The rough endoplasmic reticulum has on it ribosomes, which are small, round organelles whose function it is to make those proteins. Sometimes, when those proteins are made improperly, the proteins stay within the endoplasmic reticulum. They're retained and the endoplasmic reticulum becomes engorged because it seems to be constipated, in a way, and the proteins don't get out where they're suppose to go. Then there's the smooth endoplasmic reticulum, which doesn't have those ribosomes on it.
And that smooth endoplasmic reticulum produces other substances needed by the cell. So the endoplasmic reticulum is an organelle that's really a workhorse in producing proteins and substances needed by the rest of the cell. Endoplasmic Reticulum Rough. Some of the proteins are delivered into the lumen or space inside the ER whilst others are processed within the ER membrane itself.
In the lumen some proteins have sugar groups added to them to form glycoproteins. Some have metal groups added to them. It is in the rough ER for example that four polypeptide chains are brought together to form haemoglobin. Protein quality control section It is also in the lumen that an amazing process of quality control checking is carried out. Proteins are subjected to a quality control check and any that are found to be incorrectly formed or incorrectly folded are rejected.
These rejects are stored in the lumen or sent for recycling for eventual breakdown to amino acids. A type of emphysema a lung problem is caused by the ER quality control section continually rejecting an incorrectly folded protein. The protein is wrongly folded as a result of receiving an altered genetic message. The required protein is never exported from the lumen of rough ER. Rigorous quality control plays a part in cystic fibrosis A form of cystic fibrosis is caused by a missing single amino acid, phenylanaline, in a particular position in the protein construction.
The protein might work well without the amino acid but the very exacting service provided by the quality control section spots the error and rejects the protein retaining it in the lumen of the rough ER. In this case the customer the person with cystic fibrosis loses out completely due to high standards when a slightly poorer product would have been better than no product at all.
They are conveyed in vesicles or possibly directly between the ER and Golgi surfaces. It is found fairly evenly distributed throughout the cytoplasm. Smooth ER is devoted almost exclusively to the manufacture of lipids and in some cases to the metabolism of them and associated products. In liver cells for example smooth ER enables glycogen that is stored as granules on the external surface of smooth ER to be broken down to glucose.
Smooth ER is also involved in the production of steroid hormones in the adrenal cortex and endocrine glands. Smooth ER — the detox stop Smooth ER also plays a large part in detoxifying a number of organic chemicals converting them to safer water-soluble products.
Large amounts of smooth ER are found in liver cells where one of its main functions is to detoxify products of natural metabolism and to endeavour to detoxify overloads of ethanol derived from excess alcoholic drinking and also barbiturates from drug overdose. To assist with this, smooth ER can double its surface area within a few days, returning to its normal size when the assault has subsided. The contraction of muscle cells is triggered by the orderly release of calcium ions.
These ions are released from the smooth endoplasmic reticulum. Cytoskeleton — the movers and shapers in the cell.
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