Glycolysis, the Krebs cycle and oxidative phosphorylation with full ATP accounting: flashcards and practice questions. Free, no sign-up.
Subject: biology
What is the primary reason cells break down glucose gradually through a series of enzyme-catalyzed reactions in cellular respiration, rather than in a single step?
Answer: To capture as much energy as possible in ATP, minimizing loss as heat.
Cellular respiration is a controlled, stepwise process to maximize the capture of energy in ATP, preventing its dissipation as heat. This gradual release allows for efficient energy transfer.
A cell is performing anaerobic respiration. What is the most significant consequence of the absence of oxygen for its ATP production compared to aerobic conditions?
Answer: The cell will produce only a net 2 ATP per glucose, primarily because the electron transport chain cannot run.
Without oxygen, the electron transport chain, which produces the vast majority of ATP (26-28 ATP), cannot operate. This leaves only glycolysis, yielding a net 2 ATP per glucose.
How does the structure of the inner mitochondrial membrane contribute to the high ATP yield during oxidative phosphorylation?
Answer: Its folds, called cristae, increase the surface area for the electron transport chain and ATP synthase.
The inner mitochondrial membrane is folded into cristae, which significantly increases its surface area. This larger surface area accommodates more electron transport chain complexes and ATP synthase enzymes, facilitating a higher rate of oxidative phosphorylation and thus greater ATP production.
Why is the regeneration of NAD⁺ from NADH critical for the continuous operation of glycolysis under both aerobic and anaerobic conditions?
Answer: Glycolysis requires a steady supply of NAD⁺ to accept electrons and continue breaking down glucose.
NAD⁺ acts as an electron carrier in glycolysis, picking up electrons to become NADH. If NAD⁺ is not regenerated, glycolysis would quickly deplete its supply of NAD⁺ and halt, stopping the breakdown of glucose and any ATP production from this pathway.
What is the definition of 'aerobic respiration'?
Answer: Complete breakdown of glucose using oxygen, yielding CO₂, water, and about 30+ ATP.
Aerobic respiration is defined as the complete breakdown of glucose using oxygen, resulting in carbon dioxide, water, and a significant amount of ATP (around 30+).
What is the definition of 'anaerobic respiration'?
Answer: Partial breakdown of glucose without oxygen, yielding only the 2 ATP of glycolysis.
Anaerobic respiration is characterized by the partial breakdown of glucose in the absence of oxygen, resulting in a much lower ATP yield (only the net 2 ATP from glycolysis).
What is the definition of 'glycolysis'?
Answer: Splitting of glucose into two pyruvate in the cytoplasm.
Glycolysis is the initial stage of cellular respiration where one six-carbon glucose molecule is split into two three-carbon pyruvate molecules, occurring in the cytoplasm.
What is 'pyruvate'?
Answer: A three-carbon product of glycolysis.
Pyruvate is the three-carbon molecule that results from the splitting of glucose during glycolysis.
What is 'acetyl-CoA'?
Answer: A two-carbon fragment, bound to coenzyme A, that carries carbon into the Krebs cycle.
Acetyl-CoA is formed from pyruvate in the link reaction; it's a two-carbon acetyl group attached to coenzyme A, which then enters the Krebs cycle.
What is 'substrate-level phosphorylation'?
Answer: Making ATP by transferring a phosphate directly from an intermediate to ADP.
Substrate-level phosphorylation is a direct method of ATP synthesis where a phosphate group is transferred from a high-energy intermediate molecule to ADP.
What is 'oxidative phosphorylation'?
Answer: Making ATP using energy from electrons passed down the electron transport chain.
Oxidative phosphorylation is the process where ATP is synthesized using the energy released as electrons are passed along the electron transport chain, ultimately involving oxygen as the final acceptor.
What is 'chemiosmosis'?
Answer: ATP synthesis driven by protons flowing through ATP synthase down their gradient.
Chemiosmosis is the specific mechanism within oxidative phosphorylation where the flow of protons (H⁺) down their electrochemical gradient through ATP synthase drives the synthesis of ATP.
What is the 'final electron acceptor' in aerobic respiration?
Answer: Oxygen
At the end of the electron transport chain, oxygen accepts electrons and protons to form water. This is its crucial role in aerobic respiration.
What is the 'matrix' in the context of cellular respiration?
Answer: The fluid interior of the mitochondrion where the link reaction and Krebs cycle occur.
The mitochondrial matrix is the fluid-filled space within the inner membrane where the link reaction and the Krebs cycle enzymes are located.
What are 'cristae'?
Answer: Folds of the inner mitochondrial membrane that increase surface area for the electron transport chain.
Cristae are the characteristic folds of the inner mitochondrial membrane, which serve to greatly increase the surface area available for the electron transport chain and ATP synthase.
What is 'oxygen debt'?
Answer: The extra oxygen consumed after exercise to break down accumulated lactate.
Oxygen debt refers to the increased oxygen intake after strenuous exercise, needed to metabolize the lactate produced during anaerobic respiration back into glucose or pyruvate.
What is the 'electron transport chain'?
Answer: A series of protein complexes in the inner membrane that pass electrons and pump protons.
The electron transport chain is a crucial component of oxidative phosphorylation, located in the inner mitochondrial membrane, where electrons are passed along protein complexes to pump protons and generate a gradient for ATP synthesis.
What is 'ATP synthase'?
Answer: An enzyme that makes ATP as protons flow through it back into the matrix.
ATP synthase is a key enzyme in chemiosmosis, utilizing the energy from the flow of protons down their electrochemical gradient to synthesize ATP from ADP and inorganic phosphate.
What is the 'intermembrane space' in the context of cellular respiration?
Answer: The compartment between the mitochondrial membranes where protons accumulate.
The intermembrane space is the region between the outer and inner mitochondrial membranes where protons are pumped by the electron transport chain, creating the proton gradient.
The process by which cells break down glucose to release energy and capture it in the form of ATP is called {0}.
Answer: cellular respiration
Cellular respiration is the fundamental process cells use to extract energy from glucose.
Cells use {0} as the molecule to transfer energy from energy-releasing reactions to energy-requiring ones.
Answer: ATP
ATP (adenosine triphosphate) is the primary energy currency of the cell.
The complete breakdown of glucose using oxygen, yielding CO₂, water, and about 30+ ATP, is known as {0}.
Answer: aerobic respiration
Aerobic respiration is characterized by its use of oxygen and high ATP yield.
The partial breakdown of glucose without oxygen, yielding only the 2 ATP of glycolysis, is called {0}.
Answer: anaerobic respiration
Anaerobic respiration occurs in the absence of oxygen and produces much less ATP than aerobic respiration.
{0} is the stage of cellular respiration that splits one six-carbon glucose into two three-carbon pyruvate molecules.
Answer: Glycolysis
Glycolysis is the initial stage of glucose breakdown, occurring in the cytoplasm.
The fluid interior of the mitochondrion, called the {0}, contains the enzymes of the Krebs cycle.
Answer: matrix
The mitochondrial matrix is where the link reaction and Krebs cycle take place.
{0} is the process of making ATP using energy from electrons passed down the electron transport chain.
Answer: Oxidative phosphorylation
Oxidative phosphorylation is the main ATP-producing stage in aerobic respiration.
NADH and FADH₂ hand their electrons to the {0}, a series of protein complexes in the inner mitochondrial membrane.
Answer: electron transport chain
The electron transport chain is crucial for establishing the proton gradient used in ATP synthesis.
ATP synthesis driven by protons flowing through ATP synthase down their gradient is known as {0}.
Answer: chemiosmosis
Chemiosmosis is the specific mechanism by which the proton gradient is used to generate ATP.
{0} uses pyruvate to re-oxidize NADH back to NAD⁺ so glycolysis can keep running without oxygen.
Answer: Fermentation
Fermentation is essential for regenerating NAD⁺ in anaerobic conditions, allowing glycolysis to continue.
{0} picks up electrons (with a proton) to become NADH, acting as an electron carrier.
Answer: NAD⁺
NAD⁺ is a key coenzyme that carries high-energy electrons during cellular respiration.
The coenzyme {0} picks up electrons to become FADH₂, delivering them to the electron transport chain.
Answer: FAD
FAD is another important electron carrier, similar to NAD⁺.
Most of aerobic respiration, including the Krebs cycle and electron transport chain, happens in the {0}.
Answer: mitochondrion
The mitochondrion is often called the 'powerhouse' of the cell due to its role in aerobic respiration.
loading your study session...