5. Powering a cell

2021 ◽  
pp. 65-75
Author(s):  
Mark Lorch
Keyword(s):  
Carbon Dioxide ◽  
Chemical Reactions ◽  
Metabolic Pathway ◽  
Light Harvesting ◽  
Chemical Energy ◽  
Biochemical Process ◽  
A Cell ◽  
Specific Proteins ◽  
Living Organisms

This chapter looks at some examples of how the groups of major macro- and micromolecules that play a role in biochemistry work in unison, creating interconnected pathways of chemical reactions. The biochemical process that collects the Sun’s rays and uses their energy to convert carbon dioxide and water into carbohydrate is photosynthesis. The most common light harvesting pigments are chlorophylls. Living organisms, including humans, then utilize the stored chemical energy in the carbohydrates, releasing carbon dioxide back into the atmosphere. The chapter then highlights the process of glycolysis, a ten-step metabolic pathway, with each step catalysed by specific proteins.

Green Chemistry: Photosynthesis

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Carbon Dioxide ◽  
Solar Radiation ◽  
Green Chemistry ◽  
Food Chain ◽  
Light Harvesting ◽  
Time Of Day ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
Visible Radiation ◽  
A Cell

Each square metre of the Earth receives up to 1 kW of solar radiation, with the exact intensity depending on latitude, season, time of day, and weather. A significant amount of this energy is harnessed by the almost magical process we know as ‘photosynthesis’ in which water and carbon dioxide are combined to form carbohydrates. Thus, from the air and driven by sunlight, vegetation plucks vegetation. That new vegetation is at the start of the food chain, for its metabolism is used to forge protein and, in our brains, drive imagination. There is probably no more important chemical reaction on Earth. A large proportion of solar radiation is absorbed by the atmosphere. Ozone and oxygen molecules absorb a lot of ultraviolet radiation, and carbon dioxide and water molecules absorb some of the infrared radiation. As a result, plants, algae, and some species of bacteria have to make do with what gets through and evolved apparatus that captures principally visible radiation. The early forms of these organisms stumbled into a way to use the energy of visible radiation, which arrives in the packets we call photons, to extract hydrogen atoms from water molecules and use them and carbon dioxide to build carbohydrate molecules, which include sugars, cellulose, and starch. The oxygen left over from splitting up water for its hydrogen went to waste. Most of the oxygen currently in the atmosphere has been generated and is maintained by photosynthesis since Nature first stumbled on the process about 2 billion years ago and thereby caused the first great pollution. That pollution, in Nature’s characteristically careless and wholly thoughtless and unplanned way, was to turn out to be to our great advantage. Photosynthesis begins in the organelle (a component of a cell) known as a ‘chloroplast’, so you need to poke around inside one if you are to understand what is going on. I shall focus on the light harvesting and the accompanying ‘light reactions’. What follows them, the so called ‘dark reactions’ in which the captured energy is put to use to string CO2 molecules together into carbohydrates, is controlled in a highly complex way by enzymes.

scholarly journals The formation of nitrites from nitrates in aqueous solution by the action of sunlight, and the assimilation of the nitrites by green leaves in sunlight

1918 ◽  
Vol 90 (627) ◽  
pp. 158-167 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Exothermic Reaction ◽  
Structural Type ◽  
Light Energy ◽  
Chemical Energy ◽  
Endothermic Reaction ◽  
Set Up

The number of chemical changes brought about by the activity of light is multitudinous, and the study of these reactions has been very intensive in recent years. In the majority of the photo-chemical reactions, the effect produced is that of hastening an exothermic reaction, and in this resembles the action of a catalyst. The substances formed have a less content of chemical energy than the mother substances, and are usually of a more simple structural type. In such cases there is no clear proof of transformation, or conversion, of light-energy into chemical energy, and the light acts more as a detonator to a chemical reaction in which chemical energy is set free. The most important case of an endothermic reaction set up by the action of light is that in which the synthesis of formaldehyde and carbohydrate is effected in the green leaf, by that action of light upon water and carbon dioxide in which the light-energy is converted into chemical energy and stored up.

Semimetal bismuth mediated UV–vis-IR driven photo-thermocatalysis of Bi4O5I2 for carbon dioxide to chemical energy

2018 ◽  
Vol 23 ◽  
pp. 51-60 ◽  
Author(s):  
Yang Bai ◽  
Ping Yang ◽  
Pingquan Wang ◽  
Haiquan Xie ◽  
Haifeng Dang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Chemical Energy

scholarly journals A transcriptional regulatory circuit for the photosynthetic acclimation of microalgae to carbon dioxide limitation

2020 ◽  
Author(s):  
Olga Blifernez-Klassen ◽  
Hanna Berger ◽  
Birgit Gerlinde Katharina Mittmann ◽  
Viktor Klassen ◽  
Louise Schelletter ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Protein Interactions ◽  
Prolonged Exposure ◽  
Light Harvesting ◽  
Low Carbon ◽  
Protein Protein Interactions ◽  
Regulatory Circuit ◽  
Expression Of Genes ◽  
Transcriptional Regulatory ◽  
Squamosa Promoter Binding Protein

ABSTRACTIn green microalgae, prolonged exposure to inorganic carbon depletion requires long-term acclimation responses, based on a modulated expression of genes and adjusting photosynthetic activity to the prevailing supply of carbon dioxide. Here, we depict a microalgal regulatory cycle, adjusting the light-harvesting capacity at PSII to the prevailing supply of carbon dioxide in Chlamydomonas reinhardtii. It engages a newly identified low carbon dioxide response factor (LCRF), which belongs to the Squamosa promoter binding protein (SBP) family of transcription factors, and the previously characterized cytosolic translation repressor NAB1. LCRF combines a DNA-binding SBP domain with a conserved domain for protein-protein interactions and transcription of the LCRF gene is rapidly induced by carbon dioxide depletion. LCRF activates transcription of the NAB1 gene by specifically binding to tetranucleotide motifs present in its promoter. Accumulation of the NAB1 protein enhances translational repression of its prime target mRNA, encoding the PSII-associated major light-harvesting protein LHCBM6. The resulting reduction of the PSII antenna size helps maintaining a low excitation during the prevailing carbon dioxide limitation. Analyses of low carbon dioxide acclimation in nuclear insertion mutants devoid of a functional LCRF gene confirm the essentiality of this novel transcription factor for the regulatory circuit.

Artificial light-harvesting systems based on macrocycles-assisted supramolecular assembly in aqueous media

2021 ◽  
Author(s):  
Kaiya Wang ◽  
Krishnasamy Velmurugan ◽  
Bin Li ◽  
Xiao-Yu Hu
Keyword(s):  
Light Harvesting ◽  
Aqueous Media ◽  
Supramolecular Assembly ◽  
Routine Activities ◽  
Chemical Energy ◽  
Artificial Light ◽  
Natural Systems ◽  
Harvesting Systems

Light-harvesting, which converts sunlight into chemical energy by natural systems such as plants, bacteria, is one of the most universal routine activities in nature. So far, various artificial light-harvesting systems...

The Magnetic Treatment of Water Solutions and Seeds of Agricultural Crops

2019 ◽  
pp. 256-292 ◽  
Author(s):  
Volodymyr Kozyrskyi ◽  
Mykola Zablodskiy ◽  
Vitaliy Savchenko ◽  
Oleksandr Sinyavsky ◽  
Rauf Yuldashev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Saving ◽  
Chemical Reactions ◽  
Magnetic Induction ◽  
Magnetic Treatment ◽  
Agricultural Crops ◽  
Water Solutions ◽  
Material Resources ◽  
Presowing Treatment ◽  
A Cell

The reclamation of new areas and distant lands with limited energy and material resources demands using resource- and energy-saving technologies. One of such technologies can be magnetic treatment of irrigating water and artificial manure solutions, and presowing treatment of seeds of agricultural crops in magnetic field. The authors found that magnetic field accelerates the velocity of chemical reactions, enhances salts and fertilizers solvability, and increases oxygen concentration in a solution. Magnetic field improves membrane cells permeability which accelerates molecules and ions diffusion through it. This process improves the ability of a seed to absorb water and increases the concentration of oxygen in a cell. Presowing treatment of seeds increases their ability of germination by 26–50%, sprouting by 20–30%. The best regime of water solutions and seeds of agricultural crops treatment in magnetic field is when magnetic induction is 0.065 Tl and the velocity of a solution is 0.4 m/s.

4. The burning issue: molecules and energy

2003 ◽  
pp. 70-93
Author(s):  
Philip Ball
Keyword(s):  
Citric Acid ◽  
Chemical Reactions ◽  
Citric Acid Cycle ◽  
Living Cells ◽  
Metabolic Processes ◽  
Acid Cycle ◽  
Cellular Life ◽  
Metabolic Reactions ◽  
Molecular Reactions ◽  
Living Organisms

‘The burning issue: molecules and energy’ describes how energy can be transferred through molecular reactions. Metabolic processes are the foundation of cellular life. All chemical reactions increase entropy (or disorder), but living cells maintain their order by carefully controlling metabolic reactions. In living organisms glucose is broken down into pyruvate through glycolysis. Pyruvate then enters the citric acid cycle, which is a series of reactions that generate electrons which generate ATP — the cell's ‘fuel’. Many scientists, most notably Alfred Nobel, have sought to develop molecules which contain huge amounts of energy safely. These molecules can be used to build civilization — or destroy life.

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