![]() What is the definition of zooplankton? 3 answers Zooplankton are small animals that drift in the water and feed on small floating plants. Overall, cyanobacteria are important microorganisms with diverse metabolic capabilities and potential applications in various fields. They have the potential to be used as photosynthetic workhorses for large-scale industrial applications, but further research and engineering are needed to improve their production yields and efficiency. Cyanobacteria are known for their ability to produce bioactive compounds, some of which have shown anticancer activity. They also have the potential for a hydrogen-based lithoautotrophic metabolism. Cyanobacteria possess intersecting photosynthetic and respiratory electron transport chains, which allow them to adjust electron flow and energy metabolism as needed. They are photosynthetic microorganisms that can utilize sunlight directly to convert carbon dioxide or even nitrogen into a variety of industrially relevant chemicals. The kinase and the phosphatase are also regulated.Cyanobacteria are ecologically versatile microorganisms that can be found in various environments, ranging from marine systems to arid deserts. Pyruvate dehydrogenase is also regulated by phosphorylation: A kinase phosphorylates it to form an inactive enzyme, and a phosphatase reactivates it. If either acetyl groups or NADH accumulate, there is less need for the reaction and the rate decreases. ![]() If more energy is needed, more pyruvate will be converted into acetyl CoA through the action of pyruvate dehydrogenase. Pyruvate kinase is also regulated by ATP (a negative allosteric effect). Dephosphorylation by a phosphatase reactivates it. (Recall that fructose-1,6-bisphosphate is an intermediate in the first half of glycolysis.) The regulation of pyruvate kinase involves phosphorylation by a kinase (pyruvate kinase kinase), resulting in a less-active enzyme. The enzyme’s activity is increased when fructose-1,6-bisphosphate levels increase. If no more energy is needed and alanine is in adequate supply, the enzyme is inhibited. The pyruvate produced can proceed to be catabolized or converted into the amino acid alanine. The last step in glycolysis is catalyzed by pyruvate kinase. Fermentation, with its production of organic acids like lactic acid, frequently accounts for the increased acidity in a cell however, the products of fermentation do not typically accumulate in cells. An increase in citrate concentration can occur because of a blockage in the citric acid cycle. ![]() High levels of ATP, citrate, or a lower, more acidic pH decrease the enzyme’s activity. Phosphofructokinase is the main enzyme controlled in glycolysis. Note that the first two steps that are regulated occur early in the pathway and involve hydrolysis of ATP. The glycolysis pathway is primarily regulated at the three key enzymatic steps (1, 2, and 7) as indicated. Once the overall concentration of the chemical decreases, it will diffuse away from the protein, and the control is relaxed. This feedback type of control is effective as long as the chemical affecting it is attached to the enzyme. This binding can increase or decrease the enzyme’s activity, providing feedback. ![]() This alteration of the protein’s (the enzyme’s) structure either increases or decreases its affinity for its substrate, with the effect of increasing or decreasing the rate of the reaction. The allosteric effector alters the steric structure of the enzyme, usually affecting the configuration of the active site. These regulators, allosteric effectors, may increase or decrease enzyme activity, depending on the prevailing conditions. The molecules most commonly used in this capacity are the nucleotides ATP, ADP, AMP, NAD +, and NADH. In contrast, if two different enzymes (each specific for a given direction) are necessary for a reversible reaction, the opportunity to control the rate of the reaction increases, and equilibrium is not reached.Ī number of enzymes involved in each of the pathways-in particular, the enzyme catalyzing the first committed reaction of the pathway-are controlled by attachment of a molecule to an allosteric site on the protein. Reactions that are catalyzed by only one enzyme can go to equilibrium, stalling the reaction. Some reactions are controlled by having two different enzymes-one each for the two directions of a reversible reaction. A cascade of events that occurs upon insulin binding to a receptor in the plasma membrane causes GLUT4-containing vesicles to fuse with the plasma membrane so that glucose may be transported into the cell. GLUT4 is a glucose transporter that is stored in vesicles.
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