Question

the image shows a diagram of the sodium - potassium pump across a cell membrane. there are labels like inside cell, outside cell,sodium - potassium pump, and groups (group 1, group 2, group 3) with different colored boxes. above the diagram, there are sections with ion concentration labels (na⁺ high k⁺ low, na⁺ low k⁺ high) and ion movement notations (3 na⁺ + 2 k⁺, 3 na⁺ 2 k⁺, 2 na⁺ 3 k⁺) along with excess + charge and excess - charge boxes.

Explanation:

Step1: Analyze Sodium-Potassium Pump

The sodium - potassium pump (Na⁺/K⁺ - ATPase) is a crucial membrane protein. Its function is to maintain the electrochemical gradients of sodium and potassium ions across the cell membrane. It actively transports 3 sodium ions (Na⁺) out of the cell and 2 potassium ions (K⁺) into the cell, using ATP as an energy source.

Step2: Determine Ion Concentrations

• For sodium ions (\(Na^+\)): The concentration of \(Na^+\) is high outside the cell and low inside the cell.
• For potassium ions (\(K^+\)): The concentration of \(K^+\) is high inside the cell and low outside the cell.
• Regarding charge: Since 3 \(Na^+\) (positive charge) are pumped out and 2 \(K^+\) (positive charge) are pumped in, there is a net loss of one positive charge from the cell per cycle of the pump. This leads to the inside of the cell having a net negative charge (excess - charge) and the outside having a net positive charge (excess + charge).

Step3: Match Groups to Regions

• Group 1 (pink boxes): These represent the ion concentration regions. The outside of the cell has high \([Na^+]\) and low \([K^+]\), so the Group 1 box on the outside (labeled b) should correspond to \([Na^+]\) high, \([K^+]\) low. The inside of the cell has low \([Na^+]\) and high \([K^+]\), so the Group 1 box on the inside (labeled d) should correspond to \([Na^+]\) low, \([K^+]\) high.
• Group 2 (blue boxes): These represent the charge regions. The outside of the cell has an excess positive charge, so the Group 2 box on the outside (labeled c) should correspond to excess + charge. The inside of the cell has an excess negative charge, so the Group 2 box on the inside (labeled e) should correspond to excess - charge.
• Group 3 (white box on the pump): This is the sodium - potassium pump itself, which is responsible for the active transport of the ions.

Answer:

• For Group 1 (outside, b): \([Na^+]\) high, \([K^+]\) low
• For Group 1 (inside, d): \([Na^+]\) low, \([K^+]\) high
• For Group 2 (outside, c): excess + charge
• For Group 2 (inside, e): excess - charge
• Group 3 (a): Sodium - Potassium Pump (responsible for 3 \(Na^+\) out, 2 \(K^+\) in)