9.1 Cellular Respiration: An Overview Name:

Biology Date: Period:

Lesson Objectives Explain where organisms get the energy they need for life processes. Define cellular respiration. Compare photosynthesis and cellular respiration.

Chemical Energy and Food - Chemical energy is stored in food molecules. Energy is released when chemical bonds in food molecules are broken. Energy is measured in a unit called a calorie, the amount of energy needed to raise the temperature of 1 gram of

water 1Celsius. Fats store more energy per gram than do carbohydrates and proteins.

Overview of Cellular Respiration - Cellular respiration is the process that releases energy from food in the presence of oxygen.

Cellular respiration captures the energy from food in three main stages: glycolysis the Krebs cycle the electron transport chain

Glycolysis does not require oxygen. The Krebs cycle and electron transport chain both require oxygen. Aerobic pathways are processes that require oxygen. Anaerobic pathways are processes that occur without oxygen.

Comparing Photosynthesis and Cellular Respiration The energy in photosynthesis and cellular respiration flows in opposite directions. Their equations are the reverse of each other.

Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses oxygen to release energy from

food.

Chemical Energy and FoodFor Questions 1–4, complete each statement by writing the correct word or words.1. A calorie is a unit of .

2. The Calorie used on food labels is equal to calories.

3. A Calorie is also referred to as a .

4. Cells use the energy stored in chemical bonds of foods to produce compounds that directly power the cell’s activities, such as .

Overview of Cellular RespirationFor Questions 5–10, complete each statement by writing the correct word or words.5. The equation that summarizes cellular respiration, using chemical formulas, is

6. If cellular respiration took place in just one step, most of the would be lost in the form of light and .

7. Cellular respiration begins with a pathway called , which takes place in __________________ of the cell.

8. At the end of glycolysis, about percent of the chemical energy is locked in the bonds of the __________________ molecule.

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9. Cellular respiration continues in the of the cell with the and electron transport chain.

10. The pathways of cellular respiration that require oxygen are said to be . Pathways that do not require oxygen are said to be .

Complete the illustration by adding labels for the three main stages of cellular respiration.

Comparing Photosynthesis and Cellular RespirationFor Questions 11-14, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true. 11. The energy flow in photosynthesis and cellular respiration occurs in the same direction.

12. Photosynthesis deposits energy in Earth’s “savings account” for living organisms.

13. Cellular respiration removes carbon dioxide from the air.

14. Photosynthesis takes place in nearly all life.

Complete the table comparing photosynthesis and cellular respiration.A Comparison of Photosynthesis and Cellular Respiration

Aspect Photosynthesis Cellular Respiration

Function

Location of reactions

Reactants

Products

9.2 The Process of Cellular Respiration Name: 2

Biology Date: Period:

Lesson Objectives Describe what happens during glycolysis. Describe what happens during the Krebs cycle. Explain how high-energy electrons are used by the electron transport chain. Identify how much ATP cellular respiration generates.

Glycolysis - The word glycolysis literally means “sugar-breaking.” The end result is 2 molecules of a 3-carbon molecule called pyruvic acid.

2 ATP molecules are used at the start of glycolysis to get the process started. High-energy electrons are passed to the electron carrier NAD+, forming two molecules of NADH. 4 ATP are synthesized during glycolysis for a net gain of 2 ATP.

The Krebs Cycle The second stage of cellular respiration is the Krebs cycle, which operates only when oxygen is available. The Krebs cycle is a series of energy-extracting reactions.

Pyruvic acid produced by glycolysis enters mitochondria. In the innermost compartment of a mitochondrion, or the matrix, pyruvic acid molecules are broken down into carbon dioxide and acetyl-CoA molecules.

Acetyl-CoA combines with a 4-carbon compound, producing a 6-carbon molecule—citric acid. Energy released by the breaking and rearranging of carbon bonds is captured in ATP, NADH, and FADH2.

The Krebs cycle produces four types of products:1. high-energy electron carriers (NADH and FADH2)2. carbon dioxide3. 2 ATP molecules (per glucose molecule)4. the 4-carbon molecule needed to start the cycle again

Electron Transport and ATP Synthesis The electron transport chain uses the high-energy electrons from glycolysis and the Krebs cycle to convert ADP into ATP.

The electron carriers produced during glycolysis and the Krebs cycle bring high-energy electrons to the electron transport chain. Oxygen is the final electron acceptor.

The passing of electrons through the electron transport chain causes H+ ions to build up in the intermembrane space, making it positively charged relative to the matrix.

The charge difference across the membrane forces H+ ions through channels in enzymes known as ATP synthases. As the ATP synthases spin, a phosphate group is added to ADP, generating ATP.

The Totals Together, glycolysis, the Krebs cycle, and the electron transport chain generate about 36 molecules of ATP per molecule of glucose.

Glycolysis - Complete the diagram by writing on the lines provided the names and numbers of molecules used and produced during glycolysis.

Steps of Cellular Respiration

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Glycolysis Krebs cycle Electron transport chain

Where in cell it occurs

Starting reactants

Ending products

Number of ATP molecules either

produced or gained

Is oxygen required?

1. Why is it an investment for the cell to use two ATP at the beginning of glycolysis?

2. What are two advantages of glycolysis?

The Krebs CycleFor Questions 3-6, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.

3. The pyruvic acid produced in glycolysis enters the chloroplasts if oxygen is present in a cell.

4. In the matrix, pyruvic acid is converted to lactic acid before the Krebs cycle begins.

5. The compound that joins with a 4-carbon molecule in the Krebs cycle is called acetyl-CoA.

6. Carbon dioxide is the only product of the Krebs cycle that is not re-used or used in

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other stages of cellular respiration.Electron Transport and ATP Synthesis - The electron transport chain uses the high-energy electrons produced by the Krebs cycle to move hydrogen ions from one side of the inner membrane to the other. Complete the flowchart about electron transport. Use the terms in the box.

For Questions 7-12, complete each statement by writing the correct word or words.7. In eukaryotes, the electron transport chain is composed of a series of electron carriers located in the

_____________________________of the mitochondrion.

8. In prokaryotes, the electron transport chain is in the _________________________________.

9. __________________ serves as the final electron acceptor of the electron transport chain.

10. _______________ and _______________ pass high-energy electrons to the electron transport chain.

11. The transfer of high-energy electrons down the electron transport chain causes

____________ to be transported across the mitochondrial membrane.

12. ATP synthases produce the force needed to add one to each ADP

molecule by spinning when hydrogen ions flow through them.

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intermembrane electron transport chain ATP synthasepositively inner membrane ATP

The ATP synthase uses the energy from the moving ions to combine ADP and a phosphate, forming high-energy .

H+ ions move through channels of in the inner membrane.

H+ ions build up in the space, making it charged and making the matrix negatively charged.

The energy from the electrons moving down the chain is used to move H+ ions across the .

High-energy electrons from NADH and FADH2 are passed into and along the .

The Totals13. What happens to the carbon dioxide that results from the Krebs cycle?

14. How many ATP molecules per glucose molecule does a cell gain from each of the three stages of cellular

respiration?

15. Besides glucose, what other kinds of molecules can be used to produce ATP in cellular respiration?

16. Why is cellular respiration considered an efficient process?

17. Where does the heat that warms your body come from? Explain your answer.

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9.3 Fermentation Name:

Biology Date: Period:

Lesson Objectives Explain how organisms get energy in the absence of oxygen. Identify the pathways the body uses to release energy during exercise.

Fermentation - releases energy from food molecules by producing ATP without oxygen. Cells convert NADH to the electron carrier NAD+. This allows glycolysis to produce a steady stream of ATP. There are two forms of fermentation. Both start with the reactants pyruvic acid and NADH.

alcoholic fermentation produces ethyl alcohol and carbon dioxideo occurs in yeast and a few other microorganismso produces alcoholic beverages and causes bread dough to rise

lactic acid fermentation produces lactic acido occurs in most organisms, including humanso used to produce beverages such as buttermilk and foods such as cheese, yogurt, and pickles

Energy and Exercise - The body uses different pathways to release energy. For short, quick bursts of energy, the body uses ATP already in muscles as well as ATP made by lactic acid

fermentation. For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of

ATP.

FermentationFor Questions 1–6, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.

1. Glycolysis provides the pyruvic acid molecules used in fermentation.

2. Fermentation allows glycolysis to continue by providing the NADPH needed to accept high-energy electrons.

3. Fermentation is an aerobic process.

4. Fermentation occurs in the mitochondria of cells.

5. Alcoholic fermentation gives off carbon dioxide and is used in making bread.

6. Most organisms perform fermentation using a chemical reaction that converts pyruvic acid to lactic acid.

Compare and contrast fermentation and cellular respiration table. Aspect Fermentation Cellular Respiration

Function

Reactants

Products

Compare and contrast alcoholic fermentation and lactic acid fermentation.

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Lactic Acid Fermentation Alcoholic Fermentation

Reactants

End products

Uses by humans

Label the process that shows alcoholic fermentation. Label the process that shows lactic acid fermentation.

Circle the correct answer. Questions may have more than one correct answer.7. Alcoholic fermentation is used to make which product?

bread cheese yogurt pickles8. What kind of taste do lactic acid bacteria give foods?

sweet salty sour spicy9. What are some milk products made from lactic acid fermentation?

milk sour cream yogurt cheese

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2 Lactic Acid2 Ethyl Alcohol

2 CO2

2 Pyruvic Acid

NAD+ cycles back

NAD+ cycles back

Glucose

CYTOPLASM

Glycolysis

Energy and Exercise10. What causes humans to become lactic acid fermenters?

11. What are three main sources of ATP available for human muscle cells?

12. During a race, how do your muscle cells produce ATP after the store of ATP in muscles is used?

13. Why does a sprinter have an oxygen debt to repay after the race is over?

14. A runner needs more energy for a longer race. How does the body generate the necessary ATP?

15. Why are aerobic forms of exercise so beneficial for weight control?

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16. Compare and contrast the role of fermentation and cellular respiration in the actual production of ATP. In

your response, consider which process produces ATP and which process contributes to its production.

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Compare and contrast Alcoholic and Lactic Acid Fermentation.

For Questions 1–7, match the term with its definition.

Term

1. anaerobic

2. glycolysis

3. Krebs cycle

4. calorie

5. matrix

6. aerobic

7. fermentation

Definition

A. Innermost compartment of a mitochondrion

B. Process that forms either lactic acid or ethyl alcohol when no oxygen is present

C. Stage of cellular respiration that starts with pyruvic acid and produces CO2.

D. Process in which glucose is broken down into two molecules of pyruvic acid

E. “In air”

F. “Without air”

G. Amount of energy needed to raise the temperature of 1 gram of water 1°C

8. Which is the process that releases energy by breaking down food molecules in the presence of oxygen?

A. cellular respiration C. glycolysis

B. electron transport D. photosynthesis

9. Which is the electron carrier that accepts electrons during glycolysis?

A. ADP C. NAD+

B. ATP D. NADP+

10. When comparing cellular respiration and photosynthesis, these two processes are best described as

A. energy-releasing processes. C. opposite processes.

B. energy-storing processes. D. similar processes.

Cell Respiration Web Activity

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Use the website below as an introduction to the 3 steps of cellular respiration: https://goo.gl/Mq3AC9

To begin select “High” for the oxygen level, because cellular respiration is an aerobic process meaning that it can only occur in the presence of oxygen.The first step of cellular respiration is glycolysis. Click on the Play button to answer the questions about glycolysis. You can pause the animation at any time.

Glycolysis: 1. Where does glycolysis take place in the cell?

2. During glycolysis, indicate the quantity of each molecule that is produced for every molecule of glucose:

3. Describe how NAD+ is converted into NADH?

4. During glycolysis does NAD+ become oxidized or reduced? How can you tell?

Krebs Cycle:5. Where in the cell does the Krebs cycle take place?

6. Explain the function of Coenzyme A in Krebs cycle.

7. During the Krebs Cycle, indicate the quantity of each molecule that is produced?

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Electron Transport:8. Describe the location of the electron transport chain.

9. What 2 molecules supply the electron transport chain with high energy electrons?

10. What happens eat time electrons are passed from protein to protein in the electron transport chain?

11. What happens each time hydrogen ions pass through ATP synthase?

12. Describe how ATP Synthase is able to make ATP?

13. How many molecules of ATP are produced from the energy from a single NADH molecule?

14. How many molecule of ATP are produced from the energy from a single FADH2 molecule?

15. Describe how water molecules are created in the electron transport chain?

16. Once the animation has finished playing, click on the button that says “Cellular Respiration Activity” on the left side of the screen. Drag the terms on the left side of the screen to the correct location on the diagram. Once you have finished, label the diagram below.

17. Go back to the home page and click on LOW Oxygen Level. How is this process different from the HIGH Oxygen Level?

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Photosynthesis and Cellular Respiration Review Name:

Biology Date: Period:

1. Distinguish between autotrophs and heterotrophs and give an example of each.

2. Which type(s) of organisms carry out photosynthesis (autotroph/heterotroph)?

3. Why are most plants green?

4. Name the organelle used in photosynthesis.

5. Name the organelle used in cellular respiration.

6. Write the balanced equation for Photosynthesis:

7. Write the balanced equation for Cellular Respiration:

8. What do the two equations have in common?

9. What are the differences between the two equations?

10. How are the two equations they related?

11. Which type(s) of organisms carry out cellular respiration?

12. Name the energy transfer molecule of the cell.

13. Complete the table.Photosynthesis Cellular Respiration

Function

Location

Reactants

Products

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14. What are the three parts of an ATP molecule?

1. _______________________________________

2. _______________________________________

3. _______________________________________

15. Energy is released from ATP when a phosphate group is .

16. Plants get the energy they need for photosynthesis by absorbing .

17. What drives photosynthesis?

18. What are the reactants for photosynthesis?

19. What are the products for photosynthesis?

20. What are the reactants for respiration?

21. What are the products for respiration?

22. What happens if the intensity of light that a plant receives is increased?

23. What happens if the amount of carbon dioxide that a plant receives is increased?

24. What happens if the amount of water that a plant receives is increased?

25. What happens if the temperature a plant receives is increased?

26. What is the name of the organelle?

27. Name the structures in the figure:

A.

B.

C.

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1 2 3

16

17

Look at the diagram to answer the questions or complete the tasks.

1. Color all the CO2 molecules blue.

2. Are the CO2 molecules entering or leaving the Krebs cycle?

3. Every time NAD+ enters a reaction, what is it transformed into?

4. Color NAD+ and NADH red.

5. Every time FAD enters a reaction, what is it transformed into?

6. Color FAD and FADH2 orange.

7. What is added to ADP to make ATP?

8. Color ADP and ATP yellow.

9. For every glucose molecule (remember that each glucose molecule is split into 2 molecules of pyruvic acid) how many of each of the follow molecules are formed?

________ CO2 ________ ATP ________ NADH ________ FADH2

Read the passage to answer the following questions:10. Where does the Krebs cycle take place?

11. What is pyruvate converted into in the first reaction? What molecule is given off during the conversion?

12. List the molecules that are produced for every molecule of acetyl CoA that enters the Krebs cycle.

13. What is the fate of…

a. CO2

b. ATP

c. NADH and FADH2

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Cell Respiration Multiple Choice Reasoning Name:

Biology 6.0 Date: Period:

Circle the correct answer and then explain why the other answers are NOT correct.

1. The primary purpose of cellular respiration in living organisms is to(A) remove excess carbon dioxide from the cells.(B) create water by combining oxygen and hydrogen ions.(C) produce biologically useful energy in the form of ATP.(D) create larger complex molecules such as carbohydrates, proteins, and lipids

2. The reactions in glycolysis occur(A) on the membranes inside the mitochondria.(B) in the fluid matrix of the mitochondria.(C) on the exterior mitochondrial membrane.(D) in the cytoplasm.

3. The products of glycolysis include two pyruvate molecules and(A) two molecules of oxygen.(B) two net molecules of ATP.(C) one molecule of glucose.(D) one molecule of NADH and one molecule of FADH2.

4. If oxygen is not present in sufficient quantity, pyruvate molecules are converted into(A) ethanol or lactic acid.(B) amino acids or fatty acids.(C) carbon dioxide and water.(D) acetyl-CoA and citric acid.

5. Prior to entering the Krebs Cycle, each pyruvate molecule loses electrons, hydrogen ions, and a carbon, forming an energy-rich molecule of(A) NAD+.(B) FADH2.(C) acetyl-CoA.(D) carbon dioxide.

6. The NADH and FADH2 that are formed in the Krebs Cycle primarily function to(A) remove the waste product CO2 from the system.(B) facilitate the production of water by combining hydrogen ions with oxygen.(C) catalyze the production of ATP from ADP.(D) transfer electrons to the electron transport system.

7. The inner folded membrane of the mitochondria serves primarily to(A) separate the many reactions that occur in the organelle.(B) provide increased surface area for the molecules and reactions of the electron transport system.(C) provide a surface for the reaction that unites acetyl with Coenzyme A.(D) produce enzymes that facilitate the splitting of water for oxygen release.

8. When human muscles are exercised and oxygen is depleted, the muscles can continue to produce energy by(A) taking oxygen from other cells and continuing aerobic respiration.(B) breaking down fatty acids.(C) increasing the speed of the reactions in the Krebs Cycle.(D) using fermentation reactions to facilitate glycolysis.

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9. After the Krebs Cycle only a small portion of the energy of glucose has been converted to ATP. At this point the majority of usable energy is contained in(A) NADH and FADH2

(B) pyruvate(C) carbon dioxide(D) citric acid

10. The terminal electron acceptor in mitochondrial respiration is(A) hydrogen(B) NADH(C) oxygen(D) carbon dioxide

11. Fermentation reactions contribute to the continued production of ATP in the absence of oxygen by(A) splitting carbon dioxide and releasing additional oxygen.(B) recycling NADH molecules to NAD+ molecules.(C) producing enzymes that convert ADP to ATP.(D) breaking down ethanol or lactic acid to carbon dioxide and water.

12. Which of the following could be found in autotrophic eukaryotic cells?I. mitochondriaII. chloroplastsIII. nucleus

(A) I only(B) II only(C) III only(D) II and III only(E) I, II, and III

13. All of the following statements are true with regard to mitochondria and chloroplasts EXCEPT(A) Both consist of a double phospholipid bilayer.(B) Both produce ATP.(C) Both are found in heterotrophs.(D) Both have internal structures that increase surface area.

14. All of the following provide evidence of an increased rate of cellular respiration EXCEPT(A) increase in the concentration of CO2.

(B) decrease in the concentration of O2.(C) increased activity of ATP synthase.(D) an increase in the concentration of lactic acid.

15. Which of the following represents a plausible pathway of electrons through the process of cellular respiration?(A) GlucosePyruvateAcetyl-CoAFADH2oxygen(B) GlucoseNADHelectron transport chainAcetyl-CoAoxygen(C) GlucosePyruvateelectron transport chainNADHAcetyl-CoA(D) Glucosecarbon dioxideFADH2electron transport chainAcetyl-CoA

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Group 1

1. Using the diagram above, explain how photosynthesis and cellular respiration are complementary processes.

2. Looking at the diagram above, explain whether anaerobic respiration is energy absorbing or energy releasing process.

3. Provide correct terms for A, X and Y and explain why you chose each term.

4. If B were prevented from occurring, what would be the first measureable effect on organisms performing the above processes?

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Group 2

1. Process A is known asa. Photosynthesisb. Fermentationc. Dehydration synthesisd. Aerobic respiration

2. Glucose is a product of a. Process A, onlyb. Process B, onlyc. Process B and process Cd. Process A and process C

The diagrams below show energy transfer. Complete the chart below by describing energy transformations involved in each process. Describe how energy transformations involved in photosynthesis are related to energy transformations involved in cellular respiration.

Process Energy Transformation

Photosynthesis

Cellular Respiration

Group 3

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Light Energy Chemical Energy(glucose)

Chemical Energy(ATP)

Mechanical Energy

1. What are the gas bubbles in the diagram?

2. In the setup shown in the diagram, which color light will cause the plant to produce the smallest number of gas bubbles?

a. red c. blue b. colorless d. green

3. Explain how the color of light can affect the amount of bubbles produced._______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

4. If the intensity of light is increased, what happens to the amount of bubbles produced?

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

5. What happens if the light is turned off? Think about both sets of reactions in photosynthesis.

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

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Group 4

1. Which of the following best describes the flow of energy in cells?a. Cell work → ATP→ Glucoseb. Glucose → cell workc. ATP → Glucosed. Glucose → ATP → cell work

2. Photosynthesis and cellular respiration are two major processes of carbon cycling in living organisms. Which statement correctly describes one similarity between photosynthesis and cellular respiration?a. Both occur in animal and plant cells.b. Both include reactions that transform energy.c. Both convert light energy into chemical energy.d. Both synthesize organic molecules as food for the cell.

Use the diagram to answer the following questions as thoroughly as possible. In the diagram, molecules A and B represent the products of photosynthesis and molecules C and D represent the products of cellular respiration.3. Explain how photosynthesis and respiration allows for

carbon atoms to be cycled between plants and animals.

4. Describe how energy is transformed as it flows throughout the diagram.

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Biology Keystone Exam Preparation Name:

Photosynthesis and Cellular Respiration Date: Period:

1. A biological process that occurs in plants is represented below.

Which row in the chart below identifies the lettered substances in the process?

A. Row 1 B. Row 2 C. Row 3 D. Row 4

2. Chlorophyll is a molecule shared by prokaryotes and eukaryotes in the process ofA. Cellular respiration C. Protein synthesisB. Photosynthesis D. Polymerization

3. Which of the following best describes the flow of energy in cells?A. Cell work → ATP→ Glucose C. ATP → GlucoseB. Glucose → cell work D. Glucose → ATP → cell work

4. The synthesis of carbohydrates occurs in the stroma of chloroplasts. This process uses energy supplied byA. ATP B. CO2 C. PGAL D. O2

5. Which phrase, if placed in box X, would correctly complete the flowchart shown below?

A. Increased use of starch in root cellsB. Increased concentration of glucose in leaf cells C. Decreased ATP in root cellsD. Decreased concentration of oxygen in leaf cells

6. Photosynthesis and cellular respiration are two major processes of carbon cycling in living organisms. Which statement correctly describes one similarity between photosynthesis and cellular respiration?

A. Both occur in animal and plant cells.B. Both include reactions that transform energy.C. Both convert light energy into chemical energy.D. Both synthesize organic molecules as end products

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7. A biological process that occurs in both plants and animals is shown below.

Which row in the chart below identifies the lettered substances in this process?

A. Row 1 B. Row 2 C. Row 3 D. Row 4

8. Complete the table comparing the processes of aerobic and anaerobic respiration.

Process Location Reactants Products Anaerobic/Aerobic/Both

Glycolysis

Lactic Acid Fermentation

Alcoholic Fermentation

Kreb’s Cycle

Electron Transport Chain

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Using the following list of words, fill in the blanks with the correct term. Some terms may be used more than once.ADPATPATP synthasecarbon dioxidechemiosmosiscytoplasm

diffuseelectron transport chainelectronsFADH2

glucoseglycolysis

greaterintermembrane spaceKrebs Cyclematrixmatrix of mitochondriaNADH/H+

oxygenphosphateproton (H+)pyruvatewater

Aerobic cellular respiration is composed of three steps. The steps in order are ,

and . During , some

of the potential energy of a primary food source, e.g. the sugar , is released during a series of chemical

reactions that occur in the of the cell. , a six-carbon sugar molecule, is

converted to two molecules of , a three-carbon molecule. In addition, a small amount of the

total energy in glucose is stored in a few molecules of , the energy carrier of the cell, and some high energy

electron carriers . Glycolysis does not require and does not generate

the gas .

, the end product of glycolysis is converted to acetyl CoA, with the release of one

molecules of carbon dioxide, for further processing by the that occurs in the

. In the Krebs cycle, some high energy electron carriers

and , and energy carrier, are generated. Two

molecules are released for each cycle of the Krebs cycle.

Glycolysis and the Krebs cycle generate only a small amount of - only 4 molecules per molecule of

glucose. A large amount of the chemical energy from glucose is stored in the form of the electron carriers NADH/H+

generated during and and FADH2 generated ONLY during

the .

The converts the energy stored in NADH/H+ and FADH2

into potential energy in the form of a . The electron transport chain is a series of proteins

located in the . The proteins act as

and some of them are . The first protein of the electron transport chain

accepts from regenerating NAD+ that returns to the function in either

glycolysis or the Krebs cycle. Electrons are then transferred sequentially down the

. The final electron acceptor is which combines with hydrogen

ions (H+) to form . The energy released as the electrons move through certain electron carriers is

used to pump from the of the mitochondria into the

of mitochondria. This results in the that

serves as a potential energy source. The concentration of protons is in the inter membrane

space than in the matrix of the mitochondria. The protons cannot freely across the inner membrane of

the mitochondria. Protons move across the inner membrane via a large protein called

. The energy released by the movement of through the protein is used to

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add a group to to create . This process is called

.

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