CHAPTER 5BCELLULAR RESPIRATION

Where does the energy of life come from?

Radiant energy Chemical

energy

Photosynthesis Respiration

CELL ACTIVITIES

RESPIRATION

The release of chemical energy for cellular use

*Takes place in small steps…

Occurs in the MITOCHONDRIA

Done by HETEROTROPHS and some AUTOTROPHS

Respiration

CELLULAR RESPIRATIONMolecules are broken down inside the

cell to release energyC6H12O6 + oxygen CO2 + H2O + energy2 Types 1. Aerobic:oxygen is present2. Anaerobic:no oxygen present

glucose2 Pyruvic Acids

Alcoholic

Fermentation

Lactic Acid

Fermentation

Ethyl Alcohol and Carbon Dioxide

Lactic Acid

Anaerobic

Respiration

Aerobic Respiration

Acetyl Co-A

Krebs Cycle

E- transport chain

CO2

H2OATP

CYTOPLASM

MITOCHONDRIA

Cellular Respiration

1. Glycolysis -Doesn’t require oxygen

-Takes place in the cytoplasm -Main function is to take 1

C6H12O6 and make PYRUVIC ACID

A. Glucose is phosphorylated by 2ATP molecules forming a new 6C molecule (very unstable)

B. Molecule splits into 2, 3C, PGALC. Each PGAL gains a “P” group,

floating in the cells environment.

D. At the same time NAD+ removes two H+ atom to form NADH + H+

E. The PGAL loses 2 “P” groups each to ADP

4ADP4 ATP PGAL is converted to PYRUVIC ACIDH2O is lost

Glucose

PGAL PGAL

PGAL + P

PGAL + P

Pyruvic Acid

Pyruvic Acid

ATP ATP

ADP ADP

NAD

NADH

2 ADP

2ATP

P P

NAD

NADH

2 ADP

2ATPH2O

OVERALL ENERGY RESULTS

OF GLYCOLYSIS1. Used 2 ATP’s

Made 4 ATP’s NET GAIN: 2 ATP’s2. Gained 2 NADH+ H+3. 2 (3C) Pyruvic Acid’s

1. Anaerobic Respiration Fermentation - The breaking down of Pyruvic Acid

without oxygen - Occurs in the CYTOPLASM - NO ATP produced - Pyruvic Acid Regenerates NAD+ to

be used in glycolysis lactic acid fermentation alcoholic fermentation

A. Lactic Acid Fermentation:

Alternative pathway that converts Pyruvic acid lactic acidDuring exercise breathing rates increase to supply more O2

Enough for Aerobic Exercise (EX: Walking, swimming, jogging)Anaerobic exercise will result in O2 debt (Ex: Weight lifting, sprinting)

Feel the Burn…If there is not enough O2 available lactic acid will begin to accumulate in the musclesBurning sensation is the result of lowering the muscle pHBlood takes the lactic acid to the liver and breaks it down to pyruvate

B. Alcoholic Fermentation: Without O2 NADH gives H+ to pyruvic acid pyruvic acid ethyl alcohol + CO2 + NAD+ Wine Formation: Sugar in grapes is broken down with

glycolysis Dry Wine: Fermentation until all

sugar is used up Sweet Wine: Alcohol inhibits

fermentation before all sugar is used up

Pyruvic Acid Fermentation

Lactic Acid

NADH+HNADTo Glycolysis

Carbon Dioxide

FermentationEthyl

Alcohol

To Glycolysis NADNADH+H

Pyruvic Acid

2. Aerobic RespirationGlycolysis followed by the breakdown of pyruvic acid using oxygenOccurs inside the MITOCHONDRIAPyruvic acid formed in the cytoplasm diffuses across the membrane into the MATRIX

1. Conversion of Pyruvic Acid 2. Krebs Cycle 3. Electron transport chain

The Mitochondrion

A. Conversion of Pyruvic Acid

1. Pyruvic acid loses a C to form CO2 and a H that is picked up by NAD + Forming an Acetyl group & NADH + H+.

2. Acetyl group then picks up COENZYME A to form Acetyl-CoA.

NAD

NADH +H

CO2

CO A

CoA

ACETYL CoA

Pyruvic Acid

The Krebs

Cycle

Pyruvic AcidCO2

CO2

CO2

CoA

Citric Acid (6C)NAD

NADH + H

Ketoglutaric Acid (5C) NAD

NADH + H

NADH + H

NAD

ADPATP

Succinic Acid (4C)

FAD

FADHMalic Acid (4C)

Oxaloacetic Acid (4C)

Acetyl – CoA (2C)

NAD

NADH + H

CoA

B. Kreb’s Cycle or Citric Acid Cycle

Discovered by Hans KrebsReleases CO2 and hydrogen ions and results in the formation of ATP

Steps of the Kreb’s

1. Acetyl CoA gives up the CoA and binds with (4C) Oxaloacetic Acid to form CITRIC ACID (6C)

2. Citric Acid (6C):releases H ion to NAD+ to form NADH + H+ C to form CO2 - this results in KETOGLUTARIC ACID (5C)

3. Ketoglutaric Acid (5C):H ion to NAD+ to form NADH + H+C to form CO2

phosphate group to ADP to form ATP –this results in SUCCINIC ACID (4C).

4. Succinic Acid: gives up H to FAD to create FADH2 – results in MALIC ACID (4C)

5. Malic Acid:H+ ion to NAD+ to form NADH + H+ - this results in OXALOACETIC ACID (4C) - the starting and stopping part of the Kreb’s Cycle

Krebs

Cycle

Pyruvic AcidCO2

CO2

CO2

CoA

Citric AcidNAD

NADH + H

Ketoglutaric AcidNAD

NADH + H

NADH + H

NAD

ADPATP

Succinic AcidFAD

FADHMalic Acid

Oxaloacetic Acid

Acetyl - CoA

NAD

NADH + H

CoA

Overall Results Of Krebs CycleFrom one C6H12O6 molecule the following is

formed…..-6 NADH + H+ (3 each pyruvic acids)-4 CO2 (2 each pyruvic acid)-2 ATP (1 per pyruvic acid)-2 FADH (1 per pyruvic acid)

Overall Results: Glycolysis + Kreb’s Cycle-4 ATP (2 from glycolysis, 2 from Kreb’s)-10 NADH +H+ 30ATP-2 FADH2 4 ATP

C. Electron Transport Chain-Occurs across the inner membrane of the

mitochondria-Consists of enzymes, carrier molecules

Steps of Electron Transport1. NADH + H+ and FADH2 from the

Krebs cycle arrives at the electron transport chaine- are released and move down the chain, releasing energy.Oxygen is the final e- acceptor

2. At the same time… NADH+ H+ and FADH2 deliver H+, Across the inner membrane out of the matrix.This Creates a concentration gradient

3. Ions want to diffuse across the membrane down their concentration gradient.

4. Hydrogen move across the membrane through ATPsynthetase… ATP is made. CHEMIOSMOSIS

5. The diffused hydrogen ions are picked up by incoming oxygen to form water.

*This is a continuous process, oxygen removes H+ while NADH+H+ and FADH2 replace it.

NADH + H+

FADH2 H+

H+

MATRIX

MATRIX

O2

H2O

e-

MATRIX

H+

ADP + PATP

ATP

Synthetase

ENERGY RESULTSScientists have determined….

-After Krebs and Glycolysis- 10 NADH give 3 ATP’s each and total 30

ATP’s 2 FADH give 2 ATP’s each and total 4 ATP’s 34 ATP’s/

glucose Total ATP/glucose Glycolysis 2 ATP Krebs 2 ATP e- transport 34 ATP 38 ATP/glucose

2 NADH + H+

2 NADH + H+

6 NADH + H+

2 FADH2

2ATP

ADP

2ATP

2ATP

34 ATP

38 ATP’S

KREB’S

2PGAL

Glu

c ose

2 P.

A.

2 Acetyl Co-A

Glycolysis

E-.Transport Chain

Respiration Overview

The Chemistry…The chemical reactions of photosynthesis and respiration are oppositesPhotosynthesisCO2 + H2O + ENERGY (C6H12O6) + O2

RespirationC6H1206 + O2 CO2 + H2O + ENERGY