INTRODUCTION TO CELLULAR RESPIRATION Copyright © 2009 Pearson Education, Inc.

Photosynthesis and cellular respiration - energy for life  Together, these two processes are responsible for the majority of life on Earth Copyright © 2009 Pearson Education, Inc. Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts Glucose Cellular respiration in mitochondria H2OH2O CO 2 O2O2  (for cellular work) ATP Heat energy

Photosynthesis and Cellular Respiration  Why do we need Energy?  - Life processes: –Growth, transport, manufacturing, movement, reproduction, etc. Copyright © 2009 Pearson Education, Inc.

Breathing Cellular Respiration Muscle cells carrying out CO 2 + H 2 O + ATP Lungs Bloodstream CO 2 O2O2 O2O2 Glucose + O 2

Cellular respiration: energy in ATP molecules  Cell respiration is exergonic (releases energy)  transfers energy from the bonds in glucose to ATP  Cellular respiration produces 38 ATP molecules from 1 glucose molecule Copyright © 2009 Pearson Education, Inc.

Energy from Electrons  Carbon-hydrogen bonds of glucose are broken  Electrons transfer to oxygen –Oxygen attracts electrons- why? Copyright © 2009 Pearson Education, Inc.

Energy from Electrons  Equation shows changes in hydrogen atom distribution –Glucose loses hydrogen atoms –converted to CO 2 –O 2 gains hydrogen atoms –converted to H 2 O –Loss of electrons- oxidation –Gain of electrons- reduction LEO goes GER Copyright © 2009 Pearson Education, Inc.

C 6 H 12 O O 2 Glucose Loss of hydrogen atoms (oxidation) 6 CO H 2 O + Energy Gain of hydrogen atoms (reduction) (ATP)

STAGES OF CELLULAR RESPIRATION Copyright © 2009 Pearson Education, Inc.

Overview: Cellular respiration occurs in three main stages  #1: Glycolysis- in cytoplasm –Breaking glucose, a six- carbon molecule, into 2 three-carbon molecules called pyruvate Copyright © 2009 Pearson Education, Inc.

Glucose NAD ADP NADH2 P2 2 ATP 2 + H+H+ 2 Pyruvate

Overview: Cellular respiration occurs in three main stages  Link Reaction- in mitochondrial matrix (outer layer) –Breaks off carbon dioxide from pyruvate leaving a 2-carbon molecule –Coenzyme A attaches to this molecule, creating Acetyl-CoA Copyright © 2009 Pearson Education, Inc.

Coenzyme A Pyruvate Acetyl coenzyme A CoA NAD + NADH  H + CO

Overview: Cellular respiration occurs in three main stages  #3: Citric Acid (Krebs) Cycle- in mitochondria –Breaks down pyruvate into carbon dioxide and supplies the third stage with electrons Copyright © 2009 Pearson Education, Inc.

C ITRIC A CID C YCLE NAD + NADH 3 H + CO 2  CoA Acetyl CoA P ADP + ATP FADH 2 FAD

C ITRIC A CID C YCLE CoA 2 carbons enter cycle Acetyl CoA CoA 1 Oxaloacetate 1 Step Acetyl CoA stokes the furnace.

C ITRIC A CID C YCLE CoA 2 carbons enter cycle Acetyl CoA CoA 1 Oxaloacetate 1 Step Acetyl CoA stokes the furnace. 2 3 NAD + NADH CO 2 Citrate ADP + + H + P Alpha-ketoglutarate leaves cycle ATP NAD + NADH CO 2 + H + leaves cycle Steps – NADH, ATP, and CO 2 are generated during redox reactions. 23

C ITRIC A CID C YCLE CoA 2 carbons enter cycle Acetyl CoA CoA 1 Oxaloacetate 1 Step Acetyl CoA stokes the furnace. 2 3 NADH CO 2 Citrate ADP  P Alpha-ketoglutarate leaves cycle ATP NADH CO 2 leaves cycle Steps – NADH, ATP, and CO 2 are generated during redox reactions NAD + NADH Malate + H + 4 FADH 2 FAD Succinate Steps – Redox reactions generate FADH 2 and NADH. 45 NAD + + H + NAD + + H +

Overview: Cellular respiration occurs in three main stages  #3: Oxidative phosphorylation- inner mitochondria membrane –electrons are shuttled through the electron transport chain –ATP is generated through chemiosmosis (movement of H+ across a membrane) Copyright © 2009 Pearson Education, Inc.

ATP H+H+ Intermembrane space O2O2 H2OH2O 1212 Inner mitochondrial membrane H+H+ NAD + H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ Mitochondrial matrix Electron flow Electron carrier Protein complex of electron carriers NADH FADH 2 FAD ATP synthase P ADP + Chemiosmosis + 2 O XIDATIVE P HOSPHORYLATION Electron Transport Chain

Mitochondrion CO 2 NADH ATP High-energy electrons carried by NADH NADH C ITRIC A CID C YCLE G LYCOLYSIS Pyruvate Glucose and FADH 2 Substrate-level phosphorylation Substrate-level phosphorylation O XIDATIVE P HOSPHORYLATION (Electron Transport and Chemiosmosis) Oxidative phosphorylation ATP Cytoplasm Inner mitochondrial membrane

CONNECTION: Certain poisons interrupt critical events in cellular respiration  Cellular poisons that affect cellular respiration: –1: blocks electron transport chain –rotenone, cyanide, and carbon monoxide –2: inhibits (stops) ATP synthase –oligomycin –3: makes the membrane leaky to hydrogen ions –dinitrophenol- used to make dyes, explosives and pesticides Copyright © 2009 Pearson Education, Inc.

ATP H+H+ O2O2 H2OH2O 1212 H+H+ NAD + NADH FADH 2 FAD PADP + Chemiosmosis + 2 Electron Transport Chain H+H+ H+H+ H+H+ H+H+ Rotenone Cyanide, carbon monoxide H+H+ H+H+ Oligomycin ATP synthase DNP H+H+ H+H+ H+H+

Fuel for Cell Respiration  Glucose- primary source of sugar  Three types of molecules needed to make ATP: –Carbohydrates (disaccharides) –Proteins (in form of amino acids) –Fats Copyright © 2009 Pearson Education, Inc.

Food, such as peanuts ProteinsFatsCarbohydrates Glucose O XIDATIVE P HOSPHORYLATION (Electron Transport and Chemiosmosis) CITRIC ACID CYCLE Acetyl CoA GLYCOLYSIS Pyruvate Amino acids Glycerol Sugars Fatty acids Amino groups G3P ATP

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