What are the Basics of Bioenergetics?
Bioenergetics:
Bioenergetics is the field of biochemistry and cell biology which deals with the study of the processes by which cells use, store, and release energy. The quantitative study of energy relationships in biological systems is called bioenergetics.
A central component of bioenergetics is energy transformation, the conversion of energy from one form to another. The biological energy transformations obey the laws of thermodynamics. Energy is necessary for growth and reproduction.
We cannot exhibit any of the characteristics of life without a ready supply of energy. In this chapter, we will discuss the most fundamental metabolic processes which are photosynthesis and respiration.
4.1 Photosynthesis
Photosynthesis is the biological process that captures light (solar energy and converts it into chemical energy (i.e. organic molecules, e.g., glucose). It takes place in plants, algae, cyanobacteria, and many bacteria.
Photosynthesis is a "redox" process that links the non-living world to the living world. It involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. The overall reactions of photosynthesis can be as follows.
4.1.1 Role of Light in Photosynthesis:
Light is a form of energy sync Electromagnetic energy or radiation. Solar radiation consists of photons. Photons (Gk. "Phos"-Light) are separate and distinct packets of energy that come from solar radiation. Photons travel in waves, and these waves contain energy. Short waves contain more energy than long waves.
The full range of electromagnetic radiation in the universe is called the electromagnetic spectrum while visible light (380-750 nm) is only a small part of the
spectrum.
Visible light:
Visible light is part of the spectrum that the human eye can see which is white light. Photons of visible light have just the right amount of energy to promote electrons to higher shells on shells in atoms.
Leaves absorb only 1% of the total, that falls on them, rest is reflected or transmitted. The synthesis of ATP from ADP or AMP is called phosphorylation which is endergonic process.
In photosynthetic organisms the energy comes from light thus the process of formation of ATP during photosynthesis is referred to as photophosphorylation. Light falls on green tissues thereby water molecules are broken down (photolysis) into H' ions, OH, radicals, and electrons.
The OH radicals are collected and reassembled as water and molecular oxygen, and both are released into the atmosphere. The Hydrogen ions (protons) are pumped across the thylakoid membrane into the lumen. H ions are used to convert NADP to Nthe ADPH, in the photosystem.
Role of Photosynthetic Pigments:
A photosynthetic pigment is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis. Different pigments absorb light of different wavelengths. Tappearsht appears in different colors when passed through a prism.
Carotenoids:
These are a group of yellow, orange, red,d, or brown pigmeabsorbsorb bluelueu,e, violet,t, and green light. They are associated with the chlorophyll inside the chloroplast or occur alone inside the chloroplast. Carotenoids absorb different wavelengths than chlorophyll, so broaden the spectrum of light that provides energy for photosynthesis.
The chlorophyll b and carotenoids together are called accessory pigments because they absorb light and transfer the energy to chlorophyll a which then starts
reaction.
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