicles, Golgi apparatus, transport vesicles, cell membrane.

Explanation:

First insulin will be packaged in a membrane from the rough endoplasmic reticulum and then released. It will then head to the Golgi apparatus where the molecules will be morified and repackaged. Insulin will then leave the cell through exocytosis

. B. rough ER, transport vesicles, Golgi apparatus, transport vesicles, cell membrane

Explanation:

This route follows the normal pathways any synthesised protein follows during steps of  protein synthesis of  cells.

1. Because  Insulin is a peptide hormone needed out side the cells, it is synthesized by ribosomes attached to the Rough Endoplasmic Reticulum of the beta cells in the pancreas.The stimulus for secretions are elevated plasma concentration of blood sugar and amino acids. The protein   arrives to the R.ER as preproinsulin   after translation, and with the addition of disulphide bridges in the R.ER formed prosinsulin.

2.The proinsulin  are transported through the transport vesicles which makes use of the cytoskeleton of the cytosol for movements to reach the Cisternae ( golgi apparatus).

3. The Golgi bodies  packaged and modified  the proinsulin to form active insulin. and  transported these by Cisternae migration to trans-golgi reticulum.

From here they are transported to the trans-Golgi network; where they are moved  into the secretory vesicles and transport vesicles.

The transport vesicles  fused with the plasma membrane , and based on metabolic or vagus stimulation is  secreted to the  blood stream through  Exocytosis.

hammurabi rulers

good lesson