Question

credit (right) image created by cogent learning using pdb entry 2zxe. shinoda, ogawa et al. (2009) crystal structure of the sodium - potassium pump at 2.4a resolution doi.org/10.2210/pdb2zxe/pdb
to interpret the cartoon, note that the artist is drawing the same protein four times, to illustrate how it changes through one pumping cycle. second, notice that the protein has two shapes: one that presents a binding site for sodium to the interior of the cell, and one that presents a binding site for potassium to the exterior of the cell. third, focus on what is going on with atp. when a phosphate group from atp binds to the pump, it switches position. that makes sense—a phosphate ion carries four full negative charges, so it delivers a jolt of electric charge when it binds. later, when the phosphate group falls off, the protein switches back to its original conformation. finally, note that the artist drew little dimples inside the pump. these are meant to represent the binding sites for the sodium and potassium ions.
based on these models you just analyzed and the text description of the sodium - potassium pump, indicate which of the following statements are correct or represent logical predictions.
as the pump continues to work, sodium concentrations will decrease outside the cell and potassium concentrations will decrease inside the cell.
the binding sites for sodium and potassium ions are defined by r - groups with specific sizes, shapes, and charges or partial charges.
the “transmembrane” portion of the pump, which interacts directly with the hydrophobic tails of phospholipids, consists primarily of beta - pleated sheets.
“cartoon” models of molecules or machines can be useful in illustrating how biological processes work.
like charges repel and unlike charges attract, so adding or removing 4 full negative charges to one spot on the pump will affect other charged groups in the molecule.
did you fully understand the concept covered in this

Explanation:

1. The sodium - potassium pump actively transports sodium out of the cell and potassium into the cell, so sodium concentrations increase outside and potassium concentrations increase inside, making the first statement incorrect.
2. The binding sites for ions on proteins are defined by the properties of R - groups such as size, shape, and charge, so the second statement is correct.
3. The transmembrane portion of membrane - spanning proteins like the sodium - potassium pump typically consists mainly of alpha - helices, not beta - pleated sheets, so the third statement is incorrect.
4. Cartoon models are indeed useful for visualizing and understanding biological processes, so the fourth statement is correct.
5. Charged groups in a molecule interact according to the principle of like charges repelling and unlike charges attracting, so adding or removing a charged group can affect other charged groups, making the fifth statement correct.

Answer:

B. The binding sites for sodium and potassium ions are defined by R - groups with specific sizes, shapes, and charges or partial charges.
D. "Cartoon" models of molecules or machines can be useful in illustrating how biological processes work.
E. Like charges repel and unlike charges attract, so adding or removing 4 full negative charges to one spot on the pump will affect other charged groups in the molecule.