To determine which equation shows how cells use the energy stored in an energy carrier, we need to understand the biochemical processes involved in energy storage and release.
1. Energy Carriers in Cells: Cells use molecules like NADPH, ATP, NADH, and FADH2 as energy carriers. These molecules store energy in chemical bonds, which can be released to perform cellular work.
2. Understanding the Options:
- Option A: [tex]$NADPH \rightarrow NADP^{+} + H^{+}$[/tex]
- NADPH is a reduced form of NADP+ carrying high-energy electrons.
- The conversion of NADPH to NADP+ and H+ involves the release of energy as it loses electrons.
- This process is critical in cellular respiration and photosynthesis where the energy is used for various cellular processes.
- Option B: [tex]$ATP - ADP + NADPH$[/tex]
- This is not a valid equation as it doesn't properly represent a biochemical reaction.
- The ATP and ADP relationship involves phosphorylation, but it does not directly link with NADPH this way.
- Option C: [tex]$NADP^{+} + P - ATP$[/tex]
- This is also not a valid equation.
- It suggests the formation of ATP from NADP+ and P, which is incorrect.
- Option D: [tex]$ADP + H^{+} - ATP$[/tex]
- This equation does not correctly represent a biochemical reaction.
- It implies a relationship that is not reflective of how energy carriers function.
3. Analysis of the Correct Option:
- The correct equation must properly show how an energy carrier releases its stored energy.
- Option A simply and correctly shows the conversion of NADPH to NADP+ and H+, which involves the release of energy stored in NADPH.
Thus, the equation that shows how cells use the energy stored in an energy carrier is:
A. [tex]$NADPH \rightarrow NADP^{+} + H^{+}$[/tex]
This reaction illustrates the release of energy from NADPH, which is used in various cellular processes.
