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Chapter 7 Cellular Respiration Mighty Mitochondria http://www.ageofautism.com/2008/04/dr-blaylock-on.html

Chapter 7 Cellular Respiration Mighty Mitochondria

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Page 1: Chapter 7 Cellular Respiration Mighty Mitochondria

Chapter 7Cellular Respiration

Mighty Mitochondria

http://www.ageofautism.com/2008/04/dr-blaylock-on.html

Page 2: Chapter 7 Cellular Respiration Mighty Mitochondria

Vocabulary Pretest Section 1• Cellular Respiration• Pyruvic Acid• NADH• Anaerobic• Aerobic Respiration• Glycolysis• NAD+

• Fermentation• Lactic Acid

Fermentation• Alcoholic Fermentation• Kilocalorie

A. Does not require oxygenB. Anaerobic breakdown of glucose into pyruvic acidC. Breakdown of carbohydrates in the absence of oxygenD. Occurs in muscle cells during periods of strenuous exerciseE. A unit of energy equal to 1000 caloriesF. Occurs when yeast breakdown sugarG. Results in large amounts of ATP (uses oxygen)H. An electron carrierI. The reduced form of NAD+

J. Three carbon compound produced by glycolysisK. The process by which cells obtain energy from carbohydrates

Page 3: Chapter 7 Cellular Respiration Mighty Mitochondria

Answer Key•Cellular Respiration K•Pyruvic Acid J•NADH I•Anaerobic A•Aerobic Respiration G•Glycolysis B•NAD+ H•Fermentation C•Lactic Acid Fermentation D•Alcoholic Fermentation F•Kilocalorie E

Page 4: Chapter 7 Cellular Respiration Mighty Mitochondria

Cellular Respiration

•Cellular Respiration —the process by which cells get energy from carbohydrates; oxygen combines with glucose to form water and carbon dioxide

C6H12O6 + 6O2 6CO2 + 6H2O + energy (ATP)

Page 5: Chapter 7 Cellular Respiration Mighty Mitochondria

•The equation is a simple summary of a very complex process.

•The overall purpose is to convert food into energy by breaking down organic fuel molecules.

•When oxygen is present during this process it is called aerobic respiration ( which is the most efficient).

•If no oxygen is present it is called anaerobic respiration (which is much less efficient).

•Both types (aerobic and anaerobic) start with a process called glycolysis.

Page 6: Chapter 7 Cellular Respiration Mighty Mitochondria

Glycolysis• Glycolysis —first stage of cellular respiration.

▫Glycolysis means “glucose splitting” ▫Occurs in the cytosol▫No oxygen is needed▫Glucose molecules are broken down into two

3-carbon molecules of pyruvic acid▫Pyruvic acid is then used in the Krebs Cycle (which

is the second stage of aerobic respiration)▫Specific enzymes are needed▫2 molecules of ATP are produced▫2 molecules of NADH (an electron carrier molecule)

are produced

Page 7: Chapter 7 Cellular Respiration Mighty Mitochondria

4 stages of Glycolysis

1. 2 phosphates are added to glucose. They are released from 2 molecules of ATP (changing it to ADP).

Page 8: Chapter 7 Cellular Respiration Mighty Mitochondria

2. The glucose molecule (with its 2 phosphates) is then split into 2 molecules of G3P (glyceraldehyde 3-phosphate)

G3PG3P

2 G3P molecules

Page 9: Chapter 7 Cellular Respiration Mighty Mitochondria

3. Each G3P gets oxidized by adding another phosphate group. Also, electrons and hydrogen atoms are removed from the 3C molecule. They are added to 2 molecules of NAD+ (nicotinamide adenine dinucleotide) to create 2 NADH and 2 H+. These will go to the electron transport chain later on.

Page 10: Chapter 7 Cellular Respiration Mighty Mitochondria

4. The phosphate groups are now removed from each molecule creating 2 molecules of pyruvic acid (3C). The phosphates are added to 4 molecules of ADP producing 4 ATP molecules.

Page 11: Chapter 7 Cellular Respiration Mighty Mitochondria

G3PG3P

http://science.halleyhosting.com/sci/ibbio/cellenergy/resp/respirnotes/glycolysis2.htm

Page 12: Chapter 7 Cellular Respiration Mighty Mitochondria

Summary of Glycolysis•Basically:

▫One glucose (6C) is broken into two molecules of pyruvic acid (3C)

▫If oxygen is available, the pyruvic acid will move into the mitochondria and aerobic respiration will begin.

▫4 ATP molecules are produced. Two are used to break apart the next glucose molecule and keep glycolysis going.

▫This leaves a net yield of 2 ATP molecules for use by the cell.

▫Two NAD+ are converted into 2 NADH and 2H+. These go to Electron Transport.

Page 13: Chapter 7 Cellular Respiration Mighty Mitochondria

Efficiency of Glycolysis• Measured in kilocalories (kcal)• One kilocalorie equals 1,000 calories (cal)• Complete oxidation of glucose releases 686 kcal• Production of ATP absorbs 7 kcal• 2ATP are produced from every glucose molecule broken

down by glycolysis• The efficiency is therefore calculated by the following

formula: Efficiency of Energy required to make ATP glycolysis = Energy released by oxidation of glucose

= 2 x 7 kcal x 100% = 2% 686 kcal

Page 14: Chapter 7 Cellular Respiration Mighty Mitochondria

Section 2 Vocabulary Pretest

•Mitochondrial matrix

•Acetyl CoA•Krebs Cycle•Oxaloacetic Acid•Citric Acid•FAD

A. Biochemical pathway that generates ATP

B. 6 carbon compound used in the Krebs cycle

C. Electron acceptor: Flavin adenine dinucleotide

D. The space inside the inner membrane of a mitochondrion

E. 2 carbon compound made from pyruvic acid

F. 4 carbon compound used in the Krebs cycle

Page 15: Chapter 7 Cellular Respiration Mighty Mitochondria

Answer Key

•Mitochondrial matrix D•Acetyl CoA E•Krebs Cycle A•Oxaloacetic Acid F•Citric Acid B•FAD C

Page 16: Chapter 7 Cellular Respiration Mighty Mitochondria

Aerobic Respiration•In most cells, the pyruvic acid produced

in glycolysis enters the pathway of aerobic respiration.

•This pathway produces nearly 20 times as much ATP as is produced by glycolysis alone and is therefore the most efficient.

•Oxygen must be available for this to happen.

•There are two major stages: The Krebs Cycle and the Electron Transport Chain

Page 17: Chapter 7 Cellular Respiration Mighty Mitochondria

Intermediate Step• Aerobic Respiration takes

place in the mitochondria of the cell.

• Before the Krebs Cycle can begin, each of the two pyruvic acid molecules must be converted.

• The pyruvic acid enters the mitochondrial matrix (space inside the inner membrane of the mitochondria)

• It reacts with a molecule called coenzyme A to form Acetyl Coenzyme A (acetyl CoA)

http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 18: Chapter 7 Cellular Respiration Mighty Mitochondria

• Notice that acetyl CoA only has 2 carbon atoms.

• The lost carbon atom is released in a molecule of CO2

• Also, this reaction reduces a molecule of NAD+ to NADH + H+

• This happens to both molecules of pyruvic acid

• Therefore, the end result is: ▫ 2 molecules of Acetyl CoA for

the Krebs cycle▫ 2 molecules of CO2 to be

released▫ 2 molecules of NADH for

electron transport.http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 19: Chapter 7 Cellular Respiration Mighty Mitochondria

The Krebs Cycle

•The Krebs Cycle (named for Hans Krebs) is a biochemical pathway that breaks down acetyl CoA.

•Two turns of the Krebs Cycle produce:▫2 ATP molecules▫4 CO2 molecules▫6 NADH molecule▫2 FADH2 molecules

Page 20: Chapter 7 Cellular Respiration Mighty Mitochondria

5 Steps of the Krebs Cycle1. Acetyl CoA (2 carbon compound)

combines with Oxaloacetic acid (4 carbon compound) to produce Citric Acid (6 carbon compound). This regenerates and releases CoA.

Page 21: Chapter 7 Cellular Respiration Mighty Mitochondria

2. Citric acid releases a CO2 molecule and is oxidized by losing a hydrogen atom. This forms a new 5 carbon compound. The hydrogen atom is transferred to NAD+, reducing it to NADH.

Page 22: Chapter 7 Cellular Respiration Mighty Mitochondria

3. The 5 carbon compound now releases a CO2 molecule and a hydrogen atom. This creates a 4 carbon compound and the hydrogen atom is again added to NAD+, reducing it to NADH. A molecule of ATP is also synthesized from ADP.

Page 23: Chapter 7 Cellular Respiration Mighty Mitochondria

4. The 4 carbon compound releases a hydrogen atom which is used to reduce FAD (Flavin Adenine Dinucleotide) to FADH2. (FAD, like NAD+ also accepts electrons during redox reactions.

Page 24: Chapter 7 Cellular Respiration Mighty Mitochondria

5. The 4 carbon compound now releases a hydrogen atom to regenerate oxaloacetic acid, which can be used to start the Krebs cycle over again. The hydrogen atom released again reduces NAD+ to NADH.

Page 25: Chapter 7 Cellular Respiration Mighty Mitochondria

http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 26: Chapter 7 Cellular Respiration Mighty Mitochondria

Review of the Gylcolysis and the Krebs Cycle

• In Glycolysis, one glucose molecule produces two pyruvic acid molecules, which can then form two molecules of Acetyl CoA.

• Both of the Acetyl CoA molecules enter the Krebs Cycle creating two turns of the cycle.

• This produces 6 NADH, 2 FADH2, 2 ATP and 4 CO2 molecules (waste product that diffuses out of the cell).

• The 6 NADH and 2 FADH2 molecules drive the next stage of aerobic respiration—the Electron Transport Chain.

Page 27: Chapter 7 Cellular Respiration Mighty Mitochondria

Electron Transport Chain

•The Electron Transport Chain, linked with chemiosmosis makes up the second stage of aerobic respiration.▫Electrons are transferred from one

molecule to another by several electron carrying molecules located in the membrane of the mitochondria.

▫All steps occur in the cristae (inner membrane)

▫Follow the steps in the diagram:

Page 28: Chapter 7 Cellular Respiration Mighty Mitochondria

1. ATP is produced when NADH and FADH2 release hydrogen atoms (this regenrates NAD+ and FAD, which return to the Krebs Cycle to be reused) Each hydrogen atom gives up electrons and hydrogen ions (H+)

2. The electrons released are at a high energy level and move down the chain. They lose energy as they move from molecule to molecule.

3. The lost energy is used to pump the hydrogen ions from the matrix to the other side of the membrane.

4. A concentration gradient of hydrogen ions across the membrane is created. 5. H+ are pumped back in by ATP synthase embedded in the membrane.6. ATP is made from ADP and phosphates. 7. Oxygen is the final electron acceptor and also accepts H+ ions to make water.

http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 29: Chapter 7 Cellular Respiration Mighty Mitochondria

Efficiency of Cellular Respiration•Through Aerobic Cellular Respiration, a

maximum of 38 ATP molecules can be produced from one glucose molecule.▫2 from Glycolysis▫2 from Krebs cycle▫32-34 from the Electron Transport Chain

Page 30: Chapter 7 Cellular Respiration Mighty Mitochondria

• To see how we get 38, follow along….▫2 ATPs directly from

glycolysis▫2ATPs directly from

Krebs cycle▫Each NADH can

generate 3ATPs from electron transport (30 total)

▫Each FADH2 can generate 2ATPs from electron transport (4 total)

http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 31: Chapter 7 Cellular Respiration Mighty Mitochondria

• The actual number of ATP molecules generated through Aerobic Respiration varies from cell to cell. (36-38)

• Most eukaryotic cells produce only 36 molecules per glucose molecule because the active transport of NADH through a cell membrane uses up some ATP.

• When 38 ATP molecules are generated the efficiency is calculated as follows:

Efficiency of Energy required to make ATP . Cellular Respiration = Energy released by oxidation of glucose

= 38 x 7 kcal x 100% = 39% 686 kcal

This is 20 times more efficient than glycolysis alone !!

Page 32: Chapter 7 Cellular Respiration Mighty Mitochondria

Anaerobic Respiration• If no oxygen is present, the Krebs Cycle and

Electron Transport Chain are not utilized.• The cell must have a way to keep glycolysis

going. • Glycolysis would stop without a cellular

process that recycles NAD+ and NADH. • Without such a process, glycolysis would

quickly use up all the NAD+ in the cell.• Glycolysis and ATP production would stop and

the cell would die.• Fermentation to the rescue

Page 33: Chapter 7 Cellular Respiration Mighty Mitochondria

Fermentation

•Fermentation is the chemical pathway that recycles NAD+ in the absence of oxygen. It keeps glycolysis going. No additional ATP is made. Therefore, you still have the 2% efficiency rate for energy release.

•Two types of fermentation:▫Lactic Acid Fermentation▫Alcoholic Fermentation

Page 34: Chapter 7 Cellular Respiration Mighty Mitochondria

Lactic Acid Fermentation• Pyruvic acid is converted by a specific enzyme into

lactic acid.• Two hydrogen atoms from NADH and H+ are transferred

to pyruvic acid to form the lactic acid molecule. • NADH is oxidized to NAD+ and reused to keep glycolysis

going.

http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 35: Chapter 7 Cellular Respiration Mighty Mitochondria

•Lactic acid fermentation occurs in foods such as yogurt and cheese as well as certain animal cells.

•Occurs mostly in muscle cells during hard exercise.▫Muscle cells use up

oxygen too fast and switch from aerobic to anaerobic respiration.

▫Lactic acid builds up reducing the cells ability to contract. This causes fatigue, pain and cramps.

http://www.burnthefatchallenge.com/wp/wp-content/uploads/2011/01/treadmill-300x300.gif

Slow down!!! Allow the lacticacid time to diffuse back into the blood stream and to the liverwhere it is converted back intopyruvic acid.

Page 36: Chapter 7 Cellular Respiration Mighty Mitochondria

Alcoholic Fermentation• Converts pyruvic acid to carbon dioxide and

ethyl alcohol.• NAD+ is recycled in the same manner as before.

http://www.methuen.k12.ma.us/mnmelan/Respiration%20L2.htm

Page 37: Chapter 7 Cellular Respiration Mighty Mitochondria

•Bakers use the alcoholic fermentation of yeast to make bread.

•CO2 is produced and trapped in the dough, causing it to rise.

•When the dough is baked, yeast cells die and the alcohol evaporates.

You can’t get drunk from eatingbread !!!

Page 38: Chapter 7 Cellular Respiration Mighty Mitochondria

  PHOTOSYNTHESIS RESPIRATION

FUNCTION   Production of Glucose   Oxidation of Glucose

LOCATION   chloroplasts   mitochondria

REACTANTS   6CO2 + 6H2O   C6H12O6 + 6O2

PRODUCTS   C6H12O6 + 6O2   6CO2 + 6H2O

EQUATION

   light 6CO2 + 6H2O C6H12O6 + 6O2

 C6H12O6 + 6O2 6CO2 + 6H2O +ATP

COMPARING PHOTOSYNTHESIS AND CELLULAR RESPIRATION

Click to reveal