The Endoplasmic Reticulum (ER) is a series of interconnected membranous sacs and tubules that folds in on itself to create an internal space called LUMEN. The Endoplasmic Reticulum collectively synthesis and modifies proteins and lipids. However, these two functions are performed by different areas of the ER; the Smooth ER and Rough ER.
The rough endoplasmic reticulum (RER) is so named because the ribosomes (molecules in charge of protein production) is attached to its cytoplasmic surface giving it a studded appearance when viewed through an electron microscope. Ribosomes transfer their newly synthesized proteins into the lumen of the RER where they undergo structural modifications, such as folding or the acquisition of side chains called Glycosylation. These modified proteins will be incorporated into cellular membranes (the membrane of the ER or those of other organelles) or secreted from the cell (such as protein hormones, enzymes ). . Proteins made in the rough endoplasmic reticulum as destined to either be a part of a membrane, or to be secreted via transport vesicles that buds from the RER's membrane out of the cell. Since the RER is engaged in modifying proteins (such as enzymes, for example) that will be secreted from the cell, the RER is abundant in cells that secrete proteins.
The smooth endoplasmic reticulum (SER) is continuous with the RER but has few or no ribosomes on its cytoplasmic surface. The smooth endoplasmic reticulum makes lipid and steroids instead of being involved in protein synthesis.
The main way in which <span>a decrease in the number of songbirds might be expected to affect the trees in a northern forest is that the would be overrun with more instincts due to a lack or predators. </span>
