OXIDATIVE PHOSPHORYLATION
What compound is formed as a final product of the electron transport chain?
2 water molecules are formed as the final product of the electron transport chain.
During oxidative phosphorylation, what molecule is being phosphorylated?
During oxidative phosphorylation, ADP molecules are being phosphorylated to form ATP molecules.
Explain why energy is required to move the hydrogen ions across the membrane in the direction indicated in Model 1.
Energy is required to move the hydrogen ions across the membrane in the direction indicated in Model 1 because the hydrogen ions are moving against the concentration gradient by active transport which needs energy to work.
Would free energy be required for the hydrogen ions to move in the direction shown in Model 2? Explain your reasoning.
Free energy would not be required for the hydrogen ions to move in the direction shown in Model 2 because the hydrogen ions are moving through the process of facilitated diffusion (not moving against concentration gradient) because the ions are moving down the concentration gradient through an embedded protein.
Which phase(s) of cellular respiration would be unaffected by the lack of mitochondria in a cell?
Glycolysis would be unaffected by the lack of mitochondria in a cell.
Is any ATP produced in the electron transport chain?
No, no ATP is produced in the electron transport chain
Is any ATP used in the electron transport chain?
No, no ATP is used in the electron transport chain
What molecule is the final electron acceptor after the electron has moved through the electron transport chain?
Oxygen acts as the final electron acceptor and accepts the electron after it has moved through the electron transport chain
Where do the electron acceptor molecules (for oxidative phosphorylation) come from?
The electron acceptor molecules come from glycolysis, the link reaction, and krebs cycle.
Is the release of an electron from one of these electron acceptor molecules oxidation or reduction?
The release of an electron from one of these electron acceptor molecules is oxidation, because there is a decrease in charge
When the electrons are released from the electron acceptor molecules (in oxidative phosphorylation), what else is produced?
When the electrons are released from the electron acceptor molecules H+ ions are also produced.
Under ideal conditions each NADH molecule will result in three ATP molecules, and each FADH2 molecule will result in two ATP molecules during oxidative phosphorylation. Calculate the total number of ATP molecules that might be produced in this phase of cellular respiration from one glucose molecule.
1 glucose = 5 NADH and 1 FADH2 5 NADH = 15 ATP 1 FADH2 = 2 ATP Therefore, under ideal conditions, one molecule of glucose will produce 17 ATP molecules.
According to Model 1, how do the hydrogen ions reach this area (inter membrane space)?
According to Model 1, hydrogen ions reach this area through embedded protein channels (powered by electron transport chains) that are located in the inner mitochondrial membrane from the mitochondrial matrix.
Complete the table below to identify the phase of cellular respiration where each of the reactants are used, the products are produced, and the location in the cell where that phase occurs.
Glucose (reactant): used in glycolysis, which occurs in cytoplasm Oxygen (reactant): used in oxidative phosphorylation, which occurs in mitochondrial matrix CO2 (product): produced in link reaction, which occurs in mitochondrial matrix H2O (product): produced in oxidative phosphorylation, which occurs in mitochondrial matrix ATP (product): produced in glycolysis, krebs, and oxidative phosphorylation, which occur in mitochondria & cytoplasm
Because of its role in aerobic respiration, oxygen is essential for most living things on Earth. In complete sentences, describe the role of molecular oxygen (O2) in aerobic respiration.
In aerobic respiration, O2 acts as the final electron acceptor at the end of the electron transport chain, allowing for the production of many molecules of ATP from one molecule of glucose. If O2 were not present, only a few ATP could be produced (by means of alternative processes such as fermentation). Along with forming ATP, molecular oxygen also combines with glucose (reactants) to form carbon dioxide and water (products) through aerobic cellular respiration.
Considering all the stages of cellular respiration (glycolysis, link, Krebs cycle, and oxidative phosphorylation) how many ATP molecules are produced from one glucose molecule, assuming ideal circumstances?
Under ideal circumstances, 38 ATP molecules are produced from one glucose molecule through the stages of cellular respiration.
What is the name of the embedded protein that provides a channel for the hydrogen ions to pass through the membrane?
ATP synthase is the embedded protein that provides a channel for the hydrogen ions to pass through the membrane
Describe the movement of hydrogen ions through the membrane illustrated in Model 2.
Hydrogen ions diffuse from the intermembrane space (in between outer and inner mitochondrial membranes), where there is a relatively higher concentration of H+ ions, through the ATP synthase protein, to the mitochondrial matrix, where there is a relatively lower concentration of H+ ions.
During glycolysis the enzyme hexokinase uses ATP to transfer a phosphate to glucose to form fructose-diphosphate. Suppose that a cell has only glucose available for energy and that the activity of hexokinase is suddenly stopped. Explain in detail what is most likely to occur in the cell.
If the cell only has glucose available for energy and the activity of hexokinase is suddenly stopped, the cell will be unable to form fructose-diphosphate, hindering the following steps of glycolysis and thus preventing cellular respiration from properly occurring. You cannot make pyruvate or carry out the rest of glycolysis; the entire pathway is lost.
The link reaction and Krebs cycle occur in the cytoplasm of prokaryotes in the same way that they occur in the mitochondria of eukaryotes. However, a concentration gradient across a membrane is a requirement of the electron transport chain. Propose an alternate site for this phase of cellular respiration in prokaryotic cells.
In prokaryotic cells, this phase of cellular respiration could occur at the cell membrane, as a concentration gradient, and thus the electron transport chain, could be established in this section of the prokaryotic cell.
Substrate level phosphorylation is the term used for phosphorylation that removes a phosphate from one molecule and joins it to another molecule. Oxidative phosphorylation is the term used for the attachment of free inorganic phosphate to a molecule. Identify the phases of cellular respiration that use substrate level phosphorylation and that use oxidative phosphorylation.
Substrate level phosphorylation: used in glycolysis and krebs cycle stages of cellular respiration Oxidative phosphorylation: used in oxidative phosphorylation stage of cellular respiration
The flow of hydrogen ions through the protein channel provides free energy to do work. What process in Model 2 requires energy?
The phosphorylation of ADP to ATP by the addition of a phosphate group requires energy
Describe the region in Model 1 where the highest concentration of hydrogen ion (H+) is located.
The region in Model 1 where the hydrogen ion concentration is located is the intermembrane space which is in between the outer mitochondrial membrane and the inner mitochondrial membrane.
Which side of the inner mitochondrial membrane would have a higher pH?
The side of the inner mitochondrial membrane that would have a higher pH would be the inner membrane because it has a low number of hydrogen ions.