BIOL2050-CHAPTER 7

Cellular Respiration

A process by which living cells obtain energy from organic molecules and release waste products.

**aerobic respiration**

A type of cellular respiration in which O2 is consumed and CO2 is released.

**substrate-level phosphorylation**

A method of synthesizing ATP that occurs when an enzyme directly transfers a phosphate from an organic molecule to ADP.

**chemiosmosis**

A process for making ATP in which energy stored in an ion electrochemical gradient is used to make ATP from ADP and Pi.

**cristae**

Projections of the highly invaginated inner membrane of a mitochondrion.

Glycolysis

A metabolic pathway that breaks down glucose to pyruvate.

Biochemistry

The study of the chemistry of living organisms.

The products of cellular respiration include

water

carbon dioxide

Which of the following molecules are energy intermediates produced during cellular respiration?

ATP

FADH2

NADH

Consider the net equation of cellular respiration. Which of the following molecules would be reactants?

Oxygen

Glucose

What is the main product of cellular respiration?

ATP

four pathways are involved in the breakdown of glucose to carbon dioxide and water

Oxidative phosphorylation

Glycolysis

Breakdown of pyruvate

Citric acid cycle

What process is used to synthesize ATP during glycolysis?

Substrate-level phosphorylation

end products of glycolysis

NADH

ATP

Pyruvate

Glycolysis occurs in the

cytosol

main function of oxidative phosphorylation

Production of ATP

products of the citric acid cycle

1 ATP

3 NADH

1 FADH2

2 Carbon dioxide

In eukaryotic cells, which of the following metabolic pathways occur in the mitochondria?

The breakdown of pyruvate

Oxidative phosphorylation

The citric acid cycle

How many ATP molecules are produced by oxidative phosphorylation for every one molecule of glucose that enters the pathways of cellular respiration?

30-34 ATP

sources of high-energy electrons for oxidative phosphorylation include

FADH2

NADH

In prokaryotes, where does oxidative phosphorylation occur

plasma membrane

statements about invaginations of the inner mitochondrial membrane

Allow for greater ATP production

Are called cristae

Increase surface area

The location of oxidative phosphorylation in prokaryotes is the BLANK membrane and in eukaryotes is the BLANK mitochondrial membrane.

plasma, inner

Glycolysis involves the breakdown of one molecule of glucose into

two molecules of pyruvate

Why are phosphate groups added to glucose during the first phase of glycolysis?

To raise its free energy so that later reactions can be exergonic

During the cleavage stage of glycolysis, a molecule with BLANK carbon atoms is broken into two molecules of BLANK-3-phosphate.

6,glyceraldehyde

Steps of Energy investment phase, Cleavage phase, and Energy liberation phase

Energy investment phase→ ATP is hydrolyzed, and its phosphate groups are attached to glucose.

Cleavage phase→ A six-carbon molecule is converted to two three-carbon molecules.

Energy liberation phase→ ATP and NADH are synthesized.

in glycolysis, **net** yield of ATP per molecule of glucose

2

The net products of glycolysis are Blank

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

third phase of glycolysis

I→ 1,3-bisphosphoglycerate

II→ 3-phosphoglycerate

III→ 2-phosphoglycerate

IV→ Phosphoenolpyruvate

V→ Pyruvate

first phase of glycolysis

A→ Glucose

B→ Glucose-6-phosphate

C→ Fructose-6-phosphate

D→ Fructose-1,6-bisphosphate

Which of the following serve as REACTANTS in the __*net*__ reaction of glycolysis? 

2 NAD+

2 Pi2-

2 ADP2-

The preferential use of glycolysis for ATP production in cancer cells is called the

Warburg effect

During the cleavage phase of glycolysis, fructose-1,6-bisphosphate is split into two different three-carbon molecules

Dihydroxyacetone phosphate

Glyceraldehyde-3-phosphate

factors regulate the rate of glycolysis

Feedback inhibition

Availability of glucose

In eukaryotes, pyruvate dehydrogenase is a BLANK enzyme that BLANK pyruvate.

mitochondrial ; oxidizes

**metabolic cycle**

A biochemical cycle in which particular molecules enter while others leave; the process is cyclical because it involves a series of organic molecules that are regenerated with each turn of the cycle.

Citric Acid Cycle

A cycle that results in the breakdown of carbohydrates to CO2; also known as the Krebs cycle.

Oxidative Phosphorylation

A process during which NADH and FADH2 are oxidized to make more ATP via the phosphorylation of ADP.

Electron Transport Chain

A group of protein complexes and small organic molecules within the inner membranes of mitochondria and chloroplasts and the plasma membrane of prokaryotes. The components accept and donate electrons to each other in a linear manner and produce a H+ electrochemical gradient.

ATP Synthase

An enzyme that utilizes the energy stored in a H+ electrochemical gradient for the synthesis of ATP via chemiosmosis.

In the first reaction of the citric acid cycle, oxaloacetate, which contains BLANK carbons

, is combined with acetyl-CoA, which contains BLANK carbons in its acetyl group,

to produce citric acid, which contains BLANK carbons.

4; 2; 6

What energy intermediates are produced in the citric acid cycle?

GTP

NADH

FADH2

The citric acid cycle consists of how many reactions or steps.

8

What **reactants** are required for the citric acid cycle?

Acetyl-CoA

NAD+

GDP2-

FAD

Amount of Carbons in Acetyl, Oxaloacetate, Citrate, and Carbon Dioxide

Acetyl-CoA→ 2 carbons

Oxaloacetate→ 4 carbons

Citrate→ 6 carbons

Carbon dioxide→ 1 carbon

Each turn of the citric acid cycle produces…

3 NADH and 1 FADH2

What happens to the GTP that is produced in the citric acid cycle?

It is used to make ATP.

What intermediate is regenerated as a result of the reactions of the citric acid cycle?

Oxaloacetate

What are the products of the citric acid cycle?

FADH2

NADH

CO2

CoA—SH

GTP

For one molecule of glucose, the steps preceding oxidative phosphorylation produce a net total of BLANK molecules of CO2,

BLANK molecules of ATP,

BLANK molecules of NADH,

and BLANK molecules of FADH2.

6,4,10,2

The first three stages of the oxidation of one molecule of glucose are glycolysis, pyruvate breakdown, and the citric acid cycle. These collectively produce

6 CO2, 10 NADH, 2 FADH2, and 4 ATP

During oxidative phosphorylation, ATP synthesis is coupled to

the removal of high-energy electrons from NADH and FADH2

The __structural__ components of the electron transport chain include which of the following?

Protein complexes

Small organic molecules

The electron transport chain involves a series of BLANK reactions.

Redox

The iron atoms in the prosthetic groups of the electron transport chain proteins can easily accept and release what?

electrons

Which member of the electron transport chain (ETC) is a small nonpolar organic molecule that can accept and release electrons?

Ubiquinone

In the electron transport chain, electrons are transferred to molecules with increasingly higher

electronegativity

In eukaryotic cells, the electron transport chain is located in the

inner mitochondrial membrane

Many of the proteins of the electron transport chain contain prosthetic groups. These prosthetic groups commonly contain iron, which can easily

accept and release an electron

The electron transport chain is also called the BLANK chain because it consumes oxygen.

respiratory

The electrons donated to the electron transport by FADH2 release BLANK energy than the electrons donated by NADH.

less

The energy released during the transfer of electrons in the electron transport chain is used to

pump protons across the inner mitochondrial membrane

he component of the ETC that receives electrons from NADH BLANK dehydrogenase, while BALNK reductase receives electrons from FADH2.

succinate, nahd

Due to the electron transport chain, the proton concentration is the lowest in the BLANK

mitochondrial matrix

first molecule to receive electrons and ending at the bottom with the final electron acceptor.

Position 1 of 6 NADH dehydrogenase correct toggle button unavailable

NADH dehydrogenase

1\. NADH dehydrogenase

2\. Ubiquinone

3\. Cytochrome b-c1

4\. Cytochrome c

5\. Cytochrome oxidase

6\. Oxygen

During chemiosmosis, energy stored in a proton gradient is

converted to chemical bond energy in ATP

The oxidation of NADH **initially** leads to a high concentration of protons in the BLANK

intermembrane space

As electrons travel through the electron transport chain, BLANK ions are pumped across the cristae into the space between the inner and outer mitochondrial membranes, from a low concentration to a high concentration.

proton

What are the two mechanisms through which high ADP levels stimulate oxidative phosphorylation?

ADP is a substrate used to make ATP.

ADP stimulates cytochrome oxidase.

Which of the following factors regulate oxidative phosphorylation?

The ATP/ADP ratio

The availability of O2

The availability of NADH

When ADP levels are high, oxidative phosphorylation is stimulated because ADP increases the activity of BLANK

cytochrome oxidase

When electrons are transferred to oxygen in the final step of the electron transport chain, a molecule of BLANK is produced.

water

What advantage does integrating protein, carbohydrates, and metabolism have for cells?

The advantage is that cells can use the same enzymes to metabolize different kinds of organic molecules. This saves energy because it would require a lot of energy to make many different enzymes, which are composed of proteins.

**anaerobic**

Refers to an environment that lacks oxygen or a process that occurs in the absence of oxygen, such as anaerobic respiration.

anaerobic Respiration

The breakdown of organic molecules in the absence of oxygen by using a final electron acceptor that is something other than oxygen.

Fermentation

The breakdown of organic molecules to produce energy without any net oxidation of an organic molecule.

Which of the following statements concerning the bacteriorhodopsin experiments that verified chemiosmosis are true?

Both ATP synthase and bacteriorhodopsin were integrated into vesicle membranes.

Bacteriorhodopsin can only generate a proton gradient in the presence of light.

Bacteriorhodopsin is a known proton pump.

Which of these is a light-driven H+ pump found in archaea?

Bacteriorhodopsin

Which type of ATP synthase subunit forms a ring in the membrane?

c

The subunit of ATP synthase that contains a catalytic site where ATP produced is the BLANT subunit.

beta

In the experiments demonstrating that ATP synthase uses a proton gradient to drive ATP synthesis, the proton gradient was generated by BLANK

Bacteriorhodopsin

Bacteriorhodopsin is a proton pump found in some species of archaea. The energy that bacteriorhodopsin uses to pump protons comes from BLANK

light

When protons pass through a site between a *c* subunit and the *a* subunit of ATP synthase, the BLANK subunit of the non-membrane embedded subunits of ATP synthase turns clockwise.

y

Arrange the steps that occur when ATP synthase produces ATP in the correct order.

1. Hydrogen ions flow through a channel in the membrane-bound subunits of ATP synthase.
2. The y subunit of ATP synthase rotates in a clockwise direction.
3. The B subunits of ATP synthase change conformation.
4. ATP is synthesized

The three subunits of the membrane embedded region of ATP synthase are called

a, b, and c

What happens when protons pass through a *c* subunit of ATP synthase?

The γ subunit turns counterclockwise.

Why does using the same pathway for the breakdown of sugars, amino acids, and fats make cellular metabolism more efficient?

The same enzymes can be used.

Yoshida and Kinosita found that when they added ATP to purified ATP synthase

it hydrolyzed ATP and spun in a counterclockwise direction

Which of the following molecules are used as energy sources by living organisms?

Sugars

Fatty acids

Amino acids

Glycerol can enter into glycolysis after it is converted to

glyceraldehyde-3-phosphate

The metabolic intermediate that is shared in common in the utilization of protein, carbohydrates and fat for energy is

acetyl-CoA

How is ATP produced during fermentation?

Substrate-level phosphorylation

What is the outcome of aerobic respiration?

O2 is reduced to H2O

Which of the following statements is true about all forms of anaerobic respiration?

A molecule other than O2 is used as the final electron acceptor.

What type of pathway produces ATP by substrate-level phosphorylation without any net oxidation of organic molecules?

Fermentation

At the end of the electron transport chain, BLANK catalyzes the transfer of electrons to O2.

cytochrome oxidase

Which of the following statements are true regarding the generation of an electrochemical gradient during the conversion of nitrate to nitrite when nitrate serves as a final electron acceptor?

NADH dehydrogenase pumps H+ out of the cytoplasm.

Ubiquinone picks up H+ in the cytoplasm and carries it to the other side of the membrane.

The reduction of nitrate to nitrite consumes H+ in the cytoplasm.

Under anaerobic conditions, glycolysis slows due to the depletion of

NAD+

Under anaerobic conditions, high levels of BLANK may cause the production of free radicals.

NADH