Transmembrane Potential Model #1 K+ Potassium Nat Nat K+ Nat K+ K+ Sodium Gate N

Question

Transmembrane Potential Model #1 K+ Potassium Nat Nat K+ Nat K+ K+ Sodium Gate Nat Nat Na+ K+ Gate K+ Nat K+ Nat Sodium Gate Nat K+ Consider the cell in Model #1 above. Sodium (Na+), potassium (K+), and various negatively charged ions (-) ions are located inside and outside of the cell. Read This: This cell has sodium gates and potassium gates that open and close. When the gates are closed, ions cannot pass through the gates. When a sodium gate is open, it allows only sodium ions to pass through the plasma membrane. When the potassium gate is open, it allows only potassium ions to pass through the plasma membrane. The gates are specific; sodium gates do not allow potassium to pass through them and potassium gates do not allow sodium to pass through them. Neither type of gate allows negatively charged ions to pass through it. Remember that ions will diffuse down their gradients from high concentration to low concentration. This is called diffusion down the chemical gradient. Considering only the chemical gradient for the ions, answer the following questions. 4) When the sodium gate opens, which way will the sodium ions move? Why? 5) When the potassium gate opens, which way will the potassium ions move? Why? 6) When the sodium gate opens, will the potassium ions move? Why or why not?

Explanation / Answer

4.) Sodium ions move out of the cells

Reason

Since sodium is already present inside the cells and Moving out of Na ions from the cell provides the driving force for many active transport membrane proteins which import glucose, amino acids and various other nutrients with the use of the sodium gradient produced

5.) Potassium ions move into the cells

Reason

Potassium is not present inside the cells so import of potassium ions into the cells would create a gradient that would carry out important cellular functions

6.) Yes both sodium and potassium ions move simultaneously.

Three sodium ions are moved out while two potassium ions are imported hence there is a net moving out of a single +charge per pump.

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