Answer:
An ATOM!, is the smallest unit of matter that has characteristic properties of its element. Explanation: An atom a major part of the matter. (Everything in the world (except energy) is made of a material, and, so, everything in the universe is composed of atoms.
Answer:
Why are molecules such as valinomycin effective at transporting ions across the membrane?
Valinomycin is effective as transporting ions across the membrane because it is no charged, so it can carry ions.
Why would a drop in temperature to or below the transition temperature limit valinomycin mediated K+ transport across the plasma membrane?
Valinomycin is limited by temperature because its activity is highly sensitive and it depends on a stable and an average temperature.
Explanation:
Valinomycin is effective at transporting ion across the membrane because is an antibiotic that alternates hydroxy and amino acid, ans it helps membranes to be permeable. Valinomycin is a cyclic molecule that helps in ions transportation through membranes. Also, antibiotics have a temperature range of activity, that's why it is sensitive to changes.
Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
