The follow conditions are usually maintained inside a cell under the normal phys
ID: 271066 • Letter: T
Question
The follow conditions are usually maintained inside a cell under the normal physiological conditions at 37 oC: the pH in the cytoplasm is 7.3, the concentrations of Na+ and K+ are 10 mM and 70 mM, respectively; the concentration of phosphate is 25 mM, and the ratio of [ATP]/[ADP] is kept ~ 25; the membrane potential is – 70 mV (more negative inside). Similarly, the pH inside mitochondria is kept at 7.8, and the electrical potential across the inner membrane of the mitochondria is -160 mV (negative inside the matrix).
10. Calculate the osmotic pressure of the cell containing 0.9% NaCl against pure water.(1 pt)
11. What will be the osmotic pressure of the cell containing 0.9% NaCl against seawater which has 3.5% of NaCl by weight? (1 pt)
12. You are asked to make up one liter of isotonic solution for the cell (0.9% salt) using the seawater. How many mL of pure water do you need? (1 pt)
Explanation / Answer
1). 0.9% saline is, 0.9% NaCl solution or 0.9 grams per 100 mL (= 0.1 L)
The molecular weight of NaCl is, 58.44 grams
Osmotic pressure of 0.9% saline is, = 0.9 grams/0.1 L * 1 mol/58.44 grams = 0.154 mol/L