What are Phospholipids? (Campbell Biology)
Cells as we know them could not exist without another type of lipid—phospholipids. Phospholipids are essential for cells because they are major constituents of cell membranes. Their structure provides a classic example of how form fits function at the molecular level. A phospholipid is similar to a fat molecule but has only two fatty acids attached to glycerol rather than three. The third hydroxyl group of glycerol is joined to a phosphate group, which has a negative electrical charge in the cell. Typically, an additional small charged or polar molecule is also linked to the phosphate group. Choline is one such molecule, but there are many others as well, allowing formation of a variety of phospholipids that differ from each other.
The two ends of phospholipids show different behaviors with respect to water. The hydrocarbon tails are hydrophobic and are excluded from water. However, the phosphate group and its attachments form a hydrophilic head that has an affinity for water. When phospholipids are added to water, they self-assemble into a double-layered sheet called a “bilayer” that shields their hydrophobic fatty acid tails from water.
At the surface of a cell, phospholipids are arranged in a similar bilayer. The hydrophilic heads of the molecules are on the outside of the bilayer, in contact with the aqueous solutions inside and outside of the cell. The hydrophobic tails point toward the interior of the bilayer, away from the water. The phospholipid bilayer forms a boundary between the cell and its external environment and establishes separate compartments within eukaryotic cells; in fact, the existence of cells depends on the properties of phospholipids.
Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition. https://www.pearson.com/us/higher-education/series/Campbell-Biology-Series/2244849.html
Research Article: Flip-Flop of Phospholipids in Proteoliposomes Reconstituted from Detergent Extract of Chloroplast Membranes: Kinetics and Phospholipid Specificity
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Date Published: May 7, 2019 Publisher: Public Library of Science Author(s): Daniel C. Müller, Anna Kauppi, Alicia Edin, Åsa Gylfe, Anders B. Sjöstedt, Anders Johansson, Barry S. Shea. http://doi.org/10.1371/journal.pone.0216379 Abstract: Phospholipids, major constituents of bilayer cell membranes, are present in large amounts in pulmonary surfactant and play key roles in cell signaling. Here, we aim … Continue reading
Research Article: Decrease in membrane phospholipids unsaturation correlates with myocardial diastolic dysfunction2 total views
Date Published: December 11, 2018 Publisher: Public Library of Science Author(s): Tsunehisa Yamamoto, Jin Endo, Masaharu Kataoka, Tomohiro Matsuhashi, Yoshinori Katsumata, Kohsuke Shirakawa, Naohiro Yoshida, Sarasa Isobe, Hidenori Moriyama, Shinichi Goto, Kaoru Yamashita, Hiroki Nakanishi, Yuta Shimanaka, Nozomu Kono, Ken Shinmura, Hiroyuki Arai, Keiichi Fukuda, Motoaki Sano, Tohru Minamino. http://doi.org/10.1371/journal.pone.0208396 Abstract: Increase in saturated fatty … Continue reading