cellular respiration

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ S Lactate + NAD+

pyruvate

Which of the following accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle? (eText Concept 9.3) regeneration of NAD+ removal of coenzyme A release of CO2 and synthesis of NADH formation of CO2 and synthesis of ATP release of CO2 and release of coenzyme A

release of CO2 and synthesis of NADH

Word Roots: -lysis

split (glycolysis: the splitting of glucose into pyruvate)

Word Roots: glyco-

sweet;

Most CO2 from catabolism is released during

the citric acid cycle.

Substrate-level phosphorylation

The enzyme catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism

Beta Oxidation

A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA

Electron Transport Chain

A sequence of electron carrier molecules (membrane proteins) that shuttle electrons down a series of redox reactions that release energy used to make ATP

Glycolysis

A series of reactions that ultimately splits glucose into pyruvate. Occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration

What is pyruvate?

- The end product of glycolysis -The first step in cellular respiration - Stands in the junction between anaerobic and aerobic pathways

Explain concept 9.2: Glycolysis harvests chemical energy by oxidizing glucose to pyruvate

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Explain concept 9.3: After pyruvate is oxidized, the citric acid cycle completes the energy yielding oxidation of organic molecules

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Explain concept 9.5: Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen

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Most of the ATP produced in cellular respiration comes from which of the following processes?

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Relating to aerobic cellular respiration: describe the process of glycolysis, including the major molecules involved and the energy-storing molecules produced.

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Relating to aerobic cellular respiration: describe the process of the Krebs cycle, including the major molecules involved and the energy-storing molecules produced, and explain why the Krebs cycle is considered a cycle.

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Relating to aerobic cellular respiration: describe the roles of NADH, FADH2, and O2 in the electron transport chain part of oxidative phosphorylation

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Relating to aerobic cellular respiration: show the relationship between the electron transport chain, active transport, and facilitated diffusion in the oxidative phosphorylation process of making ATP.

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Relating to aerobic cellular respiration: state the number of ATPs produced during glycolysis, the transition reaction, the Krebs cycle, and the oxidative-phosphorylation process.

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Relating to oxidative phosphorylation (electron transport chain + chemiosmosis): relate facilitated diffusion of H+ ions through the ATP synthase protein channel to the making of ATP.

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Relating to oxidative phosphorylation (electron transport chain + chemiosmosis): relate the electrochemical gradient to the facilitated diffusion of H+ ions across a membrane.

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The Citric Acid Cycle also known as the Krebs cycle serves what purpose?

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What effect would an absence of O2 have on the process shown in figure 9.15?

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Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration? (eText Concept 9.1) oxidation of glucose to pyruvate; reduction of pyruvate; TCA cycle; oxidative phosphorylation glycolysis; oxidative phosphorylation; TCA cycle; oxidation of pyruvate. oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation oxidation of pyruvate; TCA cycle; oxidation of glucose to pyruvate; oxidative phosphorylation glycolysis; reduction of pyruvate; TCA cycle; oxidative phosphorylation

1. oxidation of glucose to pyruvate; 2. oxidation of pyruvate; 3. oxidation of acetyl-coA; 4. oxidative phosphorylation

What are the 4 major steps of cellular respiration?

1.Glycolysis- (occurs in the cytosol) 2. Pyruvate Oxidation - Formation of Acetyl Co-enzyme A (occurs in the mitochondrion) 3. TCA/Kreb's Cycle/ Citric Acid Cycle 4. Oxidative phosphorylation - Electron Transport Chain and Chemiosmosis - (occurs in the inner membrane of the mitochondrion)

How many ATP are produced by the citric acid cycle for each molecule of glucose?

2

The Citric Acid Cycle

A chemical cycle involving eight steps taht completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidyzing acetyl CoA (derived from pyruvate) to carbon diozide; occcurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; together with pyruvate oxidation, the second majoy stage in cellular respiration.

Redox Reactions

A chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another; short for reduction-oxidation reaction

ATP Synthase

A complex of several membrane proteins that functions in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion (proton) concentration gradient to make ATP. ATP synthases are found in the inner mitochondrial membranes of eukaryotic cells and in the plasma membranes of prokaryotes.

As it pertains to cellular respiration, distinguish between the site of cellular respiration in prokaryotic cells and in eukaryotic cells.

ATP synthases are found in the inner mitochondrial membranes of eukaryotic cells and in the plasma membranes of prokaryotes.

Acetyl CoA

Acetyl coenzyme A; the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.

Chemiosmosis

An energy coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work; such as the synthesis of ATP. Under aerobic conditions, most ATP synthesis in cells occurs by chemiosmosis.

Cytochromes

An iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplasts of eukaryotic cells and the plasma membranes of prokaryotic cells

Facultative Anaerobes

An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present

Obligate Anaerobes

An organism that only carries out fermentation or anaerobic respiration. cannot use oxygen and may be poisoned by it

Compare and contrast aerobic and anaerobic respiration

Both processes include glycolysis, the citric acid cycle, and oxidated phosphorylation. In aerobic respiration the final electron acceptor is molecular oxygen O2; in anaerobic respiration the final electron Accceptor is a different substance.

What is the correct general equation for cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy

What processes in your cells produce the CO2 that you exhale

CO2 is released from the pyruvate that is the end product of glycoloysis, and CO2 is also released during the citric acid cycle

Aerobic Respiration

Catabolic pathway in which oxygen is consumed as a reactant along with the organic fuel

Explain concept 9.1: Catabolic pathways yield energy by oxidizing organic fuels

Catabolic pathways are a set of metabolic pathways that breaks down molecules into smaller units to release energy

Which process or processes return carbon to the atmosphere?

Cellular Respiration

Which of the following best describes the electron transport chain? (eText Concept 9.4) Acetyl CoA is fully oxidized to CO2. Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle. Electrons are passed from one carrier to another, releasing a little energy at each step. Hydrogen atoms are added to CO2 to make an energy-rich compound. Electrons are pumped across a membrane by active transport.

Electrons are passed from one carrier to another, releasing a little energy at each step.

Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria? (eText Concept 9.4)

Electrons moving down the electron transport chain

The function of cellular respiration is to _____. (eText Concept 9.1) reduce CO2 produce carbohydrates extract CO2 from the atmosphere synthesize macromolecules from monomers extract usable energy from glucose

Extract usable energy from glucose. The most prevalent and efficient catabolic pathway is cellular respiration, in which oxygen is consumed as a reactant, along with the organic fuel (frequently glucose).

A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of carbohydrate. Which of the following best explains this observation? (eText Concept 9.6) Fats are better electron donors to oxygen than are sugars. Fats do not form true macromolecules as sugars do. Fats are closely related to lipid molecules, the basic building blocks of cellular membranes. Fats are less soluble in water than sugars. Fats are produced when cells take in more food than they need.

Fats are better electron donors to oxygen than are sugars. Correct. Fats contain more hydrogen and less oxygen than sugars—it is the transfer of electrons from good donors such as hydrogen atoms to good acceptors such as oxygen that provides the energy in respiration.

How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen? (eText Concept 9.3)

Four There is a net gain of two ATP from glycolysis and one per each molecule of acetyl CoA oxidized in the citric acid cycle for a total of four per glucose.

What is the correct basic equation for cellular respiration?

Glucose + 6 Oxygen leads to 6 Carbon Dioxide +6 Water + 1 ATP

Which of the part of the cellular respiration process takes place in the cytosol of a eukaryotic cell?

Glycolysis

Lactic Acid Fermentation

Glycolysis followed by the reduction of pyruvate to lactate, regenerating NAD+ with no release of of carbon dioxide.

Alcohol Fermentation

Glycolysis followed by the reduction pyruvate to ethyl alcohol, regenerating NAD+ and releasing carbon dioxide

Where do the reactions of glycolysis occur in a eukaryotic cell? (eText Concept 9.1) the cytosol across the inner membrane of the mitochondrion the matrix of the mitochondrion in the intermembrane space of the mitochondrion the inner membrane of the mitochondrion

Glycolysis occurs in the cytosol.

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

H+ concentration across the membrane holding ATP synthase.

In cellular respiration, where does Glycolysis occur?

In the cytosol

Cellular Respiration

Includes both aerobic and anaerobic processes

Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one glucose molecule. What happens to the rest of the energy in glucose? (eText Concept 9.1) It is converted to starch. It is converted to heat. It is released as carbon dioxide and water It is stored as fat. It is used to make water from hydrogen ions and oxygen.

It is converted to heat.

A molecule becomes more oxidized when it _

Loses an electron. During oxidation, an electron is removed.

Which part of a eukaryotic cell is involved in cellular respiration?

Mitochondria

Describe the difference between the two processes in cellular respiration that produce ATP: oxidative phosphorylation and substrate-level phosphorylation

Most of the ATP produced in cellular respiration come from oxidative phosphorylation, in which the energy released from redox reactions in an electron transport chain is used to produce ATP. In substrate level phosphorylation, an enzyme dirctly transfers a phosphate group to ADP fro an intermediate substrate. All ATP production in glycolysis occurs by substrate-level phosphorylation, this form of ATP production also occurs at one step in the citric acid cycle.

In glycolysis in the absence of oxygen, cells need a way to regenerate which compound? (eText Concept 9.5)

NAD+

During the redox reaction in glycolysis, which molecule acts as the oxidizing agent? Which molecule acts as the reducing agent?

NAD+ acts as the oxidizing agent in step 6, accepting electrons from glyceraldehyde 3-phosphate, which thus acts as the reducing agent

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of _____.

NADH The citric acid cycle produces three NADH per turn of the cycle.

In the Cellular Respiration Process, which coenzymes is an electron carrier?

NADH and FADH2

Name the molecules that conserve most of the energy from the citric acid cycle's redox reactions. How is this energy converted to a form that can be used to make ATP?

NADH and FADH2; they will donate electrons to the electron transport chain

In a eukaryotic cell, most of the ATP derived from glucose during cellular respiration is produced by ...

The Electron Transport Chain

NAD+

Nicotinamide adenine dinucleotide, a coenzyme that cycles easily between oxidized (NAD+) and reduced (NADH) states, thus acting as an electron carrier.

OIL RIG

Oxidation is Loss of Electrons (OIL) RIG (Reduction is a Gain of Electrons)

Glucose and _______ are consumed during cellular respiration

Oxygen

Reduction

The complete or partial addition of electrons to a substance involved in a redox reaction

Fermentation

Partial degradation of sugars or other organic fuel that occurs without the use of oxygen

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs? (eText Concept 9.3) Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH. Pyruvate is reduced and decarboxylated, and the resulting electrons oxidize an NAD+ to an NADH Pyruvate is oxidized and decarboxylated, and the resulting electrons are donated to NADH to produce NAD+. Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a carbon dioxide from the environment, and its reduction by NADH. Pyruvate is ionized directly to acetyl-coA.

Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.

Oxidation

The complete or partial loss of electrons from a substance involved in a redox reaction

Reducing Agent

The electron donor in a redox reaction

Oxidizing Agent

The electron receptor in a redox reaction

In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?

The Mitochondrion

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes? (eText Concept 9.3) substrate-level phosphorylation the citric acid cycle glycolysis anabolic pathways oxidative phosphorylation

The citric acid cycle Both NADH and FADH2 are produced during the citric acid cycle.

If significant amounts of materials are removed from the citric acid cycle to produce amino acids for protein synthesis, which of the following will result? (eText Concept 9.6) Less ATP will be produced by the cell. Less CO2 will be produced by the cell. The four-carbon compound that combines with acetyl CoA will have to be made by some other process. The first two answers are correct. The first three answers are correct.

The first three answers are correct.

If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result? (eText Concept 9.5) The muscle cells will have more trouble making enough ATP to meet their energy requirements. The cells will not be able to carry out oxidative phosphorylation. The cells will consume glucose at an increased rate. Only the first two answers are correct. The first three answers are correct.

The first three answers are correct. The muscle cells will have more trouble making enough ATP to meet their energy requirements. The cells will not be able to carry out oxidative phosphorylation. The cells will consume glucose at an increased rate.

What is the major (but not the only) energy accomplishment of the citric acid cycle? (eText Concept 9.3)

The formation of NADH and FADH2 Each turn of the citric acid cycle releases carbon dioxide, forms one ATP by oxidative phosphorylation, and passes electrons to three NAD+ and one FAD.

Why is the citric acid cycle called a cycle? (eText Concept 9.3)

The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle.

Where do the reactions of the citric acid cycle occur in eukaryotic cells?

The matrix of the mitochondrion The citric acid cycle, which takes place in the mitochondrial matrix, completes the degradation of glucose.

What is the source of energy for the formation of ATP and NADH in glycolysis?

The oxidation of the three carbon sugar glyceraldehyde 3-phosphate, yields energy. In this oxidation, electrons and H+ are transferred to NAD+, forming NADH, and a phosphate group is attached to the oxidized substrate. ATP is then formed b y substrate level phosphorylation when this phosphate group is transferred to ADP

Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that _____. (eText Concept 9.1) oxygen gas contains a double bond oxygen acts as the final electron acceptor in cellular respiration the oxygen atom is very electronegative oxygen is so abundant in the atmosphere oxygen gas is composed of two atoms of oxygen

The oxygen atom is very electronegative. The high electronegativity of the oxygen atom is the reason that oxygen is such a good oxidizing agent (why it can oxidize so many compounds).

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? ATP synthase pumps protons by active transport. The pH of the matrix increases.

The pH of the matrix increases.

Protonmotive Force

The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions (H+) across a biological membrane during chemiosmosis.

Oxidative Phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration

How would you describe the citric acid cycle

This process produces some ATP and carbon dioxide in the mitochondrion.

How would you describe glycolysis?

This process splits glucose in half and produces 2 ATPs for each glucose.

How would you describe the electron transport chain?

This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration

A small amount of ATP is made in glycolysis by which of the following processes? (eText Concept 9.1) transfer of electrons and hydrogen atoms to NAD+ transport of electrons through a series of carriers attachment of a free inorganic phosphate (Pi) group to ADP to make ATP transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation harnessing energy from the sun

Transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation

How much does a single glucose molecule produce in glycoloysis alone?

a single glucose molecule in glycolysis produces a total of: 2 molecules of pyruvic acid, 2 molecules of ATP, 2 molecules of NADH and 2 molecules of water

Word Roots: aero-

air (aerobic: chemical reaction using oxygen)

When protein molecules are used as fuel for cellular respiration, _____ are produced as waste. (eText Concept 9.6) ethanol and CO2 molecules of lactate fatty acids amino groups sugar molecules

amino groups The amino group is a residual product of amino acid catabolism.

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes? (eText Concept 9.4) at the end of glycolysis to oxidize pyruvate at the end of the electron transport chain to accept electrons and form H2O between glycolysis and the citric acid cycle to split a carbon from pyruvate, producing CO2 as a source of O2 in every reaction that produces CO2 at the end of the citric acid cycle to regenerate citric acid

at the end of the electron transport chain to accept electrons and form H2O

Word Roots: chemi-

chemical (chemiosmosis: the production of ATP using the energy of hydrogen ion gradients across membranes to phosphorylate ADP)

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step _____. (eText Concept 9.5)

enables the cell to recycle the reduced NADH to oxidized NAD+

In the overall process of glycolysis and cellular respiration, _____ is oxidized and _____ is reduced.

glucose ... oxygen In cellular respiration, electrons and hydrogen are removed from glucose and added to oxygen.

During the redox reaction in glycolysis, Which molecule acts as the reducing agent?

glyceraldehyde 3-phosphate, which acts as the reducing agent

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

glycolysis

Of the metabolic pathways listed below, which is the only pathway found in all organisms? (eText Concept 9.5) the electron transport chain cellular respiration fermentation the citric acid cycle glycolysis

glycolysis Ancient prokaryotes probably used glycolysis to make ATP long before oxygen was present in Earth's atmosphere. Glycolysis is the most widespread metabolic pathway.

What is the correct sequence of steps as energy is extracted from glucose during cellular respiration.

glycolysis → acetyl CoA → citric acid cycle → electron transport chain

During respiration in eukaryotic cells, the electron transport chain is located in or on the _____. (eText Concept 9.4)

inner membrane of the mitochondrion

Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds? (eText Concept 9.5)

lactate. In humans, muscle cells switch to lactate fermentation after becoming anaerobic.

Word Roots: an-

not (anaerobic: chemical reaction not using oxygen)

During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction? (eText Concept 9.1) carbon dioxide oxygen water glucose both glucose and carbon dioxide

oxygen

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

oxygen.

In mitochondria, exergonic redox reactions

provide the energy that establishes the proton gradient.

In brewing beer, maltose (a disaccharide of glucose) is _____.

the substrate for alcoholic fermentation

In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle? (eText Concept 9.3)

two ATP, six NADH, two FADH2