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Cellular and Molecular Basis of Human Biology
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
In order to function as an inclusive unit, cell has to be self-contained, so to speak. To accomplish this role, the human cells have a cell membrane to govern what goes in and what comes out, sort of like a gate-keeper for the cell. Figure 1 illustrates a schematic diagram of a typical cell membrane. Composed primarily with phospholipid bilayers, the cell membrane arranged its hydrophilic heads facing the aqueous environments inside and outside the cell, with hydrophobic tails facing inside of the cell membrane. Since the middle of cell membrane is hydrophobic, water and proteins, both are hydrophilic in nature, cannot pass through and can only through the cell membrane by way of protein channel. The outer surface of cell membrane also has carbohydrate, glycoprotein, and glycolipid embedded, some of them serve as cell receptors. These cell receptors are particularly important for immune cells, as they need the receptors to recognize danger and to activate immune response against enemies, real or perceived. We should see one essential example in the interaction between T cell and antigen presenting cells in dendritic cell section below (Fig. 2). In a later chapter of this book, the students will learn more details on the importance of cell surface receptors. In the chapter of Precision, we will illustrate how investigators are finding ways to modify T cell surface receptors to trigger immune response to kill cancer cells (Chapter 12).
Biological Responses in Context
Published in Arthur T. Johnson, Biology for Engineers, 2019
Physical intimacy (touch) is important also at the cellular level. The cell membrane has many receptors, each with a specific function. Many of these provide the means for substances to be transferred into or out of the cell; the cell membrane is otherwise nearly impervious to transmembrane movement of larger ions or compounds. These receptors can also act as portals through which viruses access the cell interior. The Transferrin Receptor 1, for instance, which usually brings the element iron into the cell, can also act as access for the deadly Machupo virus to enter the cell (Vastag, 2010).
Endogenous Bioelectric Phenomena and Interfaces for Exogenous Effects
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
The cell membrane surrounds the cytoplasm of the cell and separates intracellular components from the extracellular environment—like a skin. The arrangement of hydrophilic heads and hydrophobic tails of the lipid bilayer can halt polar solutes (e.g., amino acids, nucleic acids, carbohydrates, proteins, and ions) from diffusing across the membrane, but generally allows for the passive diffusion of hydrophobic molecules. This enables the cell to control the movement of these substances via pores and gates (all composed mainly of proteins) for the ion transport—rendering a selective permeability.
Toxicological and pharmacokinetic properties of sucralose-6-acetate and its parent sucralose: in vitro screening assays
Published in Journal of Toxicology and Environmental Health, Part B, 2023
Susan S. Schiffman, Elizabeth H. Scholl, Terrence S. Furey, H. Troy Nagle
Within the current study, results of the sucralose vs sucralose-6-acetate comparison of gene expression are consistent with the sucralose-6-acetate vs control comparison that indicate sucralose-6-acetate impaired normal cellular functioning. The expression of genes for essential and fundamental cellular functions were lower in sucralose-6-acetate relative to sucralose. The Farnesyl-diphosphate farnesyltransferase (FDFT1) gene that encodes the first specific enzyme in cholesterol biosynthesis was markedly expressed by sucralose relative to sucralose-6-acetate with a fold change of 30.93. Cholesterol is not only essential for stability of cell membranes but also for tight junction formation (Shigetomi et al. 2023). Taken together data obtained from the sucralose vs sucralose-6-acetate comparison along with increased expression of MT1G, SHMT2, ATF3, and CHST3 in the sucralose-6-acetate vs control comparison indicated that exposure of human intestinal epithelium to sucralose-6-acetate disrupts essential cellular processes.
Exogenous melatonin improves cadmium tolerance in Solanum nigrum L. without affecting its remediation potential
Published in International Journal of Phytoremediation, 2022
Yue Teng, Wenjie Guan, An Yu, Zhishuai Li, Zhenjun Wang, Hongyan Yu, Luyi Zou
The cell membrane is a selectively permeable membrane, its main function is to regulate and control the transportation and exchange of substances inside and outside the cell (Gill et al.2015a). Numerous reports have shown that exposure to Cd could lead to oxidative damage on plants by inducing elevated production of the outburst of ROS (Hasanuzzaman et al.2017b). Next, overgeneration of ROS acts on the cell membrane composed mainly of lipids and proteins, destroying the structure and function of the membrane, further causing toxic effects on plant cells, and consequently leading to membrane lipid peroxidation and loss of membrane integrity (Sharma et al.2012). In plants, the MDA content and REL are indicators of lipid peroxidation and cell membrane permeability, respectively, and are useful indexes for stress levels (Gill et al.2015a). In the present study, the leaves of S. nigrum under Cd stress showed elevated MDA content and REL (Figures 2A,B) compared with the control seedlings. The above experiment results indicated that excessive lipid peroxidation and loss of membrane integrity occurred under severe Cd stress (50 μM) due to the accumulation of metals and ROS (Soares et al.2016). Similar results were also shown in earlier studies on Cd stress (Hasanuzzaman et al.2017a; Ogunkunle et al.2020; Guo et al.2021).
The response of three typical freshwater algae to acute acid stress in water
Published in Journal of Environmental Science and Health, Part A, 2022
Xing Ma, Xuan Chen, Jiangtao Fan, Yunzhong Wang, Jianfeng Zhang
The cell membrane is the first barrier between the external environment and the intracellular medium and plays an important role in cellular growth, metabolism, energy transduction, and maintenance of a constant intracellular environment.[37] Moreover, the cell membrane regulates the movement of substances entering or exiting the cell and catalyzes exchange reactions.[38] Maintaining the integrity of the cell membrane is necessary for the normal growth of algal cells. Similar to the response of algae to salinity stress, the osmotic pressure inside and outside algal cells also increases with the concentration of hydrogen ions in the culture medium. As a result, the death of algae under acid stress could be attributed to the structural destruction of the cell membrane caused by excessive osmotic pressure and the attack of ROS induced by excess H ions entering the cell membrane. This observation was confirmed by the entry of PI dye into cells with damaged membranes and the staining of nucleic acid substances.