Cellular Respiration Objectives: Summarize how glucose is broken down in the first stage of cellular respiration. Describe how ATP is made in the second stage of cellular respiration. Identify the role of fermentation in the second stage of cellular respiration. Evaluate the importance of oxygen in aerobic respiration.
Cellular Respiration Is a series of reactions where fats, proteins, and carbohydrates, mostly glucose, are broken down to make CO 2, water, and energy.
Mitochondria Site of cellular respiration Inter membrane – area between outer and inner membranes – contains a high H+ concentration- (acidic) Matrix – area inside the inner membrane – low concentration of H+ (less acidic) Cristae – folds in the inner membrane – allows for greater surface area Inter membrane
ATP Most of the energy from cell respiration is converted into ATP ATP is a substance that powers most cell activities.
Vocabulary Cellular Respiration – the transfer of energy from an organic compound into ATP Fermentation – the breakdown of carbohydrates by enzymes, bacteria, yeasts, or mold in the absence of oxygen Pyruvate- an ion of a three-carbon organic acid called pyruvic acid.
Aerobic respiration A. Breakdown of pyruvic acid – Forms acetyl-CoA
II. Citric Acid Cycle (Krebs Cycle) Chemical process that produces more ATP and releases additional electrons (FADH 2 and NADH) Occurs in the mitochondria Cycle will happen twice per molecule of glucose Net ATP = 2
Electron Transport Chain Groups of redox proteins – On inner mitochondrial membrane – Binding sites for NADH and FADH 2 On matrix side of membrane Electrons transferred to redox proteins NADH reoxidized to NAD + FADH 2 reoxidized to FAD
4 Complexes proteins in specific order Transfers 2 electrons in specific order – Proteins localized in complexes Embedded in membrane Ease of electron transfer – Electrons ultimately reduce oxygen to water 2 H + + 2 e - + ½ O 2 -- H 2 O
Complex 1 Removes two electrons from NADH and transfers them to a lipid-soluble carrier, ubiquinone (Q), which dissolves into the membrane.ubiquinone At the same time, Complex I moves four protons (H + ) across the membrane, producing a proton gradient.
Complex II - Succinate Is not a proton pump. It serves to funnel additional electrons into the quinone pool (Q) by removing electrons from succinate and transferring them (via FAD) to Q.FAD Point of entry for lipids and some out molecules into the chain.
Complex III Removes two electrons from QH 2 at the Q O site Transfers them to two molecules of cytochrome c, a water-soluble electron carrier located within the intermembrane space.cytochrome c The two other electrons passed across the protein quinone, which is reduced to quinol.
Complex IV Removes four electrons from four molecules of cytochrome c cytochrome c Transfers electrons to molecular oxygen (O 2 ), producing two molecules of water (H 2 O). At the same time, it moves four protons across the membrane, producing a proton gradient.
Generation of ATP Proton gradient is used by the F O F 1 ATP synthase complex to make ATP via oxidative phosphorylation. ATP synthase is sometimes regarded as complex V of the electron transport chain.
Generation of ATP Part 2 The F O component of ATP synthase acts as an ion channel for return of protons back to mitochondrial matrix.ATP synthaseion channel Proton Gradient (H+) that was created through the moving of the electron through the ETC is used by the ATP Synthase to create ATP Coupling with oxidative phosphorylation is a key step for ATP production.
Generation of ATP part 3 Step 1: H+ (protons) enter into ATP synthase at the F0 end. Step 2: F0 end acts like a Ferris or Water Wheel. The Proton gets on and spins the F0 section which causes the F1 section to move Step 3: The F1 moves once for each of the H+ ions moving through F0 Step 4: F1 Moves through the following sequence: Open – Bind/lock – Close – Open – ATP released from binding site on the ATP Synthase Enzyme leaving it open. – Bind/Lock – ADP and Pi (Inorganic Phosphate) bind to the binding site and are locked into place – Close – ATP Synthase f1 portion slams shut forcing the ADP + Pi together to make ATP
Anaerobic Respiration Occurs when no oxygen is available Fermentation – Anaerobic process of breaking down pyruvic acid (pyruvate) – Two types of anaerobic respiration Lactic acid fermentation Alcoholic fermentation
Lactic Acid Fermentation Lactic acid is formed Humans ferment lactic acid in muscles Causes muscle stiffness after beginning exercise programs
Alcoholic fermentation Formation of alcohol from sugar Yeast converts glucose to pyruvic acid (pyruvate) Then converts pyruvic acid (pyruvate) into ethanol (ethyl alcohol), a C-2 compound Ethanol produced is found in beer, wine, and other alcoholic beverages