Smooth endoplasmic reticulum differs from the rough endoplasmic reticulum in not having ribosomes on its surface. The smooth endoplasmic reticulum (SER) extends from the rough ER and forms a network of membrane tubules. The function of the smooth ER is to serve as a site for the synthesis of lipids, fatty acids, and steroids such as estrogens and testosterone.
Enzymes for the synthesis of these diverse biomolecules are present in smooth ER. The smooth ER present in the muscle cells is called the sarcoplasmic reticulum. It stores the calcium ions which are released into the sarcoplasm of muscle cells during muscle contraction.
Sinh vật nhân sơ chỉ có một RNA Polymerase, trong khi sinh vật nhân chuẩn có ba (RNA Polymerase I, phiên mã rRNA; II, phiên mã mRNA; và III, phiên mã tRNA).
Our lymphatic systems act to drain lymph from our tissues, empties and redirects it back to the bloodstream. Therefore, blood vessels remove the venom which is to be drained by our lymphatic system, cycle repeats until no venom is left.
