The following physiology question contains the correct answer at the bottom. Som
ID: 3473698 • Letter: T
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The following physiology question contains the correct answer at the bottom. Some of the other options were the mechanism of transport was active, simple diffusion, and facilitated diffusion Yet, the answer was the mechanism of transport could not be determined? Why? My professor in my class discussed something about how the beaker contained 1mM and the cell inside (0.8) couldn't be less than that...? l'm not sure I just don't understand why it was none of the above basically. Also, what about if the molecule was charged instead of uncharged? How would that change the answer? Please be detailed in your answer because my exam will contain questions similar to this and I need to understand it! A cell is plaud in a beacer containin C ImM Solution o molec ule p. Molesule p s unchourgec At ime othe concentraction or molecule pinscle the cell . Ar this a to Answer ; the muchanism of transpor cannot be dutkr midExplanation / Answer
The mechanism of transport of molecule p is undetermined because it is an uncharged molecule which is the key to this answer.
see, the transport of the molecule depends upon the charge or polarity of molecule which has to be transferred inside te cell as well as the charge or polarity inside the cell. For example. sodium ions are present at 143 mM outside the cell and 14 mM inside the cell, yet sodium does not freely enter the cell because the positively charged ion cannot pass through the hydrophobic membrane interior. In some circumstances, as during a nerve impulse, sodium ions must enter the cell.
How are they able to do so?
Sodium ions pass through specific channels in the hydrophobic barrier formed by membrane proteins. This means of crossing the membrane is called facilitated diffusion, because the diffusion across the membrane is facilitated by the channel. It is also called passive transport, because the energy driving the ion movement originates from the ion gradient itself, without any contribution by the transport system. Channels, like enzymes, display substrate specificity.
How is the sodium gradient established in the first place?
In this case, sodium must move, or be pumped, against a concentration gradient. Because moving the ion from a low concentration to a higher concentration results in a decrease in entropy, it requires an input of free energy. Protein transporters embedded in the membrane are capable of using an energy source to move the molecule up a concentration gradient. Because an input of energy from another source is required, this means of crossing the membrane is called active transport.
For a charged species, the unequal distribution across the membrane generates an electrical potential that also must be considered because the ions will be repelled by the like charges. The sum of the concentration and electrical terms is called the electrochemical potential.
n this case since the molecule is uncharge so may be with the help of active transport it requires energy to cross the barrier or via simple diffusion or via facilitated diffusion it easily crosses the membrane barrier of the cell and attai that concentration. :) Good luck ;)
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