Golgi body apparatus, RER + SER

Question 1

Give the basic key idea needed to understand this

Answer 1

Once a protein has been formed it has to fold into its 3 dimensional shape which is then modified further, which is critical for the function of that protein.
Proteins also have different destinations e.g proteins function in the cytoplasm, some are sent to the cell membrane and some are secreted from the cell e.g hormones or antibodies.

Question 2

Describe the function of the rough endoplasmic reticulum

Answer 2

• RER is involved in targeting proteins to their different destinations. This consists of sheets of membranes forming flattened sacs called cisternae which contain a range of different enzymes.
• These cisternae are covered with ribosomes ( protein synthesis) where translation takes place for proteins which are secreted from the cell, and ones that are used for the cell membrane and for lysosomes.

Question 3

Describe the role of the RER in protein synthesis

Answer 3

When mRNA is attached to a ribosome on the outside of the RER, translation is taking place. The growing polypeptide chain then passes through the membrane into the lumen of the RER, and then in the lumen the polypeptide chain folds into its tertiary structure, now it makes its way through the rough ER and is modified and packaged into vesicles.

Question 4

Describe the role of the golgi body in protein synthesis

Answer 4

Vesciles that have been packaged in the rough ER go through the golgi body where they are modified further, and eventually the protein has reached its final structure, named a functional protein.
These are now packaged as vesicles again and fuse with the cell membrane so they can be secreted from the cell.

Question 5

Describe the function of the SER

Answer 5

To make and store both lipids and carbohydrates, then they pass through the golgi apparatus to be modified.