Cellular Respiration Overview

Questions and Answers

What completes the energy-yielding oxidation of organic molecules?

the citric acid cycle

What does Glycolysis produce?

2 ATP, 2 pyruvate, 2 H2O, and 2 NADH + 2 H+

What may enter the mitochondria for respiration?

pyruvate and NADH

What consists of an intermembrane space between the two membranes to house H+?

a mitochondrion Signup and view all the answers

What is housed that has been pumped across the inner membrane during the redox reactions of the electron transport chain?

H+ Signup and view all the answers

What is a chemiosmotic mechanism in which a proton motive force drives protons through ATP synthases located in the membrane?

oxidative phosphorylation Signup and view all the answers

What are oxidation-reduction reactions?

redox reactions Signup and view all the answers

What reactions involve the partial or complete transfer of one or more electrons from one reactant to another?

redox reactions Signup and view all the answers

What is the loss of electrons from one substance?

oxidation Signup and view all the answers

What is the addition of electrons to another substance?

reduction Signup and view all the answers

What is a synonym for an electron donor?

reducing agent Signup and view all the answers

The substance that loses electrons becomes oxidized and acts as a what to the substance that gains electrons?

reducing agent Signup and view all the answers

By gaining electrons, a substance acts as a what and becomes reduced?

oxidizing agent Signup and view all the answers

What is a synonym for an electron acceptor?

oxidizing agent Signup and view all the answers

Chemical energy is released in a redox reaction that relocates electrons closer to what?

oxygen Signup and view all the answers

What are removed by enzymes called dehydrogenases during the oxidation of glucose?

two hydrogen atoms Signup and view all the answers

The two electrons and one proton are passed to what coenzyme, reducing it to NADH?

NAD+ Signup and view all the answers

Energy from respiration is slowly released in a series of small steps as electrons are passed from NADH down what?

an electron transport chain Signup and view all the answers

What is located in the mitochondrial matrix?

the citric acid cycle Signup and view all the answers

The citric acid cycle converts a derivative of what into what?

pyruvate into carbon dioxide Signup and view all the answers

What enzymes transfer electrons to NAD+?

dehydrogenase enzymes Signup and view all the answers

What passes electrons to the electron transport chain?

NADH Signup and view all the answers

The energy released through a chain of redox reactions is used to synthesize ATP by what?

oxidative phosphorylation Signup and view all the answers

What are the phases of Glycolysis?

the energy-investment phase and the energy pay-off phase Signup and view all the answers

What transfer phosphate groups?

kinases Signup and view all the answers

What oxidizes glyceraldehyde-3-phosphate?

a dehydrogenase Signup and view all the answers

What enzyme reduces NAD+?

a dehydrogenase Signup and view all the answers

What is actively transported into the mitochondrion?

pyruvate Signup and view all the answers

The remaining two-carbon group is oxidized to form what with the accompanying reduction of what to what?

acetate with the reduction of NAD+ to NADH Signup and view all the answers

What does coenzyme A form when it's attached to the acetate by an unstable bond?

acetyl CoA Signup and view all the answers

During the citric acid cycle, citrate is progressively decomposed back to what?

oxaloacetate Signup and view all the answers

For each turn of the citric acid cycle, what enters in the reduced form from acetyl CoA?

two carbon Signup and view all the answers

During each turn of the citric acid cycle, how many NADH and how many FADH2 are formed?

three NADH and one FADH2 Signup and view all the answers

How many ATP are made by substrate-level phosphorylation?

one Signup and view all the answers

There are how many turns of the citric acid cycle for each glucose molecule oxidized?

two Signup and view all the answers

What enzyme phosphorylates glucose?

hexokinase Signup and view all the answers

What turns glucose-6-phosphate into fructose-6-phosphate?

phosphoglucoisomerase Signup and view all the answers

What bonds with Acetyl CoA to create a product?

oxaloacetate Signup and view all the answers

Acetyl CoA creates what product?

Citrate Signup and view all the answers

What is a chain of proteins that will accept NADH and FADH2?

the cytochrome Signup and view all the answers

Where do the protons come from on the electron transport chain?

NADH Signup and view all the answers

What are embedded in the cristae of the inner mitochondrial membrane?

electron transport chains Signup and view all the answers

Most components of the electron transport chain are proteins with what?

tightly bound, nonprotein prosthetic groups Signup and view all the answers

What are proteins with an iron-containing heme group?

cytochromes Signup and view all the answers

After the transfer of electrons, electrons pass down a series of molecules called what?

cytochromes Signup and view all the answers

What passes electrons to oxygen?

the last cytochrome Signup and view all the answers

What adds its electrons to the chain at a lower energy chain?

FADH2 Signup and view all the answers

What is a protein complex embedded in the inner membrane?

ATP synthase Signup and view all the answers

What uses the energy of a proton (H+) gradient to make ATP?

ATP synthase Signup and view all the answers

What creates the proton gradient?

the electron transport chain Signup and view all the answers

What reactions produce the H+ gradient that drives the production of ATP in mitochondria?

exergonic redox reactions Signup and view all the answers

Prokaryotes use H+ gradients generated across their plasma membranes to what?

transport molecules, make ATP, and rotate flagella Signup and view all the answers

Fermentation is the anaerobic catabolism of organic nutrients to generate ATP by what?

substrate-level phosphorylation Signup and view all the answers

Both fermentation and respiration use what as the oxidizing agent to convert glucose and other organic fuels to pyruvate?

glycolysis with NAD+ Signup and view all the answers

To oxidize NADH back to NAD+, fermentation uses what as the final electron acceptor?

pyruvate or acetaldehyde Signup and view all the answers

What anaerobes can make ATP by fermentation or respiration, depending upon the availability of oxygen?

facultative anaerobes Signup and view all the answers

What can all be used by cellular respiration to make ATP?

fats, proteins, and carbohydrates Signup and view all the answers

What are digested into amino acids, which then deaminated, and can enter into respiration at several sites?

proteins Signup and view all the answers

What is yielded by the digestion of fats?

glycerol and fatty acids Signup and view all the answers

Fatty acids are broken down by what to acetyl CoA?

beta oxidation Signup and view all the answers

What enzyme turns glucose 6-phosphate into fructose-6-phosphate?

phosphoglucoisomerase Signup and view all the answers

In the first reaction of glycolysis, glucose receives a phosphate group from ATP. This reaction is what?

exergonic Signup and view all the answers

The oxidation of pyruvate to carbon dioxide is called what?

the citric acid cycle Signup and view all the answers

The carbon dioxide that animal cells breathe out is created by what process?

the citric acid cycle Signup and view all the answers

A drug destroys the proton gradient across the inner mitochondrial membrane. If you incubate the isolated mitochondria in a solution of the drug, what wouldn't be made during transport of electrons down the respiratory chain?

ATP Signup and view all the answers

What process includes the electron transport chain and chemiosmosis?

oxidative phosphorylation Signup and view all the answers

What happens when electrons move closer to a more electronegative atom?

energy is released Signup and view all the answers

In cellular respiration, what becomes reduced?

oxygen Signup and view all the answers

What kind of substrate has increased reactivity and is primed to do work?

a substrate that is phosphorylated Signup and view all the answers

Oxidative phosphorylation produces how many ATP per NADH that's oxidized?

three ATP Signup and view all the answers

What process is the energy source for facultative anaerobes under aerobic conditions?

substrate-level phosphorylation Signup and view all the answers

Q and cytochrome c are what?

mobile electron carriers Signup and view all the answers

What causes a multienzyme complex to remove a carboxyl group, transfer electrons to NAD+, and attach to a coenzyme?

the conversion of pyruvate to acetyl CoA Signup and view all the answers

How many molecules of CO2 are generated for each molecule of acetyl CoA introduced into the citric acid cycle?

two Signup and view all the answers

From an energetic viewpoint, what do muscle cells in oxygen deprivation gain from the reduction of pyruvate?

ATP and NAD+ Signup and view all the answers

In alcoholic fermentation, how much alcohol is formed with each molecule of glucose?

two Signup and view all the answers

What makes the most ATP per gram because they are highly reduced compounds?

fats Signup and view all the answers

Fats and proteins can be converted to what of glycolysis or the citric acid cycle?

intermediates Signup and view all the answers

Which enzyme would use NAD+ as a coenzyme?

triose phosphate dehydrogenase Signup and view all the answers

Which compound has the highest free energy and will produce the most ATP when oxidized?

fructose bisphosphate Signup and view all the answers

Acetaldehyde (C2H4O) to ethanol (C2H6O) is what type of reaction?

a reduction reaction Signup and view all the answers

What are the inputs to the oxidation of pyruvate to acetyl CoA?

2 pyruvate, 2 CoA, and 2 NAD+ Signup and view all the answers

What are the outputs of the oxidation of pyruvate to acetyl CoA?

2 acetyl CoA, 2 CO2, and 2 NADH + 2 H+ Signup and view all the answers

What are the inputs of glycolysis?

glucose, 2 ATP, 2 NAD+, 4 ADP + (P)i Signup and view all the answers

What are the inputs of the citric acid cycle?

2 acetyl CoA, 2 ADP + (P)i, 6 NAD+, and 2 FAD Signup and view all the answers

What are the outputs of the citric acid cycle?

2 CoA, 4 CO2, 2 ATP, 6 NADH + 6 H+, and 2 FADH2 Signup and view all the answers

What are the inputs of oxidative phosphorylation?

10 NADH + H+, 2 FADH2, H+ + O2, and 34 ADP + (P)i Signup and view all the answers

What are the outputs of oxidative phosphorylation?

10 NAD+, 2 FAD, H2O, and 34 ATP Signup and view all the answers

What is the input of fermentation (doesn't include the input of glycolysis)?

2 pyruvate and 2 NADH Signup and view all the answers

What are the outputs of fermentation?

2 ATP, 2 NAD+, 2 ethanol and 2 CO2 or 2 lactate Signup and view all the answers

Where is the ATP synthase?

the mitochondrial matrix Signup and view all the answers

Where is the proton gradient?

the intermembrane space Signup and view all the answers

In the I of the electron transport chain, what turns into what?

NADH + H+ to NAD+ Signup and view all the answers

In the IV of the electron transport chain, what turns into what?

2H+ + 1/2 O2 to H2O Signup and view all the answers

How many NADH, FADH2, and ATP is created in Glycolysis?

2 NADH, 0 FADH2, and 2 ATP Signup and view all the answers

How many NADH, FADH2, and ATP is created in Conversion to Acetyl CoA?

2 NADH, 0 FADH2, and 0 ATP Signup and view all the answers

How many NADH, FADH2, and ATP is created in the Citric Acid Cycle?

6 NADH, 2 FADH2, and 2 ATP Signup and view all the answers

How many ATP are generated from one NADH?

3 Signup and view all the answers

How many ATP are generated from one FADH2?

2 Signup and view all the answers

Study Notes

Cellular Respiration Overview

The citric acid cycle completes the energy-yielding oxidation of organic molecules and occurs in the mitochondrial matrix.
Glycolysis produces 2 ATP, 2 pyruvate, 2 H2O, and 2 NADH + 2H+.

Glycolysis and Pyruvate Processing

Pyruvate and NADH enter mitochondria for respiration, where pyruvate is actively transported into the mitochondrial matrix.
Glycolysis occurs in two phases: energy-investment phase and energy pay-off phase.

Key Enzymes and Reactions

Kinases transfer phosphate groups during glycolysis.
Dehydrogenase enzymes oxidize glyceraldehyde-3-phosphate, transferring electrons to NAD+ to form NADH.

Mitochondrial Structure

A mitochondrion consists of an inner membrane housing H+ ions in the intermembrane space.
The electron transport chain is embedded in the cristae of the inner mitochondrial membrane.

Electron Transport Chain and ATP Synthesis

NADH and FADH2 donate electrons to the electron transport chain, which consists of proteins that shuttle electrons.
Electrons move through a series of redox reactions, generating a proton gradient used in oxidative phosphorylation to produce ATP via ATP synthase.

Oxidative Phosphorylation

Oxidative phosphorylation synthesizes ATP and involves chemiosmosis and redox reactions.
Each NADH generates approximately three ATP, whereas FADH2 generates two ATP in the electron transport chain.

Citric Acid Cycle Function

The citric acid cycle converts acetyl CoA into carbon dioxide and transfers high-energy electrons to NADH and FADH2.
For each turn of the cycle, three NADH, one FADH2, and one ATP are produced.

Fermentation Processes

Fermentation produces ATP in anaerobic conditions by converting pyruvate into ethanol or lactate, using NADH as the reducing agent.
Inputs for fermentation include 2 pyruvate and 2 NADH, yielding 2 ATP, 2 NAD+, and either 2 ethanol and 2 CO2 or 2 lactate.

Alternative Fuel Sources

Cellular respiration can utilize fats, proteins, and carbohydrates to generate ATP.
Proteins are deaminated into amino acids, which can enter respiration at various stages, while fats undergo beta oxidation to produce acetyl CoA.

Proton Gradient and Energy Utilization

The proton gradient across the inner membrane powers ATP synthesis and is created along the electron transport chain through exergonic redox reactions.
Mobile electron carriers like Q and cytochrome c play crucial roles in electron transport.

Summary Outputs and Inputs

Glycolysis inputs include glucose, 2 ATP, and 2 NAD+, while outputs are 2 pyruvate, 2 ATP, and 2 NADH.
The citric acid cycle inputs are 2 acetyl CoA, and outputs are 2 ATP, 6 NADH, and 2 FADH2.
Oxidative phosphorylation transforms 10 NADH + H+, 2 FADH2, and 34 ADP + (P)i into 10 NAD+, 2 FAD, water, and 34 ATP.
Each acetyl CoA cycle generates 2 CO2 molecules, contributing to respiratory carbon dioxide output.

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Description

This quiz covers key concepts of cellular respiration, including glycolysis, the citric acid cycle, and the electron transport chain. You will learn about the processes that convert organic molecules into ATP and the roles of various enzymes involved. Test your understanding of mitochondrial structure and function in energy production.