What is the history of smooth endoplasmic reticulum?
At first the smooth endoplasmic reticulum appears in long arrays immediately beneath the plasma membrane. Evidence shows that during meiotic divisions some of these long arrays of smooth endoplasmic reticulum become very well organized into plasma membranes of the resulting daughter cells.
Who discovered the smooth endoplasmic reticulum?
Keith Porter
ER discovered by Emilio Veratti in the year of 1902 as Sarcoplasmic Reticulum in muscle fibers which is similar to ER in other cells (Veratti, 1961). Fifty years later, this new organelle was first visualized through electron microscopy (EM) by Keith Porter and termed it as “endoplasmic reticulum” (Porter, 1953).
What is the origin of endoplasmic reticulum?
Dallmer el al., 1966, reported that the endoplasmic reticulum is originated from the plasma membrane by invagination giving rise to a canalicular system. But De Robertis et al., 1970, suggested that the endoplasmic reticulum originates from the nuclear envelope which it resembles physically and chemically.
How old is the endoplasmic reticulum?
Brief history of the endoplasmic reticulum The history of the endoplasmic reticulum began in 1945 when Porter, Claude, and Fullam [1] observed vesicle-like bodies in cell culture studies using electron microscopy. These elements had a size that varied between 100 and 150 mμ.
What is the main function of smooth endoplasmic reticulum?
The smooth endoplasmic reticulum functions in many metabolic processes. It synthesizes lipids, phospholipids as in plasma membranes, and steroids. Cells that secrete these products, such as cells of the testes, ovaries, and skin oil glands, have an excess of smooth endoplasmic reticulum.
Why is the smooth ER important?
The smooth ER is involved in the synthesis of lipids, including cholesterol and phospholipids, which are used in the production of new cellular membrane. In certain cell types, smooth ER plays an important role in the synthesis of steroid hormones from cholesterol.
When was the smooth ER discovered?
1902
Discovery of Smooth Endoplasmic Reticulum French cytologist Charles Garnier and others are said to have observed ER under light microscopy as early as 1902.
Where is smooth ER found?
The smooth endoplasmic reticulum like the rough endoplasmic reticulum is connected to the nuclear envelope. The smooth endoplasmic reticulum comprises tube-like structure located near the cell periphery. These tubules or tubes sometimes branch forming a network that is reticular in appearance.
Where is smooth endoplasmic reticulum produced?
Cells that secrete these products, such as cells of the testes, ovaries, and skin oil glands, have an excess of smooth endoplasmic reticulum. The smooth endoplasmic reticulum also carries out the metabolism of carbohydrates and steroids.
What is the smooth endoplasmic reticulum made of?
The smooth endoplasmic reticulum is primarily composed of three-dimensional polygonal networks of tubules called cisternae. They are about 50 nm in diameter in mammals and 30 nm in diameter in yeast.
How big is the smooth endoplasmic reticulum?
about 50 nm
The smooth endoplasmic reticulum is primarily composed of three-dimensional polygonal networks of tubules called cisternae. They are about 50 nm in diameter in mammals and 30 nm in diameter in yeast.
What would happen without the smooth ER?
The smooth ER has an important role in lipid and steroid synthesis, it is a storage for intracellular calcium as well. Without ER in the skeletal muscle fibers couldn’t happen muscle contraction. In the absence of these cellular mechanisms the cell would probably die.
What is smooth endoplasmic reticulum?
Endoplasmic Reticulum (Smooth) =. Endoplasmic reticulum is a network of membranes inside a cell through which proteins and other molecules move. Proteins are assembled at organelles called ribosomes. When proteins are destined to be part of the cell membrane or exported from the cell, the ribosomes assembling them attach to
What is the history of endoplasmic reticulum?
In 1945, Porter, Claude and Fullman with the help of electron microscope noted a delicate membranous network in the cytoplasm. It was later called endoplasmic reticulum (ER) by Keith Porter in 1953. The ER originally seemed to be confined to the endoplasm of the cell, hence its name.
Where is the endoplasmic reticulum found in a cell?
The membranes of the ER are continuous with the outer nuclear membrane. The endoplasmic reticulum occurs in most eukaryotic cells, but is absent from red blood cells and spermatozoa . There are two types of ER: rough endoplasmic reticulum ( RER) and smooth endoplasmic reticulum ( SER ).
Why is the smooth endoplasmic reticulum called the transitional ER?
In most cells the smooth endoplasmic reticulum (abbreviated SER) is scarce. Instead there are areas where the ER is partly smooth and partly rough, this area is called the transitional ER. The transitional ER gets its name because it contains ER exit sites.