The cell membrane is an extremely pliable structure composed primarily of back-to-back phospholipids (a “bilayer”). Cholesterol is also present, which contributes to the fluidity of the membrane, and there are various proteins embedded within the membrane that have a variety of functions.
A single phospholipid molecule has a phosphate group on one end, called the “head,” and two side-by-side chains of fatty acids that make up the lipid tails (Figure 1). The phosphate group is negatively charged, making the head polar and hydrophilic—or “water loving.” A hydrophilicmolecule (or region of a molecule) is one that is attracted to water. The phosphate heads are thus attracted to the water molecules of both the extracellular and intracellular environments. The lipid tails, on the other hand, are uncharged, or nonpolar, and are hydrophobic—or “water fearing.” A hydrophobic molecule (or region of a molecule) repels and is repelled by water. Some lipid tails consist of saturated fatty acids and some contain unsaturated fatty acids. This combination adds to the fluidity of the tails that are constantly in motion. Phospholipids are thus amphipathic molecules. An amphipathic molecule is one that contains both a hydrophilic and a hydrophobic region. In fact, soap works to remove oil and grease stains because it has amphipathic properties. The hydrophilic portion can dissolve in water while the hydrophobic portion can trap grease in micelles that then can be washed away.
Cynndi made a fruit salad using her grandmothers recipe. Cynndi has to read the recipe to learn how to make it and also would have to learn how to prepare the fruit.
Answer:
Release or egress
Explanation:
Virus can reproduce only within a host cell, this cycle of infection begins with the <em>attachment</em>, where the virus attaches to a specific receptor site on the host cell, after this comes the<em> entry,</em> in the case of enveloped virus, the envelope can fuse directly with the cell membrane to enter the cell, they can also enter through endocytosis. After entering the cell the virus initiates a <em>replication and assembly </em>mechanism depending on its genome, finally, the last stage of viral replication is the <em>release or egress </em>of the new virions produced in the host organism, some viruses can be released when the host cell dies, but some can leave infected cells by budding through the membrane without directly killing the cell.
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Answer:
Simple organisms, such as theamoeba and earthworm, have a moist, permeable external surface. Oxygencan pass into them through this surface by diffusion. A large surface area is needed for effective gas exchange - so larger, more complex, organisms have special organs such as gills and lungs.
Explanation:
Winds will blow eat to west
