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.
Well, what do you need help with?
Chesapeake bay is an area that has suffered from overharvesting and eutrophication. Eutrophication is an enrichment of water by nutrients salts that causes structural changes in the ecosystem such as increased formation of algae and aquatic plants, depletion of fish species among other effects. The greatest source of nitrogen and phosphorus in a Chesapeake bay is agriculture
Answer:
Explanation:
Normally, under anaerobic condition in yeast, pyruvate produced from glycolysis leads to the production of ethanol as shown below.
pyruvate ⇒ acetaldehyde + NADH ⇒ ethanol + NAD
The pyruvate is converted to acetaldehyde by the enzyme, pyruvate decarboxylase. It should be NOTED that carbon dioxide is released in this step. The acetaldehyde produced in the "first step" is then converted to ethanol by the enzyme alcohol dehydrogenase. It must be noted from the above that the steps are irreversible.
If a mutated strain of yeast is unique because it does not produce alcohol and lactic acid (which is referred to as toxic acid in the question); thus having a high level of pyruvate because of the presence of a novel enzyme. <u>The function of this novel enzyme will most likely be the conversion of acetaldehyde in the presence of carbondioxide back to pyruvate; thus making that step reversible</u>. This could be a possible explanation for the high level of pyruvate present in the yeast.
