Chapter Objectives  You will learn what ATP is  You will explain how ATP provides energy for the cell  You will describe how chloroplasts trap the sun’s energy to make ATP and complex carbohydrates  You will compare ATP production in mitochondria and chloroplasts

Cell Respiration  Cells need energy to do work and to stay alive  Most of the energy comes from carbohydrates (starches & sugars)  Carbohydrates are turned into glucose by digestion  Glucose is taken apart chemically and energy is released

ATP and Respiration  Energy needed by the cell is stored in a special molecule Adenosine triphosphate

 Molecule has 3 phosphate groups  Removing one of the phosphate groups breaks the chemical bond and releases lots of energy  When one phosphate group is removed it becomes Adenosine diphosphate

ADP  Turns back into ATP by bonding back the phosphate group that was removed  Energy to do this comes from glucose when it is broken down chemically  Glucose is broken down in the cytoplasm  The ATP-----ADP cycle occurs in the mitochondria

Energy Cycle Energy + phosphate ATP ADP

Steps in Cell Respiration 1. First step is called Glycolysis 2. 1 glucose molecule is broken down into 2 molecules of pyruvic acid 3. Enough energy is released to change 2 molecules of ADP into 2 molecules of ATP

Glycolysis Glucose 2 ATP Pyruvic Acid

Second Step is Aerobic Respiration  Requires oxygen  2 Steps involved: a.) Citric Acid Cycle (Kreb’s Cycle) b.) Electron Transport Chain (ETC)

Citric Acid Cycle  Begins and ends with the same molecule (Acetyl-CoA)  Pyruvate (formed during glycolysis) enters mitochondria and transforms to Acetyl-CoA.  CO 2 is formed  2 ATP and Hydrogen (H+) ions are formed

Electron Transport Chain (ETC)  Located on inner membrane of Mitochondria  H atoms pass along long chain to produce 34 ATP  Hydrogen atoms passed to O 2 at final electron acceptor to convert the ADP into ATP and form H 2 O

Aerobic Respiration Pyruvate 36 ATP Carbon Dioxide Water

Respiration in Review  Total of 38 molecules of ATP are produced by the 3 steps:  2 ATP from breakdown of glycolysis  2 ATP from breakdown of acetyl- CoA (Krebs Cycle)  34 ATP from E.T.C.

Chemical Equation for Cell Respiration ADP + P + C 6 H CO 2 + 6H 2 0 +ATP

Anaerobic Respiration  First step like aerobic respiration  Second step 1. Pyruvic acid is broken down into CO 2 and either alcohol or lactic acid. 2. During this step no additional energy is released  Net energy produced is only 2 ATP Molecules produced in step one Breaking down glucose w/out oxygen

FERMENTATION  Anaerobic process that breaks glucose down into alcohol or lactic acid, CO 2 and energy.  Takes place in the absence of oxygen  Cell only gets 2 ATP (very inefficient)  Uses for humans: wine, beer, bread, cheese

Anaerobic Respiration Lactic Acid when produced in muscle cells causes them to fatigue very rapidly.

Review of Respiration  ATP is the energy molecule obtained by the break down of glucose. Specifically 2 ATP are formed  When Pyruvic acid is broken down it forms 36 ATP molecules Carbon Dioxide and Water

Photosynthesis Photosynthesis is the process used by plants to :  Obtain the energy needed by organisms and cells  Capture solar energy and change it to usable chemical energy

Photosynthesis Chemical Equation 6 CO H 2 0 C 6 H 12 O O 2 LIGHT CHLOROPHYLL

Photosynthesis occurs in the plant cell chloroplasts  Inside chloroplasts are many folded membranes called grana  Chlorophyll molecules inside of grana trap solar energy  Surrounding the grana is a solution called stroma

Photosynthesis Occurs in two major reactions  Light Reactions  Dark Reactions

Light Reactions  Occur only in light  Chlorophyll traps sunlight  Energy is used to change ADP into ATP  Energy in ATP is used in second series of reactions, used by the cell or stored  A second carrier molecule is also produced NADPH 2

Light Reactions Continued  Occur in the thylakoid membrane and grana of chloroplasts.  Water splits to form hydrogen and oxygen which is then released H 2 O H 2 + O 2

Dark Reactions (Calvin Cycle)  Known as Calvin Cycle  Occurs in both light and dark  Takes place in the stroma of chloroplast  Energy from ATP and NADPH 2 is used to produce glucose and oxygen from water and carbon dioxide

Dark Reactions Continued  Hydrogen combines with carbon dioxide and other compounds to produce glucose  This reaction occurs after the light reactions

Comparing Photosynthesis & Respiration  Photosynthesis 1. Occurs only when light and chlorophyll are present 2. Stores energy in glucose 3. Uses carbon dioxide and water 4. Produces glucose and oxygen 6CO 2 + 6H 2 0 C 6 H 12 O 6 + 6O 2  Respiration 1. Occurs in all cells with or without light & chlorophyll 2. Takes energy from glucose 3. Uses glucose and oxygen 4. Produces Carbon dioxide & water ADP + P +C 6 H 12 O CO 2 + H ATP

Organisms and their food needs Autotroph  An organism that makes its own food For example: plants Heterotroph  An organism that does not make its own food but depends on autotrophs. For example: humans