Active Transport - Biology

1. Fundamental Concepts

Definition: Active transport is a cellular process that moves molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration, requiring energy input.
Energy Source: The energy for active transport is often provided by the hydrolysis of adenosine triphosphate (ATP).
Carrier Proteins: Specialized proteins in the cell membrane facilitate the movement of substances against their concentration gradient.

Basic Rule: $${\text{{Active transport requires energy}}}$$

Degree Preservation: The direction of movement is opposite to the natural diffusion gradient

Application: Used in various biological processes such as nutrient uptake and waste removal

Problem: Explain how sodium-potassium pumps work.

The sodium-potassium pump uses ATP to move three sodium ions ($$\text{{Na}}^+$$) out of the cell and two potassium ions ($$\text{{K}}^+$$) into the cell.
This process maintains a higher concentration of sodium ions outside the cell and a higher concentration of potassium ions inside the cell.

Validation: This mechanism helps maintain the resting potential of neurons and muscle cells.

Problem: Calculate the net movement of ions through a sodium-potassium pump if it operates 100 times per second.

Each cycle of the pump moves 3 $$\text{{Na}}^+$$ ions out and 2 $$\text{{K}}^+$$ ions in.
Total $$\text{{Na}}^+$$ ions moved out per second = 3 ions/cycle × 100 cycles/second = 300 ions/second.
Total $$\text{{K}}^+$$ ions moved in per second = 2 ions/cycle × 100 cycles/second = 200 ions/second.

Validation: Net movement of ions per second = 300 $$\text{{Na}}^+$$ ions out - 200 $$\text{{K}}^+$$ ions in = 100 ions out.

Visual Strategy: Use diagrams to illustrate the movement of ions across the cell membrane.
Error-Proofing: Double-check the stoichiometry of ion movements during each cycle of the pump.
Concept Reinforcement: Relate active transport mechanisms to real-world examples like the function of kidneys in filtering blood.