Cellular Respiration: Glycolysis

In glycolysis, what starts the process of glucose oxidation?

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

What are the by-products of cellular respiration?

Carbon dioxide and water

What is the site of cellular respiration?

Mitchondria

In glycolysis, ATP molecules are produced by ______.

Substrate-level phosphorylation (A phosphate group is transferred from glyceraldehyde phosphate to ADP

Redox (oxidation-reduction reactions in glycolysis In glycolysis, as in all the stages of cellular respiration, the transfer of electrons from electron donors to electron acceptors plays a critical role in the overall conversion of the energy in foods to energy in ATP. These reactions involving electron transfers are known as oxidation-reduction, or redox, reactions. Drag the words on the left to the appropriate blanks on the right to complete the sentences.

1. When a compound donates (loses) electrons, that compound becomes [oxidized]. Such a compound is often referred to as an electron donor. 2. When a compound accepts (gains) electrons, that compound becomes [reduced]. Such a compound is often referred to as an electron acceptor. 3. In glycolysis, the carbon-containing compound that functions as the electron donor is [glucose]. 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called [pyruvate] 5. [NAD+] is the compound that functions as the electron acceptor in glycolysis 6. The reduced form of the electron acceptor in glycolysis is [NADH]

In glycolysis there is a net gain of ______ ATP.

2 (It takes 2 ATP to produce 4 ATP)

How many NADH are produced by glycolysis?

2 (Two NADH molecules are produced by glycolysis)

Which of these is an example of negative feedback? - As a blood clot begins to form, the process of its formation gets faster and faster - After you eat, gulag stimulates an increase in blood sugar levels - After you eat, insulin stimulates the lowering of blood sugar levels - The digestive enzyme pepsinogen is converted to pepsin by the action of hydrochloric acid; pepsin itself can then convert pepsinogen into pepsin - Once labor begins, contractions increase in frequency and intensity

After you eat, insulin stimulates the lowering of blood sugar levels (Eating raises blood sugar levels so insulin stimulates the lowering of blood sugar level)

Which answer best explains why aerobic respiration produces more ATP per mole of glucose than either anaerobic respiration or fermentation?

Among known electron acceptors, O2 is most electronegative. (Oxygen's high electronegativity means that there is a larger potential energy drop in aerobic respiration than in either anaerobic respiration or fermentation)

Canine phosphofructokinase (PFK) deficiency afflicts springer spaniels, affecting an estimated 10% of the breed. PRK is the glycolytic enzyme that phosphorylates fructose-1-phosphate and catalyzes the committed step in glycolysis. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is ______.

An intolerance for exercise

Cellular locations of the four stages of cellular respiration Each of the four stages of cellular respiration occurs in a specific location inside or outside the mitochondria. These locations permit precise regulation and partitioning of cellular resources to optimize the utilization of cellular energy. Diagram of a mitochondrion showing the cytosol, intermembrane space, mitochondrial matrix, inner mitochondrial membrane, and outer mitochondrial membrane Match each stage of cellular respiration with the cellular location in which it occurs. Labels may be used once, more than once, or not at all.

Cellular respiration begins with glycolysis in the cytosol. Pyruvate, the product of glycolysis, then enters the mitochondrial matrix, crossing both the outer and inner membranes. Both acetyl CoA formation and the citric acid cycle take place in the matrix. 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. The inner membrane provides the barrier that creates an H+ gradient during electron transport, which is used for ATP synthesis.

ATP synthesis in glycolysis: substrate-level phosphorylation The ATP that is generated in glycolysis is produced by substrate-level phosphorylation, a very different mechanism than the one used to produce ATP during oxidative phosphorylation. Phosphorylation reactions involve the addition of a phosphate group to another molecule. Sort the statements into the appropriate bin depending on whether or not they correctly describe some aspect of substrate-level phosphorylation in glycolysis.

Correct statements: - One of the substrates is a molecule derived from the breakdown of glucose - 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 Incorrect statement: - The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions - The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP (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)

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

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

What is released into the atmosphere during photosynthesis?

Glucose and oxygen

In the phosphofructokinase molecule shown in the figure above, the active site has a much higher affinity for ATP than the regulatory site does. Which answer best summarizes what the consequences would be if the regulatory site had a much higher affinity for ATP than the active site did?

Glucose oxidation would be inhibited even if ATP were scarce in the cell (Because the regulatory site has a much higher affinity for ATP, more enzyme molecules would be inhibited at low ATP concentrations

What process occurs in the cytosol?

Glycolysis

Glycolysis is active when cellular energy levels are ______; the regulatory enzyme, phosphofructokinase, is ______ by ATP

Low; inhibited

The high-energy electron carrier that is reduced during glycolysis, pyruvate processing, and the citric acid cycle, and which carries electrons to the electron transport system, is ______.

NADH

Oxidative Phosphorylation In the last stage of cellular respiration, oxidative phosphorylation, all of the reduced electron carriers produced in the previous stages are oxidized by oxygen via the electron transport chain. The energy from this oxidation is stored in a form that is used by most other energy-requiring reactions in cells. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation. Drag each compound to the appropriate bin. If a compound is not involved in oxidative phosphorylation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.)

Net Input: - ADP - O2 - NADH Net Output: - ATP - water - NAD+ Not Input or Output: - CO2 - acetyl CoA - coenzyme A - pyruvate - glucose (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 bak to the first three stages of cellular respiration. The electron transport reactions supply the energy to drive most of a cell's ATP production)

Citric Acid Cycle In the citric acid cycle (also known as the Krebs cycle), acetyl CoA is completely oxidized. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of the citric acid cycle. Drag each compound to the appropriate bin. If a compound is not involved in the citric acid cycle, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of the citric acid cycle are included.)

Net Input: - acetyl CoA - NAD+ - ADP Net Output: - coenzyme A - NADH - ATP - CO2 Not Input or Output: - glucose - pyruvate - O2 (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.

Glycolysis From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. Drag each compound to the appropriate bin. If the compound is not involved in glycolysis, drag it to the "not input or output" bin.

Net Input: - glucose - ADP - NAD+ Net Output: - pyruvate - ATP - NADH Not Input or Output - O2 - CO2 - Acetyl CoA - Coenzyme A (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)

Acetyl CoA Formation In acetyl CoA formation, the carbon-containing compound from glycolysis is oxidized to produce acetyl CoA. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of acetyl CoA formation. Drag each compound to the appropriate bin. If a compound is not involved in acetyl CoA formation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of acetyl CoA formation are included.)

Net Input: - pyruvate - NAD+ - coenzyme A Net Output: - CO2 - NADH - Acetyl CoA Not Input or Output: - O2 - Glucose - ATP - ADP (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.

What is the final electron acceptor of cellular respiration?

Oxygen

______ is the three-carbon sugar that is produced as an end product of glycolysis.

Pyruvate

Energy from glycolysis 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

Two ATP molecules are expended in the energy investment phase of glycolysis. Why is this energy needed to begin the process of glucose catabolism?

Some energy must be invested to make the glucose molecule unstable and begin the process of catabolism.

What process occurs in the electrons carried by electrons carried via NADH an FADH2?

The citric acid cycle