Introduction: Cellular Respiration An electrical energy plant converts energy from one form to another form that can be more easily used .
In the process of photosynthesis, plants and other photosynthetic producers take in energy in the form of light (solar energy) and convert it into chemicalenergy, glucose, which stores this energy in its chemical bonds.
Another chemicalenergy store that results from photosynthesis is oxygen, or O2, which is the necessary component in the air that we breathe.
The form that this energy takes is as molecules called adenosine triphosphate, or ATP: the energy currency of all cells.
Thus, all the chemicalenergy that we obtain from eating (glucose) and breathing (oxygen) is originally derived from solar energy, although we are unable to utilize solar energy ourselves to produce these molecules.
Cellular respiration is the process of transforming chemicalenergy into forms usable by the cell or organism.
In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll; that energy is converted into stored chemicalenergy in the form of NADPH (nicotinamide adenine dinucleotide phosphate) and ATP (adenosine triphosphate).
In the light-independent reactions, the chemicalenergy harvested during the light-dependent reactions drives the assembly of sugar molecules from carbon dioxide.
The energy carriers that move energy from light-dependent reactions to light-independent reactions can be thought of as “full” because they are rich in energy.
After the energy is released, the “empty” energy carriers return to the light-dependent reaction to obtain more energy.
Moreover, the actual step that converts light energy into chemicalenergy takes place in a multiprotein complex called a photosystem, two types of which are found embedded in the thylakoid membrane: photosystem II (PSII) and photosystem I (PSI) .
How Light-Dependent Reactions Work The overall function of light-dependent reactions, the first stage of photosynthesis, is to convert solar energy into chemicalenergy in the form of NADPH and ATP, which are used in light-independent reactions and fuel the assembly of sugar molecules.
Producing ChemicalEnergy Light energy is converted into chemicalenergy in a multiprotein complex called a photosystem.
The two photosystems absorb light energy through proteins containing pigments, such as chlorophyll.
Because the electrons have lost energy prior to their arrival at PSI, they must be re-energized by PSI.
That energy is transmitted to the PSI reaction center.
Light-dependent reactions, which take place in photosystem I and II, convert solar energy into NADPH and ATP.
How Organisms Acquire Energy in a Food Web All living things require energy in one form or another since energy is required by most, complex, metabolic pathways (often in the form of ATP); life itself is an energy-driven process.
It is important to understand how organisms acquire energy and how that energy is passed from one organism to another through food webs and their constituent food chains.
Photoautotrophs harness the solar energy of the sun by converting it to chemicalenergy in the form of ATP (and NADP).
Many chemoautotrophs in hydrothermal vents use hydrogen sulfide (H2S), which is released from the vents, as a source of chemicalenergy.
This allows chemoautotrophs to synthesize complex organic molecules, such as glucose, for their own energy and in turn supplies energy to the rest of the ecosystem.
Autotrophs (producers) synthesize their own energy, creating organic materials that are utilized as fuel by heterotrophs (consumers).
Properties of Life All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing.
Energy Processing All organisms use a source of energy for their metabolic activities.
Some organisms capture energy from the sun and convert it into chemicalenergy in food; others use chemicalenergy in molecules they take in as food .
Key characteristics or functions of living beings are order, stimuli, reproduction, growth/development, regulation, homeostasis, and energy.