V. SHORT ANSWER: 2X3=6
1. What are the functions of endoplasmic reticulum?
Answers
Answer:
Explanation:
The endoplasmic reticulum can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function.
Answer:
The endoplasmic reticulum (ER) is a large, dynamic structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. The diverse functions of the ER are performed by distinct domains; consisting of tubules, sheets and the nuclear envelope
Explanation:
Protein synthesis requires localization of ribosomes to the cytosolic face of the ER, and the canonical pathway that regulates protein synthesis involves co-translational docking of the mRNA:ribosome complex on the ER membrane.
While the ER is a major site of protein synthesis, it is also a site of bulk membrane lipid biogenesis [4], which occurs in the endomembrane compartment that includes the ER and Golgi apparatus. Proteins and phospholipids, which are the major lipid component of membranes, are transferred and biochemically modified in the region of the ER that is in close juxtaposition to the Golgi apparatus
The typical cytosolic concentration of Ca2+ is ~100 nM, while the Ca2+ concentration in the lumen of the ER is 100–800 μM, and the extracellular Ca2+ concentration is ~2 mM [6, 30]. The ER contains several calcium channels, ryanodine receptors and inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) that are responsible for releasing Ca2+ from the ER into the cytosol when intracellular levels are low [6]. Ca2+ release occurs when phospholipase C (PLC) is stimulated through G protein-coupled receptor (GPCR) activation [31] and cleaves phosphatidylinositol 4,5 bisphosphate (PIP2) into diacyl-glycerol (DAG) and IP3, which can then bind the IP3R leading to Ca2+ release and transient increase in intracellular Ca2+ levels