Ribosomes: Factories of Proteins (Campbell Biology)
Ribosomes, which are complexes made of ribosomal RNAs and proteins, are the cellular components that carry out protein synthesis. (Note that ribosomes are not membrane-bounded and thus are not considered organelles.) Cells that have high rates of protein synthesis have particularly large numbers of ribosomes as well as prominent nucleoli, which makes sense, given the role of nucleoli in ribosome assembly. For example, a human pancreas cell, which makes many digestive enzymes, has a few million ribosomes.
Ribosomes build proteins in two cytoplasmic locales. At any given time, free ribosomes are suspended in the cytosol, while bound ribosomes are attached to the outside of the endoplasmic reticulum or nuclear envelope. Bound and free ribosomes are structurally identical, and ribosomes can play either role at different times. Most of the proteins made on free ribosomes function within the cytosol; examples are enzymes that catalyze the first steps of sugar breakdown. Bound ribosomes generally make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell (secretion). Cells that specialize in protein secretion—for instance, the cells of the pancreas that secrete digestive enzymes—frequently have a high proportion of bound ribosomes.
Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition. https://www.pearson.com/us/higher-education/series/Campbell-Biology-Series/2244849.html
Date Published: November 3, 2016 Publisher: Public Library of Science Author(s): Anupama Yadav, Aparna Radhakrishnan, Anshuman Panda, Amartya Singh, Himanshu Sinha, Gyan Bhanot, Michael Polymenis. http://doi.org/10.1371/journal.pone.0166021 Abstract: The ribosome is an ancient machine, performing the same function across organisms. Although functionally unitary, recent experiments suggest specialized roles for some ribosomal proteins. Our central thesis is … Continue reading
Date Published: February 4, 2011 Publisher: Public Library of Science Author(s): Andrej Trauner, Mark H. Bennett, Huw D. Williams, Vladimir Uversky. http://doi.org/10.1371/journal.pone.0016273 Abstract: We report the development of a rapid chromatographic method for the isolation of bacterial ribosomes from crude cell lysates in less than ten minutes. Our separation is based on the use of strong … Continue reading
Date Published: January 29, 2018 Publisher: Public Library of Science Author(s): Alon Diament, Anna Feldman, Elisheva Schochet, Martin Kupiec, Yoav Arava, Tamir Tuller, John McCarthy Abstract: Ribosome queuing is a fundamental phenomenon suggested to be related to topics such as genome evolution, synthetic biology, gene expression regulation, intracellular biophysics, and more. However, this phenomenon hasn’t … Continue reading
Date Published: March 12, 2013 Publisher: Public Library of Science Author(s): Roland G. Roberts Abstract: None Partial Text: The ribosome is at the core of cellular life. It’s the incredible machine that trundles along gene transcripts (mRNAs), translating them three letters at a time into the proteins that run most of the workings of the … Continue reading
Date Published: January 3, 2013 Publisher: Public Library of Science Author(s): Céline Jouffe, Gaspard Cretenet, Laura Symul, Eva Martin, Florian Atger, Felix Naef, Frédéric Gachon, Paul E. Hardin Abstract: The authors identify a new role of the circadian clock in coordinating mRNA translation during ribosome biogenesis, a key process for cell metabolism. Partial Text: Circadian … Continue reading
Date Published: July 3, 2013 Publisher: Public Library of Science Author(s): Bruno Pontes, Yareni Ayala, Anna Carolina C. Fonseca, Luciana F. Romão, Racκele F. Amaral, Leonardo T. Salgado, Flavia R. Lima, Marcos Farina, Nathan B. Viana, Vivaldo Moura-Neto, H. Moysés Nussenzveig, Stefan FT. Weiss. http://doi.org/10.1371/journal.pone.0067708 Abstract: Recent studies indicate that the cell membrane, interacting with … Continue reading
Date Published: October 30, 2015 Publisher: Public Library of Science Author(s): Serge Dmitrieff, François Nédélec, Helge Ewers Abstract: Endocytosis is an essential process by which cells internalize a piece of plasma membrane and material from the outside. In cells with turgor, pressure opposes membrane deformations, and increases the amount of force that has to be … Continue reading
Research Article: Cell Membrane Disruption Stimulates NO/PKG Signaling and Potentiates Cell Membrane Repair in Neighboring Cells
Date Published: August 7, 2012 Publisher: Public Library of Science Author(s): Tatsuru Togo, Paul McNeil. http://doi.org/10.1371/journal.pone.0042885 Abstract: Resealing of a disrupted plasma membrane at the micron-diameter range requires Ca2+-regulated exocytosis. Repeated membrane disruptions reseal more quickly than the initial wound, and this potentiation of membrane resealing persists for at least 24 hours after the initial wound. … Continue reading