Proteins
We generally tend to think of proteins only from a dietary lens, as a component of what we eat. However, they are among the most important and abundant organic macromolecules in the human body, with diverse structures and functions. Every cell contains thousands and thousands of proteins, each with specific functions. Some help in the formation of cellular membrane or walls, some help the cell to move, others act as messages or signals and flow seamlessly from one cell to another, carrying information.
Protein Expression
The method by which living organisms synthesize proteins and further modify and regulate them is called protein expression. Protein expression plays a significant role in several types of research and is highly utilized in molecular biology, biochemistry, and protein research laboratories.
What is peripheral proteins?
The plasma membrane (also called cell membrane) is the outermost layer of the cell and regulates the transport of substances into the cell. The plasma membrane allows the entry of some substances (selective substances), hence plasma membrane is called semi-permeable or selectively permeable.
The lipid bilayer structure of plasma membranes allow small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane by simple diffusion. Large polar or ionic molecules like gases, which are hydrophilic cannot easily diffuse through the cell membrane. For this facilitated diffusion process is used, which requires specific transmembrane proteins to bind to the molecule which is to be transported.
The lipid bilayer is a biological membrane consisting of two layers of lipid molecules. Each lipid molecule, or phospholipid, contains a hydrophilic head and a hydrophobic tail. The lipid bilayer functions through the actions of polarity. The inside of the lipid bilayer is nonpolar, while the heads are polar molecules and create hydrogen bonds with other polar molecules. This means that polar molecules like water and ions cannot easily cross through the nonpolar (tail) region of the lipid bilayer. The lipid bilayer contains a number of surface (peripheral) and integral proteins, as well as extracellular and intracellular elements that have specific functions in the cell.
The lipid bilayer is seen in the cellular membrane of most organisms, as well as seen in the nuclear membrane and membrane of various organelle.
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