Prosthetic groups are organic or inorganic, non-peptide molecules bound to a protein that facilitate its function prosthetic groups include co-enzymes, which are the prosthetic groups of enzymes. A prosthetic group is a non-protein molecule required for the activity of a protein. FMN, which is derived from vitamin B 2, also called riboflavin, is one of several prosthetic groups or co-factors in the electron transport chain. This complex, labeled I, is composed of flavin mononucleotide (FMN) and an iron-sulfur (Fe-S)-containing protein. To start, two electrons are carried to the first complex aboard NADH. In the process, protons are pumped from the mitochondrial matrix to the intermembrane space, and oxygen is reduced to form water. The current of hydrogen ions powers the catalytic action of ATP synthase, which phosphorylates ADP, producing ATP.įigure 7.11 The electron transport chain is a series of electron transporters embedded in the inner mitochondrial membrane that shuttles electrons from NADH and FADH 2 to molecular oxygen. Therefore, a concentration gradient forms in which hydrogen ions diffuse out of the matrix space by passing through ATP synthase. This causes hydrogen ions to accumulate within the matrix space. Rather, it is derived from a process that begins with moving electrons through a series of electron transporters that undergo redox reactions. Most of the ATP generated during the aerobic catabolism of glucose, however, is not generated directly from these pathways. You have just read about two pathways of glucose catabolism that generate ATP-glycolysis and the citric acid cycle. These questions address the following standards: The Science Practices Assessment Ancillary contains additional test questions for this section that will help you prepare for the AP ® exam. Growth, reproduction, and maintenance of living systems require free energy and matter.Ģ.A.1 All living systems require constant input of free energy.ġ.4 The student can use representations and models to analyze situations or solve problems qualitatively and quantitatively.ģ.1 The student can pose scientific questions.Ģ.4 The student is able to use representations to pose scientific questions about what mechanisms and structural features allow organisms to capture, store, and use free energy.Ħ.2 The student can construct explanations of phenomena based on evidence produced through scientific practices.Ģ.5 The student is able to construct explanations of the mechanisms and structural features of cells that allow organisms to capture, store, or use free energy. Big Idea 2īiological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis. A Learning Objective merges required content with one or more of the seven Science Practices. As shown in the table, concepts covered in this section also align to the Learning Objectives listed in the Curriculum Framework that provide a transparent foundation for the AP ® Biology course, an inquiry-based laboratory experience, instructional activities, and AP ® exam questions. Information presented and the examples highlighted in the section support concepts outlined in Big Idea 2 of the AP ® Biology Curriculum Framework, as shown in the table. Under aerobic conditions, the stages of cellular respiration can generate 36–38 ATP. As the protons are driven down their concentration gradient through ATP synthase, ATP is generated from ADP and inorganic phosphate. This process contributes to the formation of the H + gradient used in chemiosmosis. The electrons pass through a series of redox reactions, using free energy at three points to transport hydrogen ions across the membrane. Electrons carried by NADH and FADH 2 are delivered to electron acceptor proteins embedded in the membrane as they move toward the final electron acceptor, O 2, forming water. The ETC is located in membrane of the mitochondrial cristae, an area with many folds that increases the surface area available for chemical reactions. The electron transport chain (ETC) is the stage of aerobic respiration that uses free oxygen as the final electron acceptor of the electrons removed during glucose metabolism in glycolysis and the citric acid cycle.
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