Please fill in the blanks and provide a short answer of why you chose your answe
ID: 11286 • Letter: P
Question
Please fill in the blanks and provide a short answer of why you chose your answer
10) Please rank the following substances with respect to their ability to cross a lipid bilayer that lacks
membrane proteins: amino acids, oxygen, water, potassium
Most Permeable 1. ______________________
2. ______________________
3. ______________________
Least Permeable 4. ______________________
11. Assuming a membrane potential of -70mV, what are two reasons why the electrochemical gradient for
Ca++ ([10-7 mM] free in the cytoplasm, [2 mM] outside the cell) is much greater than that of Na+ ([12 mM]
in the cytoplasm, [145 mM] outside the cell)?
a) ________________________________________________________________________________.
b) ________________________________________________________________________________.
Explanation / Answer
10) Please rank the following substances with respect to their ability to cross a lipid bilayer that lacks membrane proteins: amino acids, oxygen, water, potassium water, oxygen, potassium, amino acids why: amino acids ARE proteins, so that would be last; water doesn't mix well with lipids, so it comes first. 11. Assuming a membrane potential of -70mV, what are two reasons why the electrochemical gradient for Ca++ ([10-7 mM] free in the cytoplasm, [2 mM] outside the cell) is much greater than that of Na+ ([12 mM] in the cytoplasm, [145 mM] outside the cell)? With respect to a cell, organelle, or other subcellular compartment, the tendency of an electrically charged solute, such as a potassium ion, to move across the membrane is decided by the difference in its electrochemical potential on either side of the membrane, which arises from three factors: 1. the difference in the concentration of the solute between the two sides of the membrane (Ca++ charge is greater than that of Na+) 2. the charge or "valence" of the solute molecule (Ca++ has one more positive ion, or cation, than Na+) 3. the difference in voltage between the two sides of the membrane (i.e. the transmembrane potential).