ADP, ATP and Cellular Respiration

Summary of cellular respiration Copyright Cmassengale www.youtube.com/watch?v=Fcu_8URp4Ac

What Is ATP? Adenosine Triphosphate Energy used by all Cells for: - anabolic reaction - cell growth - tissue repair - movement - reproduction - active transport - active secretion Adenosine Triphosphate Organic molecule containing high-energy Phosphate bonds

Chemical Structure of ATP Adenine Base 3 Phosphates Ribose Sugar

How Do We Get Energy From ATP? By breaking the high- energy bonds between the last two phosphates in ATP making ADP.

How is ATP Re-Made? Another Enzyme is used! ATP ADP +Pi + energy The reverse of the previous process occurs. Another Enzyme is used! ATP Synthetase ATP ADP +Pi + energy

The ADP-ATP Cycle ATP Synthetase ATP-ase (enzyme that breaks ADP to ATP) ATP-ase (Enzyme that breaks ATP to ADP) The creation and usage of ATP and ADP goes in a continuous cycle. ATP-ase is breaking the bonds between the second and third phosphate groups in ATP, releasing energy. That phosphate then makes its way to be connected to another ADP with the help of ATP Synthetase, using up energy to build the bonds back up.

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Glucose The source of energy for cellular metabolism in all organisms (except archaea) How is Glucose ‘Energy’ Chemical Energy (energy stored in the molecular bonds) Bonds break releasing free energy and stable products (exergonic reaction) Copyright Cmassengale

When is ATP Made in the Body? During a Process called Cellular Respiration that takes place in both Plants & Animals

Aerobic cellular respiration C6H12O6 + 6O2 → 6H2O + 6CO2 + 36ATP This just shows the inputs and outputs. There are about 20 reactions in between This is referred to as ‘aerobic’ because oxygen is the electron acceptor when electrons are transferred from the glucose molecule Anaerobic respiration is where electrons from the glucose are transferred to an acceptor molecule other than oxygen Copyright Cmassengale

Cellular Respiration Includes pathways that require oxygen Glucose is oxidized and O2 is reduced Glucose breakdown is therefore an oxidation-reduction reaction Breakdown of one glucose results in 36 to 38 ATP molecules

What Type of Process is Cellular Respiration? An Oxidation-Reduction Process or REDOX Reaction Oxidation of GLUCOSE --> CO2 + H2O (e- removed from C6H12O6) Reduction  O2  to  H2O (e- passed to O2) Cellular respiration is what we call an oxidation-reduction reaction because we use a spare electron removed from a glucose molecule and

What Carries the Electrons? NAD+ (nicotinadenine dinucleotide) acts as the energy carrier NAD+ is a coenzyme It’s Reduced to NADH when it picks up two electrons and one hydrogen ion

Are There Any Other Electron Carriers? YES! Another Coenzyme! FAD+ (Flavin adenine dinucleotide) Reduced to FADH2

Other Cellular Respiration Facts Metabolic Pathway that breaks down carbohydrates Process is Exergonic as High-energy Glucose is broken into CO2 and H2O Process is also Catabolic because larger Glucose breaks into smaller molecules

What are the Stages of Cellular Respiration? Glycolysis The Krebs Cycle The Electron Transport Chain

Where Does Cellular Respiration Take Place? It actually takes place in two parts of the cell: Glycolysis occurs in the Cytoplasm Krebs Cycle & ETC Take place in the Mitochondria

Review of Mitochondria Structure Smooth outer Membrane Folded inner membrane Folds called Cristae Space inside cristae called the Matrix

Diagram of the Process Occurs across Cristae Occurs in Cytoplasm Occurs in Matrix

Beginning of Cellular Respiration: Glycolysis Glycolysis is for both aerobic and anaerobic. Location: Cytosol Overall equation for glycolysis: Glucose  2pyruvate + 2ATP NOTE there are 10 steps involved in the whole process of glycoslysis (see left) you don’t need to know these Also produces 2 NADH and 4 ATP Pyruvate is oxidized to Acetyl CoA and CO2 is removed Copyright Cmassengale

Glycolysis Diagram

Summary of Glycolysis (you need to know) Pyruvic acid = pyruvate For some organisms 2 ATP molecules may be sufficient for energy needs, for others they need to undergo a further biochemical pathway… ADP Copyright Cmassengale

Aerobic cellular respiration Next step in biochemical pathway: Krebs Cycle Location: Mitochondria The 2 pyruvate molecules created in glycolysis enter the mitochondria from the cytoplasm Copyright Cmassengale

A Little Krebs Cycle History Discovered by Hans Krebs in 1937 He received the Nobel Prize in physiology or medicine in 1953 for his discovery Forced to leave Germany prior to WWII because he was Jewish

Krebs Cycle Summary Requires Oxygen (Aerobic) Cyclical series of oxidation reactions that give off CO2 and produce one ATP per cycle Turns twice per glucose molecule Produces two ATP Takes place in matrix of mitochondria

Krebs Cycle The 2 Pyruvate molecules are transferred into the mitochondria They undergo a reaction and become a compound: ‘Acetyl CoA’ and CO2 Acetyl CoA enters the Krebs cycle. Products: CO2 , ATP, loaded acceptor molecules (NADH, FADH2) Loaded acceptor molecules enter and electron transport system on the inner membrane until they are accepted by oxygen If there is no oxygen the krebs cycle stops. The energy released from the electron transport cycle is used to pump H+ from the loaded acceptor molecules into the mitochondrial intermembrane space. This ion gradient drives the production of ATP Copyright Cmassengale

Krebs Cycle Summary Each turn of the Krebs Cycle also produces 3NADH, 1FADH2, and 2CO2 Therefore, For each Glucose molecule, the Krebs Cycle produces 6NADH, 2FADH2, 4CO2, and 2ATP

Krebs Cycle ATP NETS: 3NADH, 1ATP, 1FADH2, & 2CO2

Electron Transport Chain Summary 34 ATP Produced H2O Produced Occurs Across Inner Mitochondrial membrane Uses coenzymes NAD+ and FAD+ to accept e- from glucose NADH = 3 ATP’s FADH2 = 2 ATP’s

Anaerobic cellular respiration No oxygen involved! Begins with Glycolysis, and continues in the cytoplasm as either Alcohol fermentation Lactic acid fermentation Copyright Cmassengale

Glucose  ethanol + carbon dioxide + energy Alcohol Fermentation C6H12O6 → 2CH3CH2O6H + 2CO2 + 2ATP Glucose  ethanol + carbon dioxide + energy Products from glycolysis used are pyruvate, NADH From the pyruvate molecules, a Carbon dioxide molecule is removed to produce acetaldehyde. One the NADH molecules donates a H+ to acetaldehyde to from ethanol. This happens in bacteria and protists, and some plants but alcohol is toxic to plants so they must revert back to aerobic respiration quickly. Copyright Cmassengale

Lactic Acid Fermentation C6H12O6 → 2CH3CH(OH)COOH + 2ATP Glucose  lactic acid + energy Anaerobic respiration in animals Copyright Cmassengale

Fermentation Occurs when O2 NOT present (anaerobic) Called Lactic Acid fermentation in muscle cells (makes muscles tired) Called Alcoholic fermentation in yeast (produces ethanol) Nets only 2 ATP

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Electron Transport Chain Animation