BIOLOGY 111 1st Edition Lecture 11 Outline of Last Lecture I. EquilibriumA. Open vs Closed systemsB. Exergonic reactions and Endogonic reactionsII. ATPIII. Catalyst A. Enzyme and RibozymesB. Activation Energy and Transition StateIV. EnzymesA. PurposeB. Active Site and Induced FitC. Environment factorsV. Inhibitors A. Competitive vs Noncompetitive inhibitorB. Feedback inhibitor Outline of Current Lecture I. Energy FlowII. Cellular RespirationIII. Redox ReactionsIV. Pathways of Cellular RespirationV. Cancer CellsVI. Catabolism VII. Feedback Inhibition Current LectureEnergy flow- Energy flows into an ecosystem as sunlight and leaves as heatThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- The chemical elements essential to life are recycled - Photosynthesis generates oxygen and organic molecules used by mitochondria as fuel for cellular respiration- Carbon dioxide and water are the products of photosynthesis- The reactants create products and the products are used as the reactants in a continuous cycle.Cellular Respiration- Includes aerobic (with oxygen) and anaerobic (without oxygen) processes, although it mostly refers to aerobic process. - It is a metabolic process (i.e. burning fuel)- Fats, proteins, carbohydrates (glucose) are broken down to make carbon dioxide, water and energy.- Glucose is most often used by cells- Exergonic (free energy of -686kcal per mole)- This means glucose products contain less energy than the reactant (glucose) and it occurs spontaneouslyRedox Reactions- When in a chemical reaction, there is a transfer of one or more electrons from one reactant to another. (Oxidation-Reduction reaction)- Electrons are transferred to more electronegative atoms, forming a more stable arrangement.- Oxidation – loses electrons [considered oxidized because increasing the positive charge by losing an electron (negative charge)]- Oxidizing Agent – electron acceptor (the one being reduced) - Reduction – gains electrons [considered a reduction because decreasing the positive charge by gaining an electron(negative charge)] - Reducing Agent – electron donor (the one being oxidized)- Dehydrogenations - lost electrons are accompanied by hydrogen [therefore what is lost is a hydrogen atom (1 electron and 1 proton)]- Aerobic Process (In the presence of oxygen) - The oxidation of glucose provides abundant energy, making about 36 molecules of ATP for every molecule of glucose. ***Glucose is ALWAYS oxidized***- Oxidation of glucose occurs in several small steps (this allows the cell to capture energy for further use which is stored by NAD+)- NAD+: for every conversion of NAD+ to NADH, 2 hydrogens are removed from substrate (one H is binding, the other H is released)- NADH: passes the electrons to the electron transport chain Three Metabolic pathways of Cellular Respiration- the harvesting of energy from glucose by cellular respiration is a cumulative function of the following pathways:1. Glycolysis (“sugar splitting”)- Occurs in the cytosol- Begins the degradation process by breaking glucose into two molecules of pyruvate- With Oxygen, Pyruvate enters the mitochondria and is oxidized into acetyl CoA and enters the Krebs cycle. (per molecule of pyruvate, products include: 1 CO2, 1 NADH, and 1 acetyl CoA which consist of 2 carbons from pyruvate attached to coenzyme A)- Without Oxygen, Pyruvate is reduced and oxidizes NADH back to NAD+ which is a process called Fermentation- Respiration yields more ATP (16 times as much ATP) than Fermentation- Substrate-level phosphorylation – formation of a small amount of ATP 2. Citric acid cycle (Kreb’s cycle)- This is where the acetyl CoA enters - Steps (per cycle) include: - release of 2 molecules of CO2 (per 1 cycle)- reduce 3 NAD+ to 3 NADH (per 1 cycle)- reduce 1 FAD to FADH2 (per 1 cycle)- produce 1 ATP (per 1 cycle)- the cycle turns twice for each original glucose molecule - Coenzyme A: the remaining 2 carbons (not used for CO2) attach to this carrier molecule (that is a sulfur containing compound derived from vitamin B)- Carbon dioxide produced by respiration represents fragments of oxidized organic molecules - Substrate level phosphorylation- Oxidative phosphorylation (most of the ATP synthesis occurs at this stage) After glycolysis, pyruvate oxidation, and the kreb’s cycle, glucose has been oxidized to: o 6 Carbon Dioxide moleculeso 4 ATP o 10 NADHo 2 FADH2*The 10 NADH and 2 FADH2 are passed on to the electron transport chain- The ETC (electron transport chain) accepts electrons from the breakdown products of the first two stages (through the NADH) and passes these electrons from one molecule to another. At the end of the chain, the electrons are combined with molecular oxygen and hydrogen ions, forming water. The energy released at each step is stored in a form the mitochondria can make use of (i.e. ATP from ADP)- Chemiosmosis – the energy stored in the form of hydrogen ion gradient across a membrane is used to drive cellular work (i.e. ATP synthesis) - For each molecule of glucose degraded into Carbon Dioxide and water by respiration, the cell makes about 32 molecules of ATP.Cancer cells favor glycolysis - Warburg effect – cancer cells preferentially use glycolysis while decreasing oxidative phosphorylation (this isn’t the cause, it is the result)- Glycolytic enzymes are expressed in 80% of all types of cancer- Caused by genetic and environmental factors (i.e. mutations, low oxygen…)Catabolism- Carbohydrates, fats, and proteins can all be used as fuel for cellular respiration. Monomers of these molecules enter glycolysis or citric acid cycle at various points.- Proteins enter as amino acids and before they can enter glycolysis or citric acid cycle, theamino group must be removed which is called deamination.- Fats are digested as glycerol and fatty acids- Glycerol is converted to glyceraldehyde 3-phosphate and enters glycolysis - Fatty acids are broken down by beta oxidation into two-carbon fragments before they can enter Kreb’s cycle as acetyl CoAFeedback Inhibition - Regulates Cellular Respiration by allosteric enzymes that set the pace of glycolysis and citric acid cycle. - If your body has enough ATP, then the process stops and excess food molecules are stored as glycogen or