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Compare the plots of the transport rates for both conditions. What is most likely mechanism of transport for serotonin into these cells? Explain your interpretation.

a. integral memebrane protein that crosses membrane multiple time b. lipid-linked membrane proteins c. peripheral memebrane protein d. integral memebrane protein that crosses membrane ince

Dr Renko studied diffusion of tracer molecules to study paracellular diffusion across an epithelial monolayer of Caco-2 cells.  The tracers were fluorescently labelled dextran molecules of different molecular weight.  She is screening various drugs to determine whether they affect the cells in any way.  Which drugs are most likely to change paracellular diffusion? a.) Drugs that modify microvilli are the most likely to change paracellular diffusion b.) Drugs that modify gap junctions are the most likely to change paracellular diffusion c.) Drugs that modify with aquaporins are the most likely to change paracellular diffusion d.) Drugs that modify tight junctions are the most likely to change paracellular diffusion

A cell creates a H+ gradient across a membrane- in other words, a situation is created were the concentration of H+ is higher on one side then the other of a membrane. How can this H+ concentration gradient be used to do work (that the cells needs to do)?

You design a new matrix to regenerate skin during skin graft. The matrix have cells that need nutrients, such as glucose. You need to figure out the diffusion profile of glucose into the matrix. Assuming glucose has a radius of 1.0nm, you are interested in diffusion from the blood vessels into the matrix, which are 1cm away. The blood viscosity is 3cP, and the glucose concentration in the blood is 4mM. What is the initial flux of glucose? (use 1.38 * 10^-23 J/K for Boltzmann's constant).

The LDL receptor is internalized via endocytosis every ten minutes and recycled to the membrane. How does the cell recycle the receptor and not the ligand (in this case LDL)? A. The high pH (~10) of the early endosome causes dissociation of LDL from the receptor and the receptor is segregated into recycling endosomes. B. The low pH (~5) of the early endosome causes dissociation of LDL from the receptor and the receptor is segregated into recycling endosomes. O C. A targeting sequence on the ligand sorts it to the late endosome/lysosome. D. This is an error-prone process, the ligand often gets recycled accidentally.

b) If you soak an animal cell that is permeable to both water and glucose in either 5.5% glucose or 0.9% NaCl (both isosmotic solutions), the cell exposed to 5.5% glucose will gain water, while the cell exposed to 0.9% NaCl will not gain water. Predict why this is the case.

Even under isotonic conditions, there is a slow leakage of ions into animal cells. How does the plasma-membrane Na+/K+ ATPase enable animal cells to avoid osmotic lysis under isotonic conditions?

Liver cells in culture were kept at 0°C and treated with trypsin to digest the receptors on the cell surface. The temperature was then raised to 37°C and radioactive LDL was added to the culture media. Several hours later, the labeled LDL was found to be inside the cells. This specific process of LDL uptake is A. active transport B. facilitated diffusion C. phagocytosis D. pinocytosis E. receptor-mediated endocytosis