New membrane phospholipids are synthesized by enzymes bound to the side of the membrane. a. luminal, Golgi b. extracellular, plasma c. cytosolic, endoplasmic reticulum d. cytosolic, mitochondrial

The correct option is C) cytosolic, endoplasmic reticulum

New membrane phospholipids are synthesized by enzymes bound to the cytosolic side of the endoplasmic reticulum membrane.  

Explanation:

Synthesis of proteins that are destined to membrane or exportation starts in the cytoplasm with the production of a molecule portion known as a signal aminoacidic sequence. This signal sequence is located in the amino extreme of the synthesizing protein, and when it reaches a certain length, it meets the signal recognizing particle. This particle joins the signal sequence of the protein and leads the synthesizing protein and associated ribosome to a specific region in the Rough endoplasmic reticulum where it continues the protein building. When they reach the membrane of the endoplasmic reticulum, the signal recognizing particle links to a receptor associated with a pore. Meanwhile, the ribosome keeps synthesizing the protein, and the enlarged polypeptide chain goes forward the reticulum lumen through the pore. While this is happening, another enzyme cuts the signal sequence, an action that requires energy from the ATP hydrolysis. When the new protein synthesis is complete, the polypeptide is released into the reticulum lumen. Here it also happens the protein folding (which is possible by the formation of disulfide bridges of proteins are formed) and the initial stages of glycosylation (the oligosaccharide addition).  The newly synthesized proteins get packaged into vesicles that take them to the Golgi apparatus.

In the Golgi complex, proteins suffer their final association with carbohydrates and lipids to originate glycoproteins and glycolipids. Once these processes are done, the glycoproteins and glycolipids are packaged again into new vesicles that drive them to their final destiny.

the endomembrane system i think