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Generally speaking, you should have several pages on your website, each one dedicated to a different aspect of your business. These pages may include detailed product or service descriptions, a blog section for company updates or a contact page. A major site plan will require neighborhood meetings if it results in new street connections to existing streets or to stubs within a single-family residential subdivision. 메이저사이트
Synthesis of Lipids in Smooth Endoplasmic Reticulum
Lipids are synthesized in the ER by enzymes that transfer fatty acids from coenzyme A to glycerol phosphate, forming phospholipids and other lipids. These lipids are transported to other organelles or into the cell membrane. The synthesis of lipids within the ER is regulated by the concentrations of fatty acid head groups, which are generated in the ER by enzymes such as the CTP:phosphocholine cytidylyltransferase. The lipids are also regulated by the activities of phospholipases and acyltransferases that remove or add fatty acyl chains to form complex lipid structures.
Most cells lack a large system of sER (smooth endoplasmic reticulum), but it is abundant in cells that specialize in lipid metabolism. Examples of such cells include Leydig cells in the testis, follicular cells of the ovary, and hepatocytes of the liver. Hepatocytes use their sER for lipid processing and detoxification, glycogen storage, and calcium metabolism.
The sER is also used for protein synthesis, but there are different pathways for this in each cell type.
Synthesis of Hormones in Smooth Endoplasmic Reticulum
The smooth endoplasmic reticulum (sER) is a membrane-enclosed network of tubular and sometimes branched elements that are present throughout the cytoplasm. It is different from the rough endoplasmic reticulum (RER) because it does not contain ribosomes on its cytoplasmic surface.
It is involved in a variety of metabolic processes including the synthesis of lipids, such as cholesterol and phospholipids which are found in cell membranes; steroid hormones; carbohydrate metabolism; detoxification of harmful chemicals; and storage of calcium ions. A specialized type of smooth ER, called the sarcoplasmic reticulum, is located in muscle cells; it stores and regulates the concentration of calcium ions that triggers the coordinated contraction of muscle fibers.
In cells that process a large amount of toxic chemicals, the smooth ER can quickly double in size to accommodate the increased workload. This is a response to the stress that these chemicals exert on the cell and to ensure that the toxins are metabolized and eliminated as soon as possible.
Synthesis of Nucleotides in Smooth Endoplasmic Reticulum
All eukaryotic cells have an endoplasmic reticulum (ER), a continuous membrane system that forms a series of flattened sacs within the cytoplasm and serves multiple functions, including synthesis, folding, modification, and transport of proteins. Some types of ER have distinct features that affect their function. The ER contains ribosomes attached to the membrane that specialize in synthesis of proteins with signal sequences that direct them to the ER for processing. It also contains free ribosomes that synthesize all other proteins in the cell. The ER is further divided into rough and smooth portions, which are distinguished by their physical and functional characteristics.
The protein chaperone BiP helps to pull incorrectly folded proteins posttranslationally into the ER through a protein translocator. Another ER resident protein is protein disulfide isomerase, which catalyzes the oxidation of free sulfhydryl groups on cysteines to form disulfide bonds. These bonds stabilize correctly folded proteins and assemble them into oligomeric complexes. Another ER resident is phosphatidylserine synthase, which exchanges the polar head group of polyserine for that of polyphosphate. Phosphatidylserine then translocates to the mitochondria through an ATP-driven process.
Synthesis of Proteins in Smooth Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a series of membrane-enclosed sacs and tubules that are scattered throughout the cytoplasm of eukaryotic cells. The ER contains enzymes that modify proteins and also synthesize lipids. Proteins destined for the cell membrane or secreted are assembled at organelles called ribosomes within the ER. The region of the ER that is studded with ribosomes is known as the rough endoplasmic reticulum; the area that lacks ribosomes is called smooth endoplasmic reticulum.
The smooth ER synthesizes lipids and carbohydrates for the cell, and it makes phospholipids for the plasma membrane and other organelles. It also functions as a storage site for calcium ions. A specialized form of the smooth ER, which is found only in muscle cells, is known as the sarcoplasmic reticulum. The sarcoplasmic reticulum stores and releases calcium ions in response to nerve impulses that cause muscle contraction. The sER also plays a role in lipid synthesis, carbohydrate metabolism, detoxification of medications and poisons, and regulation of the concentration of calcium ions.