Exam 12: Transport Across Cell Membranes

The Na⁺-K⁺ ATPase is also known as the Na⁺-K⁺ pump.It is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration.What happens immediately after the pump hydrolyzes ATP?

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell.Which of the following negatively charged ions is NOT primarily used to buffer positive charges inside the cell?

The toxicity of mercury depends greatly upon the formulation of the metal.Which of them (elemental, metal ion, or methyl-mercury) is more likely to be absorbed through the skin? Explain your answer.

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below.Not all words or phrases will be used; each word or phrase should be used only once. active hydrophilic noncovalent amino acid hydrophobic passive amphipathic ion channels transporter proteins A molecule moves down its concentration gradient by __________ transport, but requires __________ transport to move up its concentration gradient.Transporter proteins and ion channels function in membrane transport by providing a __________ pathway through the membrane for specific polar solutes or inorganic ions.__________ are highly selective in the solutes they transport, binding the solute at a specific site and changing conformation so as to transport the solute across the membrane.On the other hand, __________ discriminate between solutes mainly on the basis of size and electrical charge.

Describe the process by which gut epithelial cells use transporters to take up ingested glucose (against the concentration gradient) and to distribute glucose to other tissues by moving it back out of the cell (down the concentration gradient).

Below is a list of molecules with different chemical characteristics.Knowing that all molecules will eventually diffuse across a phospholipid bilayer, select the option below that most accurately predicts the relative rates of diffusion of these molecules (fastest to slowest). Alanine estrogen propanol sodium