How to Make ATP - membranes) that contains numerous...

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How to Make ATP Two processes convert ADP into ATP: 1) substrate-level phosphorylation; and 2) chemiosmosis . Substrate-level phosphorylation occurs in the cytoplasm when an enzyme attaches a third phosphate to the ADP (both ADP and the phosphates are the substrates on which the enzyme acts) Chemiosmosis, shown in Figure 4, involves more than the single enzyme of substrate- level phosphorylation. Enzymes in chemiosmotic synthesis are arranged in an electron transport chain that is embedded in a membrane. In eukaryotes this membrane is in either the chloroplast or mitochondrion . According to the chemiosmosis hypothesis proposed by Peter Mitchell in 1961, a special ATP-synthesizing enzyme is also located in the membranes. Mitchell would later win the Nobel Prize for his work.
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During chemiosmosis in eukaryotes, H + ions are pumped across an organelle membrane by membrane "pump proteins" into a confined space (bounded by
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Unformatted text preview: membranes) that contains numerous hydrogen ions. This is shown in Figure 4 and 5. The energy for the pumping comes from the coupled oxidation-reduction reactions in the electron transport chain . Electrons are passed from one membrane-bound enzyme to another, losing some energy with each tansfer (as per the second law of thermodynamics ). This "lost" energy allows for the pumping of hydrogen ions against the concentration gradient (there are fewer hydrogen ions outside the confined space than there are inside the confined space). The confined hydrogens cannot pass back through the membrane. Their only exit is through the ATP synthesizing enzyme that is located in the confining membrane. As the hydrogen passes through the ATP synthesizing enzyme, energy from the enzyme is used to attach a third phosphate to ADP, converting it to ATP....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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How to Make ATP - membranes) that contains numerous...

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