BioUnit2chp9
State the basic function of fermentation
A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
Describe the role of NAD+ in cellular respiration
A location where dehydrogenase enzymes transfer electrons; NAD acts as an electron and hydrogen carriers in some oxidation-reduction reactions.
In general terms, explain how the exergonic "slide" of electrons down the electron transport chain is coupled to the endergonic production of ATP by chemiosmosis
As electrons pass or slide down the electron transport chain energy is released. This is an exergonic reaction because energy is being released as electrons pass from carier to carrier in the ETC. This energy is used by ATP synthase to create ATP. This is an endergonic reactions because it needs energy to take place. Energy is needed to produce ATP.
Write the summary equation for cellular respiration. Write the specific chemical equation for the degradation of glucose
C6H12O6 (glucose) + 6O2 (oxygen) ---------> 6CO2 (carbon dioxide) + 6H2O (water) + energy; same just minus energy
Describe how food molecules other than glucose can be oxidized to make ATP
Each NADH and FADH2 molecule formed represents stored energy... contain high energy electrons from food molecules which are carried to an electron transport chain; Plants manufacture their own food by photosynthesis using energy from sunlight. Cells harvest the chemical energy stored in organic molecules and use it to regenerate ATP, the molecule that drives most cellular work. ADP + P + energy ATP
Explain in general terms how redox reactions are involved in energy exchanges
Electrons are transferred from one atom to another, or move to a lower energy orbital on the covalent bond of an atom
Compare the processes of fermentation and cellular respiration
Fermentation is the process of deriving energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. This is in contrast to cellular respiration, where electrons are donated to an exogenous electron acceptor, such as oxygen, via an electron transport chain
Describe the point at which glucose is completely oxidized during cellular respiration
Glucose is completely oxidized after chemiosmosis because that's when the final products of Glycolysis and The Citric Acid Cycle are used creating the final 36 to 38 ATP molecules. The final products that are used are NADH and FADH2 which are needed in the electron transport chain and ultimately Chemiosmosis.
Explain how glycolysis and the citric acid cycle can contribute to anabolic pathways
Glycolysis and the citric acid cycle contribute by making ATP, they also generate electrons for the Electron Transport Chain (ETC). The ETC then uses those electrons to make a proton gradient in the mitochondria which in turn powers the enzyme ATP-synthase to make a whole bunch of ATP.
Summarize the net ATP yield from the oxidation of a glucose molecule by constructing an ATP ledger
Glycolysis--2 net ATP from substrate-level phosphorylation 2 NADH yields 6 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation;Transition Reaction--2 NADH yields 6 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation;Citric Acid Cycle--2 ATP from substrate-level phosphorylation 6 NADH yields 18 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation 2 FADH2 yields 4 ATP (assuming 2 ATP per FADH2) by oxidative phosphorylation Total Theoretical Maximum Number of ATP Generated per Glucose in Prokaryotes--38 ATP: 4 from substrate-level phosphorylation; 34 from oxidative phosphorylation; In eukaryotic cells, the theoretical maximum yield of ATP generated per glucose is 36 to 38, depending on how the 2 NADH generated in the cytoplasm during glycolysis enter the mitochondria and whether the resulting yield is 2 or 3 ATP per NAD
Compare the fate of pyruvate in alcohol fermentation and lactic acid fermentation
In alcoholic fermentation, pyruvic acid is converted to ethanol. Carbon dioxide is released, and NADH is recycled into NAD+. In lactic acid fermentation, pyruvic acid is converted to lactic acid. NADH is recycled into NAD+
Describe how the carbon skeleton of glucose changes as it proceeds through glycolysis
In glycolysis, the skeleton will change in two ways. The ring must be opened, and then the glucose will be cleaved into 2 3-carbon molecules known as glyceraldehyde. These are straight chained.
Describe the evidence that suggests that glycolysis is an ancient metabolic pathway
It occurs, with variations, in nearly all organisms, both aerobic and anaerobic. The wide occurrence of glycolysis indicates that it is one of the most ancient known metabolic pathways.[3] It occurs in the cytosol of the cell.
In general terms, explain the role of the electron transport chain in cellular respiration
NADPH passes electrons to the electron transport chain, from which they eventually combine with hydrogen ions and oxygen to form water.
Define oxidation and reduction
Oxidation is the loss of an electron Reduction is gain of an electron OIL RIG Oxidation is Loss Reduction is Gain
Explain how ATP production is controlled by the cell. Describe the role that the allosteric enzyme phosphofructokinase plays in this feedback control
Phosphofructokinase (PFK) is a glycolytic enzyme that catalyzes the irreversible transfer of a phosphate from ATP to fructose-6-phosphate: fructose-6-phosphate + ATP fructose-1,6-bisphosphate + ADP In part because of the irreversible nature of this step in glycolysis, PFK is the key regulatory enzyme for glycolysis. When ATP levels are high in the cell, the cell no longer needs metabolic energy production to occur. In this case, PFK's activity is inhibited by allosteric regulation by ATP itself, closing the valve on the flow of carbohydrates through glycolysis.
Explain why it is not possible to state an exact number of ATP molecules generated by the oxidation of a molecule of glucose
Phosphorylation and the redox reactions are not directly coupled to each other, so the ratio of number of NADH molecules to number of ATP molecules is not a whole number. The ATP yield varies slightly depending on the type of shuttle used to transport electrons from the cytosol into the mitochondrion. The mitochondrial inner membrane is impermeable to HADH so NADH in the cytosol is separated from the machinery of oxidative phosphorylation. Depending on the type of shuttle in a particular cell type, the electrons are passed either to NAD+ or to FAD in the mitochondrial matrix. 3. The use of proton-motive force generated by the redox reactions of respiration to drive other kinds of work.
Distinguish between substrate level phosphorylation and oxidative phosphorylation
Substrate-level phosphorylation is when ATP is formed by the transferring of a phosphate group to ADP from another substrate, which is assisted by an enzyme. (Kreb's Cycle and glycolysis). Oxidative is when ADP and a phosphate group bond due to a redox reaction (chemiosmosis).
Explain where and how the respiratory electron transport chain creates a proton gradient. Explain why this gradient is described as a proton motive force
The electron transport chain pumps protons from the matrix of the mitochondrion through the inner membrane and out to the intermembrane space (the interior of the cristae). The interior of the cristae becomes positively charged relative to the mitochondrion matrix, which creates a strong electrochemical gradient which favors the movement of protons back into the matrix.
Explain why ATP is required for the preparatory steps of glycolysis
Two molecules of ATP are consumed as glucose is split into two three-carbon sugars (glyceraldehyde 3-phosphate).The conversion of these molecules to pyruvate produces two NADH and four ATP by substrate-level phosphorylation.
Explain why ATP synthase is considered a molecular rotary motor
While the protons diffuse through it, it actually spins to make room for another proton to come through.
Calculate the efficiency of respiration in generating ATP
around 38-39%; Oxidation of glucose = -686 kcal/mol Production of ATP = +7.3 kcal/mol 32 ATP x 7.3 = ~234 kcal/mol 234/686 = ~34%
Describe where pyruvate is oxidized to acetyl CoA, what molecules are produced, and how this process links glycolysis to the citric acid cycle
pyruvate is oxidized to Acetyl-CoA in the cytoplasm. The molecules produced are 2 carbon dioxide molecules, 2 NADH molecules, and 2 Acetyl CoA's. ;The process converts pyruvate to Acetyl CoA because otherwise, it cannot be introduced to the Citric Acid Cycle.
