One way is cars and another is factories
Answer:
<h2>C. placing carrier proteins in the membrane.</h2>
Explanation:
If there is no barrier preventing molecules from moving molecules, then there will be large movement of molecules from an area of high concentration to an area of low concentration. This passive process is known as diffusion. The phospholipid bilayer of a cell's membrane works as a barrier to large molecules, ions, and most hydrophilic molecules. Whereas small hydrophobic molecules can pass freely through the phospholipid bilayer, other molecules and ions are transported across the cell membrane with the help of transport proteins. Some transport proteins, allowing hydrophilic molecules and ions to passively move through them and across the cell membrane.
Examples: carrier proteins and channel proteins.
Placing carrier proteins in the cell membrane will allow the molecule to reach equal concentrations on the both the sides of the membrane and maintain that way over long time. In contrast, transport proteins known as pumps will use cellular energy, usually in the form of ATP, to transport molecules.
Placing equal numbers of intracellularly directed and extracellularly directed pumps would also equalize the concentrations of a molecule long over time. Pumps are to transport molecules against their concentration gradient, such as the sodium-potassium pump continuously moves sodium ions out of a cell.
Through the use of carrier proteins, there is equalization of concentrations of a hydrophilic molecule. This equalize the numbers of molecules on the inside and outside of the cell, but the pumps would continue moving the molecule inward, eventually resulting in more molecules inside of the cell than out.
Answer:
C) They live in moist environments and have xylem.
Answer:
Here, we have a composition passage and we are required to fill in the with missing words. The missing words are highlighted in bold format and underlined.
Lecithins and cephalins are both <u>glycerophospholipids;</u> they consist of <u>glycerol</u> with fatty acids forming <u>ester</u> bonds with the first and second <u>hydroxyl </u>groups. The third <u>hydroxyl</u> group of the <u>glycerol </u>forms a<u> phosphate bond </u>with phosphoric acid, which forms another<u> phosphate </u>bond with an amino alcohol. In lecithins, the amino alcohol is <u>choline;</u> in cephalins, the amino alcohol is usually <u>ethanolamine. </u>
Explanation:
Lecithin is a chemical complex composed primarily of fatty acids, glycerol, phosphoric acid, and choline. It can be present in egg yolks, soybeans, sunflower seeds, and plant seed cells and is completely normal. Soybean and sunflower lecithins contain much more important fatty acids than rapeseed lecithin, making them nutritionally more useful.
Phosphatidylethanolamine, also known as cephalin, is a phosphoglyceride that, like phosphatidylcholines and lecithins, is a component of biological membranes. A glycerol residue esterified by two fatty acids and a phosphoethanolamine residue gives rise to phosphatidylethanolamines. They're made by combining CDP-ethanolamine with diglycerides and releasing a CMP molecule. Phosphatidylcholines are formed when S-adenosylmethionine methylates the amine in ethanolamines. They're mostly found in the inner layer of plasma membranes' lipid bilayers.
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Answer:
paracrine signaling.
Explanation:
Chemical signaling between cells is one of the most important ways that activities of tissues and organs are coordinated. The nervous system is the other major coordinating system in animals, but even here chemical signaling is used between adjacent neurons. The mechanisms involved are described as either being paracrine, autocrine, intracrine, endocrine, neuroendocrine or pheromones. Paracrine signals diffuse locally and act on neighboring cells.