Question

The movement of material(s) across membranes is arguably the most critical function within a cell. Please DESCRIBE three examples of the “movement of material” through a membrane. Why is it important? Each example should be a 3-5 sentence description.

Answer 1

Okay, let us take this 3 examples:

1.- Proton pumping in mitochondria: This is a pump mechanism, protons cannot simply pass through the membrane by themselves, they require special complexes and electrically negative energy to pump them into the inter membrane space. This process is extremely important since this increasing gradient of protons is then used to produce ATP, that is because they can only return to the matrix down their gradient by passing through the ATPsynthase

2.- Glucose facilitated diffusion: Glucose is just too big and not hydrophobic to just diffuse across the cell membrane. To solve this the membrane has specific channels that recognize glucose in the outside and bind to it, this binding changes the configuration of the channel and then opens to allow the entrance of the attached glucose. Since this does not uses energy it requires higher glucose concentrations in the outside to occur. This process is crucial for the cells energy obtention.

3.- Sodium potassium pump: This process requires the molecules to cross the membrane against concentrations gradients and quite quickly, energy is spent in the form of ATP to bring 2 K+ into the cell and 3 Na+ outside the cell. This process is crucial for neuron action potential to occur, so nervous signaling requires it.