Unit 3 - Part 2 Cellular Respiration - Glycolysis and Fermentation

Which of the following correctly describes some aspect of substrate-level phosphorylation in glycolysis? - A bond must be broken between an organic molecule and phosphate before ATP can form. - An enzyme is required in order for the reaction to occur. - One of the substrates is a molecule derived from the breakdown of glucose. - The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP. - The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions.

- A bond must be broken between an organic molecule and phosphate before ATP can form. - An enzyme is required in order for the reaction to occur. - One of the substrates is a molecule derived from the breakdown of glucose. In substrate-level phosphorylation, an enzyme transfers a phosphate group from one molecule (an intermediate in the breakdown of glucose to pyruvate) to ADP to form ATP. This is very different from the mechanism of ATP synthesis that takes place in oxidative phosphorylation.

Walk me through the process of cellular respiration

1 - begins with glycolysis in the cytosol 2 - Pyruvate, the product of glycolysis, then enters the mitochondrial matrix, crossing both the outer and inner membranes. 3 - Both acetyl CoA formation and the citric acid cycle take place in the matrix. 4 - The NADH and FADH2 produced during the first three stages release their electrons to the electron transport chain of oxidative phosphorylation at the inner mitochondrial membrane. 5 - The inner membrane provides the barrier that creates an H+ gradient during electron transport, which is used for ATP synthesis.

In glycolysis there is a net gain of _____ ATP.

2 It takes 2 ATP to produce 4 ATP.

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?

Carbon Dioxide: Two molecules are formed as pyruvate is converted to acetyl CoA, and four molecules are formed during the Krebs cycle.

Which stage of glucose metabolism produces the most ATP?

Electron transport and chemiosmosis (oxidative phosphorylation) can yield around 26 molecules of ATP.

Which of these is NOT a product of glycolysis? pyruvate FADH2 ATP NADH

FADH2 (It is a product of the citric acid cycle.)

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?

Fermentation is an alternate pathway used when oxygen levels are low.

In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced?

Glucose is consumed, and carbon dioxide is produced. The carbon in glucose is oxidized to carbon dioxide during cellular respiration.

In the process of cellular respiration, what is consumed, and what is produced?

Glucose is consumed, and carbon dioxide is produced. The carbon in glucose is oxidized to carbon dioxide during cellular respiration.

Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?

Glucose is used to produce high-energy ATP in a cell.

The by-product of aerobic respiration is __________.

H2O

A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose?

It is stored in NADH and FADH2 The electrons obtained from the oxidation of glucose are temporarily stored in NADH and FADH2. The energy derived from the oxidation of NADH and FADH2 is used to drive the electron transport chain and chemiosmotic synthesis of ATP.

In glycolysis, which molecule picks up the electrons released by the oxidation of glucose?

NAD+

_______ is the compound that functions as the electron acceptor in glycolysis.

NAD+

The reduced form of the electron acceptor in glycolysis is _______.

NADH

Which of the following statements about the electron transport chain is true? Water is the last electron acceptor. The electron transport chain is the first step in cellular respiration. NADH and FADH2 donate their electrons to the chain. Electrons gain energy as they move down the chain.

NADH and FADH2 donate their electrons to the chain 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.

From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. CO2, ADP, P_i, ATP, glucose, NADH, NAD+, coenzyme A, acetyl coA, O2, and pyruvate

Net Inputs: Glucose, NAD+, ADP Net Outputs: NADH, Pyruvate, ATP No Net Inputs or Outputs: O2, CO2, P_i, acetyl coA, and coenzyme A

From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation. CO2, ADP, P_i, ATP, glucose, NADH, NAD+, coenzyme A, acetyl coA, O2, water, and pyruvate

Net Inputs: NADH, ADP, O2 Net Outputs: NAD+, ATP, Water No Net Inputs or Outputs: glucose, pyruvate, acetyl coA, coenzyme A, CO2

From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of the citric acid cycle. CO2, ADP, P_i, ATP, glucose, NADH, NAD+, coenzyme A, acetyl coA, O2, and pyruvate

Net Inputs: acetyl coA, ADP, NAD+ Net Outputs: ATP, NADH, CO2, coenzyme A No Net Inputs or Outputs: pyruvate, O2, glucose

From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of acetyl CoA formation. CO2, ADP, P_i, ATP, glucose, NADH, NAD+, coenzyme A, acetyl coA, O2, and pyruvate

Net Inputs: coenzyme A, pyruvate, NAD+ Net Outputs: acetyl coA, NADH, CO2 No Net Inputs or Outputs: ADP, ATP, glucose

What is the role of oxygen in cellular respiration?

Oxygen accepts high-energy electrons after they are stripped from glucose.

Which of the following are the reactants and which are the products? pyruvate, lactate, NAD+, NADH

Reactants: pyruvate and NADH Products: lactate and NAD+

In glycolysis, what starts the process of glucose oxidation? FADH2 hexokinase ATP NADPH ADP

Some ATP energy is used to start the process of glucose oxidation.

Which statement about the citric acid cycle is correct? -The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. -The citric acid cycle oxidizes glucose to carbon dioxide. -The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. -The oxidation of compounds by the citric acid cycle requires molecular oxygen. -The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain.

The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.

True; 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.

True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.

True; 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.

How many NADH are produced by glycolysis?

Two NADH molecules are produced by glycolysis.

Is the NADH produced in glycolysis used in any other reactions of cellular respiration where ATP is produced?

Yes, NADH is an input to oxidative phosphorylation, where more ATP is produced. NADH is produced by glycolysis, acetyl CoA formation, and the citric acid cycle. All of this NADH is used as an input to oxidative phosphorylation to drive the synthesis of most of the cell's ATP.

acetyl CoA

aerobic oxidation

Cellular respiration accomplishes two major processes: (1) it breaks glucose down into smaller molecules, and (2) it harvests the chemical energy released and stores it in ATP molecules. By the end of _____, the breakdown of glucose is complete; most ATP molecules are produced during _____.

citric acid cycle . . . electron transport chain

Where does glycolysis occur?

cytosol

lactate

fermentation in human muscle

ethanol

fermentation in yeast and bacteria

In glycolysis, the carbon-containing compound that functions as the electron donor is _________.

glucose

Describe the net reaction of glycolysis

glucose (the electron donor) is oxidized to pyruvate. The electrons removed from glucose are transferred to the electron acceptor, NAD+, creating NADH.

Which step of the cellular respiration pathway can take place in the absence of oxygen?

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.

Where does oxidative phosphorylation occur?

inner mitochondrial membrane

In muscle cells, fermentation produces _____.

lactate and NAD+

Where does Acetyl CoA formation occur?

mitochondrial matrix

Where does the citric acid cycle occur?

mitochondrial matrix

When a compound donates (loses) electrons, that compound becomes _________. Such a compound is often referred to as an electron donor.

oxidized

When pyruvate is _____ to acetyl CoA, NAD+ is reduced to NADH.

oxidized

Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called ________.

pyruvate

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

pyruvate

What occurs in acetyl CoA formation?

pyruvate (a product of glycolysis) is oxidized to acetyl CoA, with the reduction of NAD+ to NADH and the release of one molecule of CO2.

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?

pyruvate, ATP, and NADH 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.

pyruvate...NADH; The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

When a compound accepts (gains) electrons, that compound becomes _________. Such a compound is often referred to as an electron acceptor.

reduced

In glycolysis, ATP molecules are produced by _____.

substrate-level phosphorylation; A phosphate group is transferred from glyceraldehyde phosphate to ADP.

What occurs in oxidative phosphorylation?

the NADH and FADH2 produced by the first three stages of cellular respiration are oxidized in the electron transport chain, reducing O2 to water and recycling NAD+ and FAD back to the first three stages of cellular respiration. The electron transport reactions supply the energy to drive most of a cell's ATP production.

Which part(s) of cellular respiration take(s) place in the mitochondria?

the citric acid cycle and the electron transport chain

What occurs in glycolysis?

the six-carbon sugar glucose is converted to two molecules of pyruvate (three carbons each), with the net production of 2 ATP and 2 NADH per glucose molecule. There is no O2 uptake or CO2 release in glycolysis.

What occurs in the citric acid cycle?

the two carbons from the acetyl group of acetyl CoA are oxidized to two molecules of CO2, while several molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. In addition, one molecule of ATP is produced.

NADH and FADH 2 are important in cellular respiration because they deliver high-energy electrons to the electron transport system. Electron transport produces _____ ATP molecule(s) per NADH molecule and _____ ATP molecules(s) per FADH 2 molecule.

three . . . two

Which of the following is the most important result of the process of cellular respiration in biological systems?

transforming the energy in glucose and related molecules in a chemical form that cells can use for work

Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? -producing complex molecules from chemical building blocks -breaking down ATP, so that ADP and P can be reused -the breakdown of glucose to carbon dioxide and water -catabolism of sugars and related compounds -transforming the energy in glucose and related molecules in a chemical form that cells can use for work

transforming the energy in glucose and related molecules in a chemical form that cells can use for work; energy made available during cellular respiration is coupled to a production of ATP, the basic energy currency that cells use for work.

In electron transport, high-energy electrons "fall" to oxygen through a series of reactions. The energy released is used to _____.

transport protons into the intermembrane space of the mitochondria, where they become concentrated. They then flow back out into the the inner compartment (matrix) of the mitochondria. On the way back, protons turn ATP synthase turbines and produce ATP.