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An ancient secret of biochemistry: Why are the basic metabolic pathways of all life forms so similar?
In the process of studying living things, we are often surprised by the similarities between different organisms, especially in their metabolic pathways. Metabolism, which is derived from the Greek word for "change," refers to the set of life-sustaining chemical reactions that occur in an organism. These reactions not only provide energy for cellular processes but are also central to the metabolic machinery that builds the foundations of life.
The three main functions of metabolism include converting energy in food into usable energy, converting food into basic building blocks such as proteins and lipids, and eliminating metabolic waste products.
Surprisingly, the basic metabolic pathways of both single-celled bacteria and large multicellular organisms, such as elephants, are remarkably similar. For example, in all known organisms, the carboxylic acid intermediates in the citric acid cycle are nearly identical across species. This not only represents important information in the evolutionary process, but also demonstrates the functional efficiency of these metabolic pathways.
"These similarities may be due to their emergence early in evolutionary history and their retention of potency."
Components of metabolism
The basic structure of living things is mainly composed of four basic molecules: amino acids, carbohydrates, nucleic acids and lipids. These molecules play a crucial role in metabolic reactions.
Amino acids and proteins
Proteins are linear chains of amino acids linked by peptide bonds. Many of these proteins are enzymes that catalyze metabolic reactions, while others have structural or mechanical functions, such as proteins that form the cytoskeleton. In energy metabolism, amino acids can also be used as carbon sources to enter the citric acid cycle.
Lipid
Lipids are the most diverse biochemical group. They mainly play a structural role in biological membranes and can also be used as an energy source. Structural features of lipids include long nonpolar hydrocarbon chains and small polar regions.
Carbohydrates
Carbohydrates are classified into aldehydes and ketones and are the most abundant biomolecules. They play a variety of roles, from storing and transporting energy (such as starch and glycogen) to serving as structural components (such as cellulose in plants).
Nucleotides
Nucleic acids such as DNA and RNA are polymerized from nucleotides and play a key role in the storage and use of genetic information.
Interaction of metabolic processes
Within cells, metabolic processes can be divided into two major systems: dissimilation and synthesis. The purpose of dissimilation is to break down large molecules into small molecules, release energy, and provide raw materials for synthesis. These energy conversions mainly rely on processes such as oxidative phosphorylation.
During energy conversion processes, such as oxidative phosphorylation, electrons removed from organic molecules are transferred to oxygen, and the released energy is used to synthesize ATP.
The connection between genes and metabolism
The similarity of metabolic pathways is not only reflected in the process of chemical reactions, but also in the conservation of genes. Whether it is animals, plants or microorganisms, the genes that control these metabolic pathways have also maintained amazing consistency during evolution.
Furthermore, metabolic disorders play an important role in several diseases, such as type 2 diabetes and cancer. Cancer cells metabolize in very different ways than normal cells, and these characteristics can be targets for therapeutic intervention.
"In-depth research on metabolism not only reveals the basis of life, but may also become the key to understanding and treating many diseases."
The similarity in basic metabolic pathways of different life forms, does this imply that the origin and evolution of life may share common genes and metabolic processes? Or are there hidden mysteries of life that have not been revealed yet among these ancient biochemical secrets?
