Question

Explain why glucose continues to enter a cell, even when the concentration inside the cell might be higher than outside.

How many ions can move through a protein channel per second (on average)?







Do protein channels have specificity? (i.e. Are they specific about what they let cross the membrane or can any molecule go through any channel?)





Explain how the sodium/potassium pump works. Why does this process require ATP?

Answer 1

1)ATP. The concentration of glucose inside of a cell is higher than the concentration outside of that cell, yet glucose continues to enter the cell. ... Two solutions are separated by a selectively permeable membrane that is not permeable to glucose.

2)For transport efficiency, channels have an advantage over carriers in that up to 100 million ions can pass through one open channel each second—a rate 105 times greater than the fastest rate of transport mediated by any known carrier protein.

3)The sodium-potassium pump uses active transport to move molecules from a high concentration to a low concentration. The sodium-potassium pump moves sodium ions out of and potassium ions into the cell. This pump is powered by ATP. For each ATP that is broken down, 3 sodium ions move out and 2 potassium ions move in.