Question

For a neuron to function, an input of free energy from ATP is required to set up the sodium and potassium ion concentration gradients such that a signal can be propagated down the axon of a neuron without the necessity of ATP. The system could have worked the opposite way. The neuron could have used ATP to move ions across when a signal was being propagated and then allow natural diffusion to return the ions to their respective sides of the membrane. What advantage does the organism have using ATP up front

Answer 1

Using ATP to maintain the ionic gradients in neurons allows for rapid signal transmission, ensuring neurons are always ready to fire. This readiness permits swift responses and efficient functioning of the nervous system, critical for an organism’s survival.

Step-by-step explanation:

The advantage of using ATP up front in neurons is largely due to the efficiency and readiness required for rapid signal transmission. For a neuron to propagate a signal, or an action potential, a specific ionic balance must be maintained: there must be higher concentrations of sodium ions outside of the cell and potassium ions inside. This gradient is established by the sodium-potassium pump, which actively transports Na+ out of the neuron and K+ into the neuron against their concentration gradients, using ATP.

During an action potential, ion channels open allowing Na+ and K+ to move down their gradients, which creates the electrical impulse. This initial investment of energy ensures that the neuron can respond rapidly to a stimulus without delay, which is critical for the quick reflexes and fast signal transmission needed for tasks such as muscle coordination and sensory perception. Moreover, only a small fraction of these ions move during each action potential, allowing the neuron to fire many times before it must utilize more ATP to restore the ion balance. The active use of ATP for maintaining the resting potential enables the rapid onset of action potentials and thereby a rapid response to stimuli, which is advantageous for organism survival.

Answer 2

The lack of ATP would slow nerve responses to generate an action potential

Step-by-step explanation:

Adenosine triphosphate (ATP) is the main source of energy in the cells. Moreover, ATPases are pumps that use ATP in order to transport sodium and potassium ions across the cell membrane and thus create an action potential. In stressful situations (e.g., escape from a predator) the lack of ATP would not allow to develop fast nerve responses, thereby ATP is required during rest periods and the flow of ions is used when is required a fast response.