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Polymerization, an anabolic pathway used to build macromolecules such as nucleic acids, proteins, and polysaccharides, uses condensation reactions to join monomers. [4] Macromolecules are created from smaller molecules using enzymes and cofactors. Use of ATP to drive the endergonic process of anabolism.
Here, the enzyme aminoacyl-tRNA-synthetase catalyzes two reactions. In the first one, it attaches an AMP molecule (cleaved from ATP) to the amino acid. The second reaction cleaves the aminoacyl-AMP producing the energy to join the amino acid to the tRNA molecule. [14] Ribosomes have two subunits, one large and one small. These subunits surround ...
Metabolism (/ m ə ˈ t æ b ə l ɪ z ə m /, from Greek: μεταβολή metabolē, "change") is the set of life-sustaining chemical reactions in organisms.The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks of proteins, lipids, nucleic acids, and some carbohydrates; and the ...
While the pentose phosphate pathway does involve oxidation of glucose, its primary role is anabolic rather than catabolic. The pathway is especially important in red blood cells (erythrocytes). The reactions of the pathway were elucidated in the early 1950s by Bernard Horecker and co-workers. [2] [3] There are two distinct phases in the pathway.
The first reaction of the cycle, in which oxaloacetate (a four-carbon compound) condenses with acetate (a two-carbon compound) to form citrate (a six-carbon compound) is typically anabolic. The next few reactions, which are intramolecular rearrangements, produce isocitrate .
This molecule acts as a way for the cell to transfer the energy released by catabolism to the energy-requiring reactions that make up anabolism. Catabolism is a destructive metabolism and anabolism is a constructive metabolism. Catabolism, therefore, provides the chemical energy necessary for the maintenance and growth of cells.
The reaction catalyzed is: ATP + AMP ⇔ 2 ADP. The equilibrium constant varies with condition, but it is close to 1. [1] Thus, ΔG o for this reaction is close to zero. In muscle from a variety of species of vertebrates and invertebrates, the concentration of ATP is typically 7-10 times that of ADP, and usually greater than 100 times that of AMP. [2]
Response to stimuli: a response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion; for example, the leaves of a plant turning toward the sun (phototropism), and chemotaxis.