Cellular Respiration (College Board AP® Biology): Flashcards
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Define cellular respiration.
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Cards in this collection (48)
Define cellular respiration.
Cellular respiration is a chemical process that releases energy from biological macromolecules (such as glucose) to produce ATP.
Define fermentation.
Fermentation is a chemical reaction, also known as anaerobic respiration, that releases energy from macromolecules in the absence of oxygen.
In which organisms do respiration and/or fermentation take place?
In all living organisms.
Which biological macromolecule is broken down during cellular respiration?
Glucose is broken down to release energy.
What is the word equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water
In eukaryotic cells, aerobic cellular respiration takes place in the .
In eukaryotic cells, aerobic cellular respiration takes place in the mitochondria.
Aerobic respiration in eukaryotes involves a series of reactions that capture energy from macromolecules.
Aerobic respiration in eukaryotes involves a series of enzyme-controlled reactions that capture energy from macromolecules.
Fermentation releases energy from macromolecules in the absence of .
Fermentation releases energy from macromolecules in the absence of oxygen.
True or False?
Respiration and fermentation are characteristic of all forms of life.
True.
All living organisms carry out respiration and/or fermentation to release energy from biological macromolecules.
True or False?
Fermentation releases more energy than aerobic cellular respiration.
False.
Fermentation releases less energy than aerobic cellular respiration.
True or False?
Cellular respiration is the same as breathing.
False.
Cellular respiration is a chemical process that releases energy inside cells; it should not be confused with breathing.
Why can the products of fermentation vary between different organisms?
Because fermentation pathways differ between types of organisms, so the products (such as alcohol or lactic acid) can vary.
Define glycolysis.
Glycolysis is the first stage of cellular respiration, in which glucose is broken down into two molecules of pyruvate in the cytosol of the cell.
Glycolysis takes place in the of the cell.
Glycolysis takes place in the cytosol of the cell.
What are the products of glycolysis (per molecule of glucose)?
2 pyruvate molecules
a net gain of 2 ATP
2 NADH
True or False?
Glycolysis produces a net gain of two molecules of ATP.
True.
Some ATP is used during the early part of glycolysis, so the overall net gain is two molecules of ATP per glucose.
How is pyruvate transported from the cytosol into the mitochondrion?
By active transport across the double membrane of the mitochondrion.
True or False?
Two molecules of pyruvate enter the mitochondrion per molecule of glucose.
True.
Glycolysis produces two pyruvate molecules per glucose, so two pyruvate molecules enter the mitochondrion and are oxidized.
When pyruvate is oxidized in the mitochondrion, it is converted into , which then enters the Krebs cycle.
When pyruvate is oxidized in the mitochondrion, it is converted into acetyl CoA, which then enters the Krebs cycle.
What is produced when pyruvate is oxidized in the mitochondrion?
acetyl coenzyme A (acetyl CoA)
NADH (from the reduction of NAD+)
carbon dioxide
Define Krebs cycle.
The Krebs cycle is a series of enzyme-controlled reactions in the mitochondrial matrix, also known as the citric acid cycle, that uses acetyl CoA to produce ATP, NADH and FADH2 while releasing carbon dioxide.
The Krebs cycle takes place in the of the mitochondria.
The Krebs cycle takes place in the matrix of the mitochondria.
What are the products of the Krebs cycle?
ATP (from ADP and inorganic phosphate)
NADH and FADH2
carbon dioxide
True or False?
The carbon dioxide released during the Krebs cycle is transferred to the electron transport chain.
False.
Carbon dioxide is released as a waste product. It is NADH and FADH2 that are transferred to the electron transport chain.
Define electron transport chain (ETC).
Electron transport chain (ETC) is a series of electron acceptor proteins on the inner mitochondrial membrane that transfer electrons through oxidation-reduction reactions, establishing an electrochemical gradient across the membrane.
Which two molecules deliver electrons to the electron transport chain, and where do they come from?
NADH and FADH2, produced during the Krebs cycle and glycolysis.
In eukaryotes, where do the reactions of the electron transport chain take place?
In the mitochondria, on the inner mitochondrial membrane.
As electrons pass along the ETC, energy is used to transport protons from the matrix into the , building up a proton gradient.
As electrons pass along the ETC, energy is used to transport protons from the matrix into the intermembrane space, building up a proton gradient.
True or False?
The pH inside the mitochondrial matrix is lower than in the intermembrane space.
False.
Protons are pumped out of the matrix, so the matrix has a lower proton concentration and therefore a higher pH than the intermembrane space.
Define chemiosmosis.
Chemiosmosis is the diffusion of protons back across the inner mitochondrial membrane, down their concentration gradient, through a channel associated with ATP synthase.
Define oxidative phosphorylation.
Oxidative phosphorylation is the formation of ATP from ADP and inorganic phosphate, driven by the flow of protons through ATP synthase by chemiosmosis.
How does folding of the inner mitochondrial membrane support ATP production?
The folding increases the surface area of the membrane, which allows more ATP to be synthesized.
What is the terminal electron acceptor at the end of the ETC in aerobic respiration, and what is produced?
Oxygen is the final electron acceptor; it combines with electrons and protons to form water.
What terminal electron acceptors do anaerobic prokaryotes use instead of oxygen?
Other molecules, such as nitrate and sulfate.
True or False?
In prokaryotes, the electron transport chain occurs across folded regions of the plasma membrane.
True.
Prokaryotes lack membrane-bound organelles, so the ETC and the movement of protons take place across the plasma membrane instead of an inner mitochondrial membrane.
Decoupling electron transport from oxidative phosphorylation releases energy as , which endothermic organisms can use to regulate body temperature.
Decoupling electron transport from oxidative phosphorylation releases energy as heat, which endothermic organisms can use to regulate body temperature.
Define fermentation.
Fermentation is a process that allows glycolysis to keep producing ATP in the absence of oxygen, generating organic molecules such as alcohol or lactic acid.
Where does the ATP produced during fermentation come from?
It comes from glycolysis, which can take place without oxygen.
How does fermentation allow glycolysis to continue?
Fermentation regenerates NAD from NADH.
This NAD can re-enter glycolysis, so ATP production continues.
Fermentation allows glycolysis to proceed in the absence of .
Fermentation allows glycolysis to proceed in the absence of oxygen.
True or False?
Fermentation produces more ATP than aerobic cellular respiration.
False.
Fermentation produces less ATP than aerobic cellular respiration, because it relies only on glycolysis.
True or False?
Respiration and fermentation are characteristic of all forms of life.
True.
All living organisms use respiration and fermentation to obtain energy from biological macromolecules.
What are the two main organic products of fermentation?
Alcohol (ethanol) and lactic acid.
Which type of fermentation takes place in yeast cells?
Alcohol fermentation, which also releases carbon dioxide.
Which type of fermentation takes place in human muscle cells?
Lactic acid fermentation, which occurs when oxygen cannot be supplied to the muscles quickly enough.
In muscle cells, fermentation produces when oxygen cannot be supplied quickly enough.
In muscle cells, fermentation produces lactic acid when oxygen cannot be supplied quickly enough.
Define alcohol fermentation.
Alcohol fermentation is fermentation in yeast cells that produces ethanol and releases carbon dioxide, regenerating NAD so glycolysis can continue.
Define lactic acid fermentation.
Lactic acid fermentation is fermentation in muscle cells that produces lactic acid, regenerating NAD so glycolysis can continue when oxygen is in short supply.
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