what is similarity between sarcoplasmic reticulum and RER
Answers
A microtubule is a cylindrical tube made of subunits of protein called tubulin. Microtubules don’t synthesize anything. They function in a cell’s physical support and as trackways, like monorails, for the transport of materials from place to place in a cell (including separation of anaphase chromosomes). This transport is achieved by motor proteins that “walk” along the microtubules carrying a cargo of molecules or organelles. Microtubules also form the core (axoneme) of cilia and flagella, but here too, their roles are structural support and motility.
Endoplasmic reticulum (ER) is made of protein–phospholipid membranes similar to the plasma membrane at the cell surface. Some regions of it called rough ER are studded with ribosomes and consist of flat spaces called cisternae enclosed between parallel membranes. Other parts called smooth ER are more tubular in shape, more branched, and lack ribosomes. Both rough and smooth ER are parts of the same organelle—just different regions of it, developed in different proportions to each other in relation to the function of the cell. Both types, unlike microtubules, are involved in synthesizing organic molecules. Smooth ER, for example, is highly developed in cells that synthesize steroids, such as cells of the gonads and adrenal cortex, whereas rough ER is more developed in cells that synthesize proteins, such as the cells of of digestive glands and the antibody-producing plasma cells. Both ER types bud off vesicles containing their products; these vesicles are carried to the Golgi complex for further processing or to the cell surface for exocytosis.