5. Describe endocytosis and exocytosis and explain the difference between the two. Exocytosis is where cells expel materials by vesicles. Vesicles is another way that molecules move in and out of a cell. When the vesicle approaches the cell membrane, a section of the vesicle's membrane fuses with the plasma membrane.
Cell membrane, a semi-permeable structure consists of a lipid bilayer and membrane proteins, which facilitates the transmembrane movement (Campbell et al. 2008). Substances are moving across the hydrophobic region of lipid bilayer using membrane proteins, which regulates the movement of particular substances. Thus, there are two major types of membrane proteins, carrier proteins and channel proteins (Rees et al. 1989).
Second the protein has a complex molecular structure and one should expect protein- protein interactions to be highly directional. Protein self-association can be triggered by chemical transformations; it is also sensitive to physical parameters such as temperature and pressure. Moreover, it is strongly affected by changes in the properties of the medium, such as, pH, the electrolyte concentration, and the presence of co solvents or additives (Stenstan et al.
Microorganisms such as bacteria import nutrient materials that are needed for their growth and survival from the environment as well as exporting metabolites. As the cytoplasm of microbes is separated from the environment by the hydrophobic plasma membrane which is impermeable to hydrophilic solutes, most of the hydrophilic compounds can only pass through the plasma membrane by means of integral membrane proteins which include carrier proteins, permeases or transporters due to the permeability barrier exerted by the phospholipid components of plasma membrane. Movement of solutes in and out of bacteria can be classified by the following processes: diffusion, facilitated diffusion, osmosis, active transport, group translocation, endocytosis and exocytosis. As related to active transport and group translocation, energy is invested in active transport
Platelet-activating factor (PAF) or phospholipid, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine is a phospholipid activator and mediator of leukocyte functions that has many physiological actions. It was discovered and many studies have been done to characterize its messenger functions as a phospholipid.1 PAF is produced by many different cell types such as leukocytes, platelets, mast cells and vascular endothelial cells. PAF amplifies inflammatory responses by promoting leukocyte activation and platelet aggregation.4 PAF is regulated by an enzyme, PAF-acetylhydrolase (PAF-AH), which hydrolyzes PAF rendering it biologically inactive.2 It is important to study PAF regulation by researching the enzymes involved in its degradation to understand
PHYSIOLOGICAL DISTRIBUTION: These lipase enzymes have a widespread biological activity in biological processes from usual metabolism of dietary triglycerides to signalling pathways and inflammatory mechanisms. Thus they are both intracellular and extracellular. 1. Lysosome cell organelle has
It allows the cells to pass through. Then, it also where the process of exchanged between blood and lymphatic vessels occur. Due this process, it allows the lymphatic system to monitor the invading microbes. The lymphatic vessels also carry a clear fluid that it bathes in the body’s tissues that is known as lymph. Another organ is lymph node that is has specialized compartments where the immune system there and can encounter antigens.
Proteins are complex macromolecules that are formed by elements carbon, hydrogen, oxygen and nitrogen. Proteins composed of one or more polypeptide chains of amino acids. The main functions of proteins are to structure, support, protect, make movement, catalyst, transport and make hormones in human body. In the structural role, collagen and elastin provide support for connective tissue. Actin and myosin are proteins that involved in muscle contraction and movement.
Already the name (derived from the Latin word ‘claudere’ meaning ‘close’) explains the function of these molecules: they join endothelial cells together and restrict movement of ions and proteins in-between cells of different tissues. Claudins are 20-34 Kilodalton (kDa) integral membrane proteins of the tight junctions regulating its function (Goncalves et al., 2013). They consist of four-transmembrane domains, N- and C-terminal cytoplasmic domain and two extracellular loops (ECL). The majority is found in epithelial or endothelial cells of all tissues containing tight junctions (Fig. 1 B).
It binds and stabilizes actin filaments, as well as regulating actin-myosin interaction in a calcium (Ca2+)/calmodulin (CaM)- and/or phosphorylation-dependent manner. (17) The domain of this protein includes binding activities to Ca++-calmodulin, actin, tropomyosin, myosin, and phospholipids. As
Carrier proteins do this, acting as pumps that require energy, typically ATP, to function. Some examples include the sodium-potassium pump, exocytosis, and endocytosis. All cells have voltages across their plasma membranes, which is electrical potential energy. The voltage across a membrane is called membrane potential, which is dependent on the charge of the area. Two forces drive the diffusion of ions across a membrane: a chemical force, or in this case, or the ion 's concentration gradient, and an electrical force, or the effect of the membrane potential on an ions movement.