INTRODUCTION TO CELLULAR RESPIRATION Copyright 2009 Pearson Education

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 Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts CO 2 Glucose H 2 O O 2 Cellular respiration in mitochondria ATP (for cellular work) Heat energy Copyright © 2009 Pearson Education, Inc.

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

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

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

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

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

Glucose 2 ADP 2 NAD+ + 2 P 2 NADH 2 ATP + 2 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-Co. A Copyright © 2009 Pearson Education, Inc.

NADH H+ NAD+ 2 Co. A Pyruvate 1 CO 2 3 Coenzyme A Acetyl coenzyme A

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.

Acetyl Co. A CITRIC ACID CYCLE 2 CO 2 3 NAD+ FADH 2 3 NADH FAD 3 H+ ATP ADP + P

Co. A Acetyl Co. A 2 carbons enter cycle Oxaloacetate 1 CITRIC ACID CYCLE Step 1 Acetyl Co. A stokes the furnace.

Co. A Acetyl Co. A 2 carbons enter cycle Oxaloacetate 1 Citrate NAD+ 2 NADH + H+ CITRIC ACID CYCLE CO 2 leaves cycle ADP + P ATP Alpha-ketoglutarate 3 CO 2 leaves cycle NADH + H+ Step 1 Acetyl Co. A stokes the furnace. NAD+ Steps 2 – 3 NADH, ATP, and CO 2 are generated during redox reactions.

Co. A Acetyl Co. A 2 carbons enter cycle Oxaloacetate 1 Citrate NADH + H+ NAD+ 5 NAD+ 2 NADH + H+ CITRIC ACID CYCLE CO 2 leaves cycle Malate ADP P FADH 2 4 ATP FAD Alpha-ketoglutarate 3 CO 2 leaves cycle Succinate NADH + H+ Step 1 Acetyl Co. A stokes the furnace. NAD+ Steps 2 – 3 NADH, ATP, and CO 2 are generated during redox reactions. Steps 4 – 5 Redox reactions generate FADH 2 and NADH.

Overview: Cellular respiration occurs in three main stages § #3: Oxidative phosphorylationinner 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.

Intermembrane space Protein complex of electron carriers H+ H+ Electron carrier H+ H+ ATP synthase Inner mitochondrial membrane FADH 2 Electron flow NADH Mitochondrial matrix FAD NAD+ H+ 1 2 O 2 + 2 H+ H+ H+ H 2 O Electron Transport Chain OXIDATIVE PHOSPHORYLATION ADP + P H+ Chemiosmosis ATP

NADH Mitochondrion High-energy electrons carried by NADH FADH 2 and OXIDATIVE GLYCOLYSIS Glucose PHOSPHORYLATION (Electron Transport and Chemiosmosis) CITRIC ACID CYCLE Pyruvate Cytoplasm ATP Substrate-level phosphorylation CO 2 ATP CO 2 Substrate-level phosphorylation Inner mitochondrial membrane ATP Oxidative phosphorylation

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.

Cyanide, carbon monoxide Rotenone Oligomycin H+ H+ H+ ATP synthase H+ H+ DNP FADH 2 FAD 1 2 NAD+ NADH O 2 + 2 H+ H+ H+ H 2 O H+ Electron Transport Chain ADP + P ATP Chemiosmosis

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 Carbohydrates Fats Glycerol Sugars Proteins Fatty acids Amino groups Glucose G 3 P Pyruvate GLYCOLYSIS Acetyl Co. A ATP CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis)

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