Unit 1: Movement of Proteins

Question 1

Summary of the movement of a protein:

Answer 1

A protein is made at a ribosome on the RER, the pathway it takes from here is:
Ribosome on ER -> Lumen of ER -> Vesicle -> Golgi apparatus -> Vesicle -> Other Membranes

Question 2

Where do proteins go after the ER?

Answer 2

After going through the lumen of the ER, they are transported by vesicles that bud off from the ER and fuse with the Golgi apparatus

Question 3

What happens to proteins once they reach the Golgi apparatus?

Answer 3

Proteins move through the Golgi apparatus on vesicles, as proteins do this they undergo a post-translational modification.

Question 4

What happens to the proteins after the Golgi apparatus?

Answer 4

Vesicles take proteins to the plasma membrane and lysosomes. Vesicles move along microtubules to other membranes and fuse with them in the cell.

Question 5

What is another example of post translational modification?

Answer 5

Proteolytic cleavage. Digestive enzymes are one example of secreted proteins that require proteolytic cleavage to become
active.

Question 6

What is the major post-translational modification for proteins as they move through the Golgi apparatus?

Answer 6

The addition of carbohydrate groups is the major modification.