Chapter 9 Cellular Respiration and Fermentation Flashcards
Adenosine Triphosphate
A molecule consisting of adenine, a sugar, and three phosphate groups that can be hydrolyzed to release energy. Universally used by cells to store and transfer energy.
Adenosine diphosphate
A molecule consisting of adenine, a sugar, and two phosphate groups. Addition of a third phosphate group produces adenosine triphosphate (ATP).
Glucose
Six-carbon monosaccharide whose oxidation in cellular respiration is the major source of ATP in animal cells.
What is the most common fuel in organisms?
Glucose
Why does ATP make things happen in cells?
Because it has a great deal if potential energy
______________ energy in an electro is based on its position relative to other electrons and protons in the nuclei of nearby atoms.
Potential Energy
Exergonic
Referring to a chemical reaction that can occur spontaneously, releasing heat and/or increasing entropy, and for which the Gibbs free-energy change (ΔG) ≫ 0. Compare with endergonic.
Endergonic
Referring to a chemical reaction that requires an input of energy to occur and for which the Gibbs free-energy change (ΔG) ≫ 0. Compare with exergonic.
Why is the hydrolysis of ATP exergonic?
The entropy of the product molecules is much higher than that of the reactants and because there is a large drop in potential energy when ADP and Pi are formed from ATP.
Phosphorylation or phosphorylate
The addition of a phosphate group to a molecule.
Why is the phosphorylation of proteins exergonic?
The electrons in ADP and the phosphate group ave much less potential energy than they did in ATP.
Explain how ATP has high potential energy.
ATP’s high potential energy results, in part, from the four negative charges clustered in its three phosphate groups. The negative charges repel each other, raising the potential energy of the electrons.
How does protein move?
When proteins are phosphorylated or an ATP molecule binds to them, they often change shape in a way that alters their activity. (Phosphorylation changes the shape and activity of proteins.)
***Protein movement either in response to phosphorylation or to binding of an entire ATP molecule is what transport materials inside cells, power flagella or cilia, and pumps ions across membranes. It also drives endergonic reactions required for life.
Reduction-oxidation reactions or redox reactions
are a class of chemical reactions that involve the loss or gain of one or more electrons.
Why are redox reactions central?
because the drive the formation of ATP
In a redox reaction, the atom that loses one or more electrons is _________________.
Oxidized
In a redox reaction, the atom that gains an electron is __________________.
reduced
What does the mnemonic Oil Rig stand for?
Oxidation is lost; Reduction is gain
What does the mnemonic Leo the lion goes Ger mean?
Loss of electrons is oxidation; gain of electrons is reduction
What does the following statement mean?
Oxidation evens are always paired with a reduction.
A reactant that act as an electron donor is always associated with a reactant that acts as an electron acceptor. (if on atom loses an electron, another has to gain it)
In may redox reactions in biology, understanding whee oxidation and reduction have occurred becomes a matter of following _____________ atoms.
hydrogen
ex:
NAD+ is reduced to form NADH, NADH readily donates electrons to other molecule, as a result, it is know as an electron carrier
Which term describes the degree to which an element attracts electrons?
Reduction.
Polarity.
Oxidation.
Electronegativity.
Electronegativity is the tendency of an atom to attract electrons toward itself
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Polar and nonpolar.
Ionic and covalent.
Proton and electron.
Anion and cation.
Anion and cation. Each atom will carry a charge from the transfer of electrons.
Which of the following statements is true of the bonds in a water molecule?
The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1.
Oxygen acts as the electron acceptor and is oxidized.
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero.
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
Correct. The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero.
Which of the following statements is not true of most cellular redox reactions?
The electron acceptor is reduced.
A hydrogen atom is transferred to the atom that loses an electron.
The reactant that is oxidized loses electrons.
Changes in potential energy can be released as heat.
Your Answer:
A hydrogen atom is transferred to the atom that loses an electron.
Correct. A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic.
Redox.
Polar covalent.
Nonpolar covalent.
Your Answer:
Ionic.
Correct. The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells
Gaseous hydrogen burns in the presence of oxygen to form water:
2H2 + O2 → 2H2 O + energy
Which molecule is oxidized and what kind of bond is formed?
Oxygen, polar.
Oxygen, nonpolar.
Hydrogen, polar.
Hydrogen, nonpolar.
Your Answer:
Hydrogen, polar.
Correct. Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself.
A reduction-oxidation (redox) reaction always involves two events:
one substance loses
electrons and is said to be oxidized, while another substance gains electrons and is said to
be reduced.
Sodium chloride, or table salt, offers an example of atoms that have undergone oxidation and reduction to become ions. When sodium and chlorine react to form sodium chloride, one electron is completely transferred from the sodium atom to the chlorine atom.
What it the result?
The result is a sodium cation and a chloride anion.
In this redox reaction, the sodium atom lost an electron—it was oxidized.
The new sodium ion is a positively charged cation. The chlorine atom gained an electron—it was reduced.
The new chloride ion is a negatively charged anion.
In redox reactions, electrons can be transferred completely from one molecule or atom to
another, forming an __________________ bond, or they can simply shift positions in ____________________bonds.
ionic;covalent
When electrons are shared equally, the bonds are _______________________
nonpolar
In carbon dioxide, the nucleus of the carbon atom holds the electrons less tightly. Carbon
has been __________________ electrons. In water, the nucleus of the oxygen atom holds the
electrons more tightly. Oxygen has been _______________________ electrons.
oxidized—it “lost”
reduced—it “gained”
Because the atomic nuclei of the product molecules hold the electrons more tightly than they were held in the reactant molecules, the products have___________________. Such reactions tend to be spontaneous, or ________________, and release free energy.
lower potential energy
exergonic
Anion
An ion with a negative electrical charge as a result of having gained electrons.
cation
An ion with a positive electrical charge as a result of having lost electrons.
covalent bond
A bond in which electrons are shared between atoms or molecules.
exergonic
Producing heat or energy. An exergonic reaction is spontaneous and occurs
when the products have lower potential energy than the reactants.
ion
An electrically charged atom or molecule.
ionic bond
A bond in which electrons are completely transferred from one atom or molecule
to another.
nonpolar bond
A symmetric bond that results when electrons are shared equally.
oxidation
The loss of electrons during a redox reaction.
polar bond
An asymmetric bond that results when electrons are transferred in ionic bonding
or when electrons are shared unequally in covalent bonding.
potential energy
potential energy The energy stored in matter through its position or its shape.
The gain of electrons during a redox reaction.
reduction
A class of chemical reactions that involves the loss and gain of electrons.
reduction-oxidation (redox) reaction
nonpolar bond
A symmetric bond that results when electrons are shared equally.
oxidation
The loss of electrons during a redox reaction.
polar bond
An asymmetric bond that results when electrons are transferred in ionic bonding
or when electrons are shared unequally in covalent bonding.
potential energy
potential energy The energy stored in matter through its position or its shape.
The gain of electrons during a redox reaction.
reduction
A class of chemical reactions that involves the loss and gain of electrons.
reduction-oxidation (redox) reaction
When glucose burns, the change in potential energy is converted to ______________.
kinetic energy in the form of heat
In cells, the change in free energy that occurs during the oxidation of glucose is used to synthesize ______________ from _____________ and __________.
ATP, ADP, Pi
ATP contains a cluster of __________ phosphate groups
three
What happens to ATP or phosphate groups from ATP when they bind to proteins or other molecules?
they gain a great deal of potential energy and often change shape in the process.
What happens to electrons when a redox reaction occurs?
electrons change position
Explain why ATP has such high potential energy.
In part, because its three phosphate groups have four negative charges in close proximity. The electrons repulse each other raising their potential energy.
Explain whey molecules with many C-H bonds store more potential energy than molecules with many C-O bonds.
Electrons in C-O bonds are held more tightly than electrons in C-H bonds so they have lower potential energy.
Why is cellular respiration the primary source of ATP in most organism?
because cellular respiration is more efficient that fermentation
What are four steps in the cellular respiration process?
1) Glycolysis
2) Pyruvate processing
3) citric acid cycling
4) electron transport and chemiosmosis
During ________________, one molecule of glucose is broken into two molecules of the three-carbon compound pyruvate. Two ATP molecules are produced from ADP, and one molecule of NAD+ is reduced to form NADH
glycolysis
_______________ pyruvate is processed to form the compound acetyl-CoA. During this step, another molecule of NADH is produced.
Pyruvate
During this phase of cellular respiration, Acetyl-CoA is oxidized to tow molecules of CO2. During this sequence of reactions, more ATP and NADH are produced and FAD is reduced to form another electron carrier, FADH2
citric acid cycle
During this phase, electrons from NADH and FADH2 move through a series of proteins called an electron transport chain (ETC). The potential energy released during these redox reactions is used to create a proton gradient across a membrane; ensuing the flow of protons back across the membrane is used to make ATP.
electron transport and chemiosmosis
What is the end product of photosynthesis?
glucose
_______________ us defined as any suite of reactions that produces ATP in an electron transport chain.
cellular respiration
__________________ occurs when an enzyme catalyzyes the transfer of a phosphate group from a phosphorylated substrate to ADP, form ATP
substrate-level phosphorylation
Why would ATP- a substrate that is required for the reaction in step 3 of glycolysis also inhibit the reaction?
Cells that are able to stop glycolytic reactions when ATP is abundant can conserve their stores of glucose for times when ATP is scarce.
Phosphofrutokinase has _________ binding sites for ATP.
two
In eukaryotes, the pyruvate produced by glycolysis is transported from the _____________ to the ________________.
cytosol to mitochondria.
Glycolysis
A series of 10 chemical reactions that oxidize glucose to produce pyruvate and ATP. Used by all organisms as part of fermentation or cellular respiration.
Cellular Respiration
A common pathway for production of ATP, involving transfer of electrons from compounds with high potential energy (often NADH and FADH) to an electron transport chain and ultimately to an electron acceptor (often oxygen).
Substrate-level phosphorylation
Production of ATP by transfer of a phosphate group from an intermediate substrate directly to ADP. Occurs in glycolysis and in the citric acid cycle.
Phosphofructokinase
The enzyme that catalyzes synthesis of fructose-1,6-bisphosphate from fructose-6-phosphate, a key reaction (step 3) in glycolysis.
Feedback inhibition
A type of metabolic control in which high concentrations of the product of a metabolic pathway inhibit one of the enzymes early in the pathway. A form of negative feedback.
Cristae
Sac-like invaginations of the inner membrane of a mitochondrion. Location of the electron transport chain and ATP synthase.
Mitochondrial Matrix
Central compartment of a mitochondrion, which is lined by the inner membrane; contains the enzymes and substrates of the citric acid cycle and mitochondrial DNA.
Coenzyme CoA
A nonprotein molecule that is required for many cellular reactions involving transfer of acetyl groups ([—COCH3
pyruvate dehydrogenase
A large enzyme complex, located in the inner mitochondrial membrane, that is responsible for conversion of pyruvate to acetyl CoA during cellular respiration.
In eukaryotes, where is pyruvate dehydrogenase located?
in the mitochondrial matrix
In bacteria and archaea, where is the pyruvate dehydrogenase located?
in the cytosol
the citric acid cycle is also know as the ____________ because it involves acids with three carboxyl groups
tricarboxylic acid cycle (TCA)
In bacteria and archaea the enzyme responsible for the citric acid cycle are located in the __________. While in eukaryotes, most of the enzymes responsible for the citric acid cycle are located in the _________________.
cytosol; mitochondrial matrix
Carboxylic acid
Organic acids with the form R-COOH (a carboxyl group).
Citric acid cycle
A series of eight chemical reactions that starts with citrate (citric acid, when protonated) and ends with oxaloacetate, which reacts with acetyl CoA to form citrate—forming a cycle that is part of the pathway that oxidizes glucose to CO. Also known as the Krebs cycle, tricarboxylic acid cycle, and TCA cycle.
Electron transport chain
Any set of membrane-bound protein complexes and smaller soluble electron carriers involved in a coordinated series of redox reactions in which the potential energy of electrons transferred from reduced donors is successively decreased and used to pump protons from one side of a membrane to the other.
ATP synthesis
A large membrane-bound protein complex in chloroplasts, mitochondria, and some bacteria that uses the energy of protons flowing through it to synthesize ATP. Also called F1F0
complex.
Oxidative phosphorylation
Production of ATP molecules from the redox reactions of an electron transport chain.
Electron transport chain
Any set of membrane-bound protein complexes and smaller soluble electron carriers involved in a coordinated series of redox reactions in which the potential energy of electrons transferred from reduced donors is successively decreased and used to pump protons from one side of a membrane to the other.
ATP Synthesis
A large membrane-bound protein complex in chloroplasts, mitochondria, and some bacteria that uses the energy of protons flowing through it to synthesize ATP. Also called FF
complex.
Oxidative phosphorylation
Production of ATP molecules from the redox reactions of an electron transport chain.
Aerobic
Referring to any metabolic process, cell, or organism that uses oxygen as an electron acceptor. Compare with anaerobic.
anaerobic
Referring to any metabolic process, cell, or organism that uses an electron acceptor other than oxygen, such as nitrate or sulfate. Compare with aerobic.
Any of several metabolic pathways that make ATP by transferring electrons from a reduced compound such as glucose to a final electron acceptor other than oxygen. Allows glycolysis to proceed in the absence of oxygen.
Fermentation
Lactic acid fermentation
Catabolic pathway in which pyruvate produced by glycolysis is converted to lactic acid in the absence of oxygen.
Alcohol fermentation
Catabolic pathway in which pyruvate produced by glycolysis is converted to ethanol in the absence of oxygen.
Facultative
Any organism that can perform aerobic respiration when oxygen is available to serve as an electron acceptor but can switch to fermentation when it is not.
Catabolic pathway
Any set of chemical reactions that breaks down larger, complex molecules into smaller ones, releasing energy in the process. Compare with anabolic pathway.
Any set of chemical reactions that synthesizes larger molecules from smaller ones. Generally requires an input of energy. Compare with catabolic pathway.
Anabolic pathway
Which molecule is metabolized in a cell to produce energy for performing work?
Glucose
ADP
ATP
Phosphate
Correct. Glucose is used to produce high-energy ATP in a cell.
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
True
False
Correct. The three phosphate groups in an ATP molecule carry negative charges that strongly repel each other and give ATP a large amount of potential energy.
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
Fermentation
Glycolysis
Krebs cycle
Electron transport chain
Correct. Fermentation is an alternate pathway used when oxygen levels are low.
Which step of the cellular respiration pathway can take place in the absence of oxygen?
Krebs cycle
Fermentation
Electron transport chain
Glycolysis
Glycolysis can take place in the absence of oxygen; its product, pyruvate, enters the cellular respiration pathway or undergoes fermentation depending on the availability of oxygen.
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
Carbon dioxide
NADH
Water
ATP
All of the carbon atoms in glucose are incorporated into carbon dioxide: Two molecules are formed as pyruvate is converted to acetyl CoA, and four molecules are formed during the Krebs cycle.
Which of the following statements about the electron transport chain is true?
NADH and FADH2donate their electrons to the chain.
Water is the last electron acceptor.
Electrons gain energy as they move down the chain.
The electron transport chain is the first step in cellular respiration.
Correct. The electrons lose energy as they move down the chain, and this energy is used to create a proton gradient that drives the synthesis of ATP.
Which stage of glucose metabolism produces the most ATP?
Krebs cycle
Glycolysis
Fermentation of pyruvate to lactate
Electron transport and chemiosmosis
Correct. Electron transport and chemiosmosis (oxidative phosphorylation) can yield around 26 molecules of ATP.
True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
True
False
Correct. Glycolysis takes place in the cytoplasm, whereas the Krebs cycle and the electron transport chain, which generate the largest amounts of ATP during cellular respiration, take place in the mitochondria.
How many NADH are produced by glycolysis?
How many NADH are produced by glycolysis?
3
1
2
4
5
Two NADH molecules are produced by glycolysis.
In glycolysis, ATP molecules are produced by _____.
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
oxidative phosphorylation
photophosphorylation
photosynthesis
cellular respiration
A phosphate group is transferred from glyceraldehyde phosphate to ADP
Which of these is NOT a product of glycolysis?
Which of these is NOT a product of glycolysis?
pyruvate
ATP
FADH2
NADH
FADH2 is a product of the citric acid cycle
In glycolysis, what starts the process of glucose oxidation?
In glycolysis, what starts the process of glucose oxidation?
FADH2
ATP
NADPH
ADP
hexokinase
Some ATP energy is used to start the process of glucose oxidation
In glycolysis there is a net gain of _____ ATP.
In glycolysis there is a net gain of _____ ATP.
4
5
3
1
2
It takes 2 ATP to produce 4 ATP.
Where does each take place?
Glycolysis
Krebs (CAC cycle)
Electron Transport system
Glycolysis- cytosol
Krebs (CAC cycle)- mitochondrial matrix
Electron Transport system- inner mitochondrial membrane
*** mitochondria have 2 membranes
In eukaryotes, glycolysis occurs in the cytosol.
Cytosol - the fluid in which the organelles of the cytoplasm are suspended.
Krebs Cycle occurs in the matrix (fluid portion) of the mitochondrion.
electron transport takes place in the mitochondrial membranes.
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
O2 only pyruvate, ATP, and NADH CO2 only ATP only NADH only pyruvate and ATP only ATP and NADH only
ATP is the main product of cellular respiration that contains energy that can be used by other cellular processes. Some ATP is made in glycolysis. In addition, the NADH and pyruvate produced in glycolysis are used in subsequent steps of cellular respiration to make even more ATP.
In fermentation _____ is reduced and _____ is oxidized.
lactate ... ethanol NADH ... lactate NAD+ ... pyruvate pyruvate ... NADH lactate ... NADH
The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.
In muscle cells, fermentation produces _____.
In muscle cells, fermentation produces _____.
lactate, NADH, and ATP
lactate and NAD+
pyruvate
carbon dioxide, ethanol, NADH, and ATP
carbon dioxide, ethanol, and NAD+
These are the products of fermentation as it occurs in muscle cells.
Which of these enters the citric acid cycle?
Which of these enters the citric acid cycle?
G3P
NADH + H+
glucose
pyruvate
acetyl CoA
Acetyl CoA is a reactant in the citric acid cycle.
In the citric acid cycle, ATP molecules are produced by _____.
In the citric acid cycle, ATP molecules are produced by _____.
photosynthesis
substrate-level phosphorylation
cellular respiration
oxidative phosphorylation
photophosphorylation
A phosphate group is transferred from GTP to ADP.
Which of these is NOT a product of the citric acid cycle?
Which of these is NOT a product of the citric acid cycle?
FADH2
ATP
NADH + H+
acetyl CoA
CO2
Acetyl CoA enters the citric acid cycle.
Which of these reactions requires a net input of energy from its surroundings?
endergonic catabolic ATP --> ADP + P hydrolysis exergonic
The products of endergonic reactions have more potential energy than the reactants.
A(n) _____ reaction occurs spontaneously.
kinetic chemical exergonic endergonic anabolic
In exergonic reactions the products have less potential energy than the reactants.
In cells, what is usually the immediate source of energy for an endergonic reaction?
ADP glucose ATP sugar
The hydrolysis of ATP provides the energy needed for an endergonic reaction.
The reaction ADP + P –> ATP is a(n) _____ reaction.
hydrolysis exergonic endergonic chemical spontaneous
endergonic
Energy has been acquired from the surroundings
The energy for an endergonic reaction comes from a(n) _____ reaction.
anabolic glucose + glucose --> maltose ADP + P --> ATP exergonic synthesis
The energy released by an exergonic reaction can be used to drive an endergonic reaction
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is used to convert an ATP into an AQP. It is acquired by a reactant in an endergonic reaction. It is broken down into one phosphorus and four oxygen atoms. It is acquired by a reactant in a spontaneous reaction. It is acquired by a reactant in an exergonic reaction.
By acquiring the phosphate group the reactant acquires energy.
Select the INCORRECT association.
kinetic energy ... motion potential energy ... positional energy exergonic ... uphill exergonic ... spontaneous enzyme ... protein
exergonic up hill
Exergonic reactions release energy.
What is energy coupling?
What is energy coupling?
the hydrolysis of ATP to ADP + P
the use of an enzyme to reduce EA
a barrier to the initiation of a reaction
the use of energy released from an exergonic reaction to drive an endergonic reaction
a description of the energetic relationship between the reactants and products in an exergonic reaction
the use of energy released from an exergonic reaction to drive an endergonic reaction
Which term describes the degree to which an element attracts electrons?
Polarity. Reduction. Electronegativity. Oxidation.
Electronegativity is the tendency of an atom to attract electrons toward itself.
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation. Polar and nonpolar. Ionic and covalent. Proton and electron.
Each atom will carry a charge from the transfer of electrons.
Anion & Cation
Which of the following statements is true of the bonds in a water molecule?
The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero. Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. Oxygen acts as the electron acceptor and is oxidized.
The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero.
Which of the following statements is not true of most cellular redox reactions?
Changes in potential energy can be released as heat. The electron acceptor is reduced. The reactant that is oxidized loses electrons. A hydrogen atom is transferred to the atom that loses an electron.
A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic. Polar covalent. Nonpolar covalent. Redox.
ionic
The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells.
Gaseous hydrogen burns in the presence of oxygen to form water:
2H2 + O2 → 2H2 O + energy
Which molecule is oxidized and what kind of bond is formed?
Oxygen, polar. Hydrogen, nonpolar. Oxygen, nonpolar. Hydrogen, polar.
hydrogen polar
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
dehydration synthesis dehydration decomposition entropic anabolism hydrolysis
Hydrolysis involves breaking bonds with the addition of water.
