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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Ribosomal RNA (rRNA) refers to the RNA molecules that are essential structural and functional components of ribosomes, where protein synthesis occurs. Different classes of rRNA molecule are identified by their sedimentation (S) values. E. coli ribosomes contain one 16S rRNA molecule (1541 nucleotides long) in one (small) ribosomal sub-unit, and a 23S rRNA (2904 nucleotides) and a 5S rRNA (120 nucleotides) in the other (large) sub-unit. These three rRNA molecules are synthesized as part of a large precursor molecule, which also contains the sequences of a number of tRNAs. Special processing enzymes cleave this large precursor to generate the functional molecules. Constitutes about 80% of total cellular RNA.
Procaryotic Cells
Published in Maria Csuros, Csaba Csuros, Klara Ver, Microbiological Examination of Water and Wastewater, 2018
Maria Csuros, Csaba Csuros, Klara Ver
Ribosomes are small organelles where protein synthesis occurs and are composed of protein and a type of RNA, called ribosomal RNA. Procaryotic ribosomes differ from eucaryotic ribosomes in the number of proteins and RNA molecules they contain. Procaryotic ribosomes are called 70S ribo-somes, and those of eucaryotic ribosomes are known as 80S ribosomes. The letter S refers to Svedberg unit, which indicates the relative rate of sedimentation during ultra-high-speed centrifugation. Sedimentation rate is a function of the size, weight, and shape of the particles.
Glossary
Published in Maximilian Lackner, Philipp Stadler, Wilhelm Grabow, Handbook of Online and Near-real-time Methods in Microbiology, 2017
Maximilian Lackner, Philipp Stadler, Ida Maylen Øverleir, Jacobo Paredes, Imanol Tubía, Sergio Arana, Gregor Tegl, Ana Carolina Cardoso Marques, Sevcan Aydin
16S ribosomal RNA (or 16S rRNA) is the component of the 30S subunit of a prokaryotic ribosome that binds to the Shine-Dalgarno sequence. The genes coding for it are referred to as 16S rRNA gene and are used in reconstructing phylogenies, due to the slow rates of evolution of this region of the gene (David Elliott and Michael Ladomery 2015)
It's not just about protein turnover: the role of ribosomal biogenesis and satellite cells in the regulation of skeletal muscle hypertrophy
Published in European Journal of Sport Science, 2019
Matthew Stewart Brook, Daniel James Wilkinson, Ken Smith, Philip James Atherton
As ribosomes serve as the protein synthetic machinery of the cell, the rate of protein synthesis is not only determined by translational efficiency (discussed above) but also the total number of ribosomes (translational capacity) (Millward, Garlick, James, Nnanyelugo, & Ryatt, 1973). Ribosomes are themselves composed of RNA (ribosomal RNA (rRNA)), transcribed by RNA polymerase 1 (POL1) as a 47S pre-rRNA which is then cleaved into 28S, 18S, 5.8S and subsequently assembled with ribonuclear proteins to from a mature ribosome (Figure 1) (Chaillou, Kirby, & Mccarthy, 2014). POL1 therefore serves as a primary control point in ribosomal biogenesis, with the transcription factors TIF-1A, TIF-1B and UBF key in forming a PIC with POL1 at the rDNA promoter. The regulation of TIF-1A and UBF transcriptional activity is achieved through multiple signaling proteins, including ERK, AMPK, mTORc1 and P70S6K1 (reviewed in Kusnadi et al., 2015) enabling the control of ribosomal biogenesis to be influenced by multiple pathways such as hormones, nutrients and contractile activity. Another key regulator of ribosomal biogenesis is c-MYC, an oncoprotein involved in regulating cell growth and virtually all aspects of ribosome formation. c-MYC directly upregulates many of the proteins involved in rDNA transcriptional control including UBF, TIF-1A, TIF-1B, Pol1 and many other proteins involved in the formation, processing and export of mature ribosomes. Further, c-MYC enhances POL1 transcription by remodeling rDNA chromatin structure and directly interacting with the SL1 complex, stabilising Pol1 recruitment at the promoter (van Riggelen, Yetil, & Felsher, 2010). Day-to-day fluctuations in MPS that maintain muscle mass in healthy individuals are predominantly achieved by transient increases in translational efficiency, without changes in RNA content (Chesley et al., 1992). RNA content and therefore ribosome number is likely to be adequately maintained to sustain the protein synthetic needs of habitual activity and nutritional intake, whilst being continually replenished to maintain functional ribosomes. In support of this, ribosomal biogenesis pathways are entwined with those regulating translational efficiency (i.e. mTORc1) (Mayer & Grummt, 2006) (Figure 1) and in response to chronic muscle loading or nutritional modulation, bio-markers of increased ribosomal biogenesis are observed (i.e. Increased c-MYC / 47s pre-RNA) (Stec, Mayhew, & Bamman, 2015).