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Chapter 5: Problem 14

How does the sodium-potassium pump make the interior of the cell negatively charged? a. by expelling anions b. by pulling in anions c. by expelling more cations than it takes in d. By taking in and expelling an equal number of cations.

Short Answer

Expert verified
c. by expelling more cations than it takes in.

Step by step solution

01

- Understanding the Sodium-Potassium Pump

The sodium-potassium pump is a vital cellular mechanism that helps maintain the proper concentration of ions inside and outside of the cell. It actively transports sodium (Na鈦�) and potassium (K鈦�) ions against their concentration gradients using energy from ATP.
02

- Mechanism of the Pump

In each cycle, the sodium-potassium pump moves 3 sodium ions (Na鈦�) out of the cell and 2 potassium ions (K鈦�) into the cell. This process consumes one molecule of ATP.
03

- Net Charge Movement

Since the pump expels 3 cations (positive ions) and only takes in 2 cations, there is a net export of one positive charge per cycle.
04

- Result on Cell's Interior Charge

Due to this net loss of one positive charge per cycle, the interior of the cell becomes negatively charged relative to the outside.
05

- Choosing the Correct Option

Based on the explanation, the correct answer is: c. by expelling more cations than it takes in.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Ion Concentration Gradients
Cells need to maintain different concentrations of ions inside and outside their internal structures to function properly. This difference in ion concentrations is known as ion concentration gradients.

For example, sodium (Na鈦�) ions are more concentrated outside the cell, while potassium (K鈦�) ions are more concentrated inside the cell. These gradients are vital for various cellular processes, including nerve impulse transmission and muscle contraction.

The sodium-potassium pump plays a crucial role in maintaining these ion concentration gradients. By transporting sodium out of the cell and potassium into the cell, it ensures that these concentrations remain balanced, which is essential for the cell鈥檚 overall health and functionality.
ATP Energy Usage
The sodium-potassium pump is an example of active transport, which requires energy to move ions against their concentration gradients. This energy comes from ATP (adenosine triphosphate).

Every time the pump operates, it hydrolyzes one molecule of ATP to ADP (adenosine diphosphate) and an inorganic phosphate, releasing energy. This energy is then used to change the shape of the pump, allowing it to transport 3 sodium ions out of the cell and 2 potassium ions into the cell.

This usage of ATP is crucial because it ensures the pump can continuously operate and maintain the ion gradients, which are necessary for other cellular activities, such as maintaining the cell鈥檚 membrane potential.
Cell Membrane Potential
The cell membrane potential is the voltage difference across the cell's membrane, resulting from the unequal distribution of ions.

The sodium-potassium pump contributes to this membrane potential by moving 3 Na鈦� ions out of the cell for every 2 K鈦� ions it brings in. This results in a net export of one positive charge per cycle, making the inside of the cell more negatively charged compared to the outside.

This negative charge is essential for many cellular functions, especially in neurons where it helps transmit electrical signals. By continually exporting sodium and importing potassium, the sodium-potassium pump ensures that the cell maintains its proper membrane potential, which is crucial for normal cell activity.

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Most popular questions from this chapter

What happens to the membrane of a vesicle after exocytosis? a. It leaves the cell. b. It is disassembled by the cell. c. It fuses with and becomes part of the plasma membrane. d. It is used again in another exocytosis event.

Why must active transport of molecules across plasma membranes function continuously? a. Diffusion cannot occur in certain cells. b. Diffusion is constantly moving solutes in opposite directions. c. Facilitated diffusion works in the same direction as active transport. d. Not all membranes are amphiphilic.

According to the fluid mosaic model of the plasma cell membrane, what is the primary function of carbohydrates attached to the exterior of cell membranes? a. Carbohydrates are in contact with the aqueous fluid both inside and outside the cell. b. Carbohydrates are present only on the interior surface of a membrane. C. Carbohydrates are present only on the exterior surface of a membrane. d. Carbohydrates span only the interior of a membrane.

Arsenic poisoning disrupts ATP production by inhibiting several of the enzymes in the oxidative phosphorylation pathway. Some of the symptoms of arsenic poisoning are similar to cystic fibrosis (difficulty breathing and frequent lung infections). Explain what impact arsenic poisoning may have on components of the plasma membrane and transport that result in CF like symptoms. a. Arsenic poisoning disrupts ATP production, leading to decreased transport of \(\mathrm{Cl}^{-}\) ions by epithelial cells. This leads to decreased electrolyte concentration in the mucus and retention of water into the cells. The mucus becomes dehydrated, as in CF. b. Arsenic poisoning disrupts the \(\mathrm{Na}^{+} / \mathrm{Cl}^{-}\) pump, leading to decreased transport of \(\mathrm{Cl}^{-}\) ions outside the epithelial cells. This increases the electrolyte concentration in the mucus and movement of water out of the cells. The mucus becomes hydrated as in CF. c. Arsenic poisoning affects the oxidative phosphorylation pathway, leading to decreased transport of \(\mathrm{Na}^{+}\) ions outside the epithelial cells. This leads to increased electrolyte concentration in the mucus and movement of water into the cells. The mucus becomes dehydrated as in CF. d. Arsenic poisoning disrupts the binding sites for \(\mathrm{Cl}^{-}\) ions, leading to decreased transport of \(\mathrm{Cl}^{-}\) ions outside the epithelial cells. This leads to decreased electrolyte concentration in the mucus and movement of water outside the cells. The mucus becomes hydrated as in CF.

Describe the process of potocytosis and explain how it differs from pinocytosis. a. Potocytosis is a form of receptor-mediated endocytosis where molecules are transported via caveolae-coated vesicles. Pinocytosis is a form of exocytosis used for excreting excess water. b. Potocytosis is a form of exocytosis where molecules are transported via clathrin-coated vesicles. Pinocytosis is a form of receptor- mediated endocytosis used for excreting excess water. c. Potocytosis is a form of receptor-mediated endocytosis where molecules are transported via caveolae-coated vesicles. Pinocytosis is a mode of endocytosis used for absorption of extracellular water. d. Potocytosis is a form of receptor-mediated endocytosis used for absorption of water. Pinocytosis is a mode of endocytosis used for excretion of extracellular water.
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