Endoplasmic Recticulum

Question 1

INTRO

Answer 1

The endoplasmic reticulum (ER) plays a key role in the modification of proteins and the synthesis of lipids.
It consists of a network of membranous tubules and flattened sacs.
The discs and tubules of the ER are hollow, and the space inside is called the lumen.

Question 2

RER

Answer 2

The rough endoplasmic reticulum (rough ER) gets its name from the bumpy ribosomes attached to its cytoplasmic surface.
As these ribosomes make proteins, they feed the newly forming protein chains into the lumen.
Inside the ER, the proteins fold and undergo modifications, such as the addition of carbohydrate side chains. These modified proteins will be incorporated into cellular membranes—the membrane of the ER or those of other organelles—or secreted from the cell.
If the modified proteins are not destined to stay in the ER, they will be packaged into vesicles, or small spheres of membrane that are used for transport, and shipped to the Golgi apparatus. The rough ER also makes phospholipids for other cellular membranes, which are transported when the vesicle forms.
Since the rough ER helps modify proteins that will be secreted from the cell, cells whose job is to secrete large amounts of enzymes or other proteins, such as liver cells, have lots of rough ER.

Question 3

SER

Answer 3

The smooth endoplasmic reticulum (smooth ER) is continuous with the rough ER but has few or no ribosomes
FUNCTIONS;
-Synthesis of carbohydrates, lipids, and steroid hormones
-Detoxification of medications and poisons
-Storage of calcium ions

In muscle cells, a special type of smooth ER called the sarcoplasmic reticulum is responsible for storage of calcium ions that are needed to trigger the coordinated contractions of the muscle cells.

There are also tiny “smooth” patches of ER found within the rough ER. These patches serve as exit sites for vesicles budding off from the rough ER and are called transitional ER