Copyright © 2009 Pearson Education, Inc. PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Chapter 6 How Cells Harvest Chemical Energy Lecture by Richard L. Myers

6.1 Photosynthesis and cellular respiration provide energy for life  Energy is necessary for life processes –These include growth, transport, manufacture, movement, reproduction, and others 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

6.2 Breathing supplies oxygen to our cells for use in cellular respiration and removes carbon dioxide 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

6.3 Cellular respiration banks energy in ATP molecules  Cellular respiration is an exergonic process that transfers energy from the bonds in glucose to ATP –Cellular respiration produces 38 ATP molecules from each glucose molecule –Other foods (organic molecules) can be used as a source of energy as well Copyright © 2009 Pearson Education, Inc.

C 6 H 12 O 6 + 6O2O2 Glucose Oxygen 6 CO 2 Carbon dioxide + 6 H2OH2O Water + ATPs Energy

6.4 The human body uses energy from ATP for all its activities  The average adult human needs about 2,200 kcal of energy per day –A kilocalorie (kcal) is the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1 o C –This energy is used for body maintenance and for voluntary activities –One g of C 6 H 12 O 6 releases 3811 C Copyright © 2009 Pearson Education, Inc.

All that glucose  1 mole of glucose is 180 grams  1 mole of glucose produces 686 Kcal of heat  3.2 moles yields 2200 kcal or 1.25 lbs. glucose  Your brain burns ¼ lb. of glucose per day and uses 15% of the oxygen  75% of energy from food is used to maintain life activities and brain function

6.5  A cellular respiration equation –Glucose loses its hydrogen atoms and is ultimately converted to CO 2 –At the same time, O 2 gains hydrogen atoms and is converted to H 2 O –Loss of electrons is called oxidation (LEO) –Gain of electrons is called reduction (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)

6.5  Enzymes oxidize glucose and other foods – dehydrogenase – removes the hydrogen – requires a coenzyme called NAD + (nicotinamide adenine dinucleotide) to shuttle electrons Copyright © 2009 Pearson Education, Inc.

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

6.6 Overview: Cellular respiration occurs in three main stages  Stage 1: Glycolysis –glucose, (6C) broken into two molecules of a 3 C molecule called pyruvate –This stage occurs in the cytoplasm Copyright © 2009 Pearson Education, Inc.

Stage 2: Krebbs Cycle: also called citric acid cycle –pyruvate is broken down into carbon dioxide and supplies the third stage with electrons –occurs in the mitochondria Copyright © 2009 Pearson Education, Inc.

6.6 Stage 3: Oxidative phosphorylation or the Electron Transport Chain  Oxidative phosphorylation –During this stage, electrons are shuttled through the electron transport chain –Most of the ATP is generated here. –Water is formed –occurs in the inner mitochondrion membrane Copyright © 2009 Pearson Education, Inc.

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

6.7  In glycolysis  Glucose to pyruvate  NAD + reduced to NADH  2 ATP produced Copyright © 2009 Pearson Education, Inc.

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