Cell MembraneTransport Carroll 1 .docx - Cell Membrane and ... - Free Printable

Problem Analysis:

The image provided is a diagram of the Sodium-Potassium Pump (Na⁺/K⁺-ATPase), which is a crucial protein involved in maintaining the electrochemical gradient across the cell membrane. This pump uses energy from ATP hydrolysis to transport sodium ions (Na⁺) out of the cell and potassium ions (K⁺) into the cell against their concentration gradients.

The task involves identifying various components and processes related to this pump. Let's solve each part step by step.

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Part 1: Labeling Components

#### (a) The structure labeled A is called:
- Answer: Integral Protein
- Explanation: The structure labeled "A" spans the entire lipid bilayer of the cell membrane. Such proteins that are embedded within the membrane are called integral proteins because they are tightly integrated into the phospholipid bilayer.

#### (b) The structure labeled B is called:
- Answer: ATP
- Explanation: The structure labeled "B" is shown as an energy source for the pump. Since the sodium-potassium pump is an active transporter that requires energy, it uses ATP (adenosine triphosphate) as its energy source. ATP is hydrolyzed to ADP (adenosine diphosphate) and phosphate (Pi) to power the transport process.

#### (c) The structure labeled C is called:
- Answer: Phosphorylated Pump
- Explanation: The structure labeled "C" represents the sodium-potassium pump after it has been phosphorylated. Phosphorylation occurs when ATP donates a phosphate group to the pump protein, which changes its conformation and allows it to bind or release ions.

#### (d) The structure labeled D is called:
- Answer: ADP + Pi
- Explanation: After ATP is hydrolyzed to provide energy for the pump, it breaks down into ADP (adenosine diphosphate) and inorganic phosphate (Pi). These are the products of ATP hydrolysis.

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Part 2: Identifying Processes

#### (e) The activity depicted in the diagram is called:
- Answer: Active Transport
- Explanation: The sodium-potassium pump moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients. This requires energy (from ATP), so it is classified as active transport.

#### (f) The mechanism used by the pump is called:
- Answer: Primary Active Transport
- Explanation: Primary active transport directly uses energy from ATP hydrolysis to move substances across the membrane. In contrast, secondary active transport relies on the electrochemical gradient created by primary transporters.

#### (g) The substance being transported out of the cell is:
- Answer: Sodium Ions (Na⁺)
- Explanation: The diagram shows sodium ions (Na⁺) being pumped out of the cell against their concentration gradient.

#### (h) The substance being transported into the cell is:
- Answer: Potassium Ions (K⁺)
- Explanation: The diagram shows potassium ions (K⁺) being pumped into the cell against their concentration gradient.

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Part 3: Function and Importance

#### (i) The function of the sodium-potassium pump is to:
- Answer: Maintain the electrochemical gradient across the cell membrane
- Explanation: The sodium-potassium pump establishes and maintains the unequal distribution of sodium and potassium ions across the cell membrane. This creates an electrochemical gradient, which is essential for various cellular functions, such as generating action potentials in neurons, facilitating nutrient uptake, and regulating osmotic balance.

#### (j) The importance of the sodium-potassium pump is:
- Answer: Critical for cell homeostasis and proper functioning of cells
- Explanation: The sodium-potassium pump is vital for maintaining the resting membrane potential, enabling nerve impulse transmission, and ensuring that cells do not burst due to osmotic imbalances. Without this pump, cells would lose their ability to regulate ion concentrations, leading to cellular dysfunction and death.

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Final Answer:

\[
\boxed{
\begin{array}{ll}
\text{(a)} & \text{Integral Protein} \\
\text{(b)} & \text{ATP} \\
\text{(c)} & \text{Phosphorylated Pump} \\
\text{(d)} & \text{ADP + Pi} \\
\text{(e)} & \text{Active Transport} \\
\text{(f)} & \text{Primary Active Transport} \\
\text{(g)} & \text{Sodium Ions (Na⁺)} \\
\text{(h)} & \text{Potassium Ions (K⁺)} \\
\text{(i)} & \text{Maintain the electrochemical gradient across the cell membrane} \\
\text{(j)} & \text{Critical for cell homeostasis and proper functioning of cells}
\end{array}
}
\]