3Energy ProductionPart of Chapter 9 deals with the catabolic pathways that break down organic molecules for the production of ATP.Whether you are talking about gasoline or sugar, the general equation is:Organic compound + O2 --> CO2 + H2O + Energy
5Energy TransferThe process takes place as the electrons (and hydrogens) in the reactants are transferred to oxygen.It does so in very discrete (small) steps causing the phosphorylation to ADP creating ATP.
7Redox ReactionsThe redox reactions, as they are called, involves an oxidation step that occurs when something loses an electron and a reduction step where a substance gains an electron. *Remember, LEO-GER or OIL-RIG
8Redox ReactionsOxygen is a very powerful oxidizing agent because of its electronegativity.Thus, in redox reactions where electrons are moved closer to oxygen, a lot of chemical energy is given off and is available to do work.
9Redox Reactions Similarities: Burning gas in a car liberates energy in the hydrocarbons and powers the car.Burning glucose in cells within our cells enables us to do work.Cells are much more efficient than other machinery. 40% vs. 15%
10Redox Reactions Within the Cell C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (ATP)*The O2 from respiration oxidizes glucose.
11Glucose MetabolismThe most efficient way to harness the energy in chemical bonds of a fuel is to do so in small discrete steps.Glucose and other organic fuels used by the body are broken down in a series of steps that are each catalyzed by a specific enzyme.
12Glucose MetabolismAt key points in the process, H atoms are stripped from the intermediates and transferred to the coenzyme, NAD+, creating NADH.In a series of steps, NADH transfers electrons to O2 and this makes up the electron transport chain.
13Electron Transport Chain The electron transport chain consists mostly of proteins found in the inner membrane of the mitochondria.The numerous steps of the ETC harness the energy released from the glucose metabolism.
14Electron Transport Chain During the electron transfers, small amounts of energy are transferred and energy is released and used to produce ATP.Ultimately the electrons reach O2 and water is produced.
15Electron Transport Chain Summary In general, the reactions of the ETC can be summed up as:Food-->NADH-->ETC & ATP generation --> O2
16Cellular RespirationThe stages of cellular respiration can be summed up as follows:1. Glycolysis2. The Citric Acid Cycle (aka. The Krebs Cycle)3. Oxidative Phosphorylation
23The Link Between Glycolysis and the Citric Acid Cycle The pyruvate is then converted into acetyl CoA and enters the citric acid cycle where the breakdown of glucose is completed.In this process, CO2 is given off and a small amount of ATP is made, and NADH and FADH2 are generated.
24NADH and FADH2 are Reducing Power NADH and FADH2 are a source of electrons which are used as reducing power within the mitochondrial matrix.Their hydrogens are used to help make ATP.Recall the different ways of reduction.
25A Link Between Glycolysis and the Citric Acid Cycle The three carbon sugar, pyruvate, is now converted into the two carbon intermediate, Acetyl CoA, and is ready to enter the citric acid cycle.
30Electron Transport Chain The NADH and FADH2 produced by the citric acid cycle are used by the electron transport chain which couples electron transport to ATP production.
31ATP Synthase and Chemiosmosis The inner part of the mitochondrial membrane contains many copies of a protein complex called ATP synthase. This is the enzyme that actually phosphorylates ADP making ATP.Chemiosmosis makes use of a proton gradient which exists between the mitochondrial matrix and the intermembrane space.
34ChemiosmosisThe mitochondrial membrane generates and maintains a H+ gradient by using the energy releasing flow of electrons to pump H+ across the membrane from the matrix to the intermembrane space.
39FermentationGlycolysis occurs in the cytoplasm of a cell with or without oxygen producing 2 ATPs.As long as there is a way to regenerate NAD+ when O2 is not available, the cell can keep functioning via glycolysis. (NAD+ is the oxidizing agent).Fermentation is the way the cell continues glycolysis.
40Alcohol Fermentation Alcohol Fermentation: 1. CO2 is released from pyruvate creating acetaldehyde.2. NADH reduces acetaldehyde to ethanol regenerating NAD+Glycolysis is allowed to continue.
41Lactic Acid Fermentation 1. Pyruvate is reduced by NADH forming lactate as an end product.2. Lactate is the ionized form of lactic acidGlycolysis is allowed to continue.