Lecture 3 - Cellular Respiration.docx

**Topic:** Lecture 2 + 3 - Cellular Respiration Cellular Metabolism Intermediary Metabolism - definition - anabolism and catabolism - Energy diagram ATP "Adenosine TriPhosphate" "The main currency" - Definition - Process - Extraction by cell machinery, converted into energy...

**Topic:** Lecture 2 + 3 - Cellular Respiration Cellular Metabolism Intermediary Metabolism - definition - anabolism and catabolism - Energy diagram ATP "Adenosine TriPhosphate" "The main currency" - Definition - Process - Extraction by cell machinery, converted into energy source = high energy phosphate bonds of ATP - ADP - low energy molecule (Adenosine DiPhosphate) - Finite limit to how much energy can store and make - How ATP is produced? - Creatine Phosphate - Anaerobic Glycolysis - Aerobic Metabolism - Most → Substrate level Phosphorylation: Creatine Phosphate - When cell has a lot of ATP, it can take that energy ATP and add to Creatine molecule = ADP - Creatine Kinase = the enzyme reaction - Can change ATP → ADP and ADP → ATP - Ex. You're on a shopping spree and a situation happens where you need an excess amount of cash (energy). You go into you reserves and get your bitcoin (ADP). You can pay the cashier with bitcoin so you have to transfer it at the bank (creatine kinase) to get cash to pay for the item Stages of Respiration - 32 ATP per molecule of Glucose - Diagram - Glycolysis happens in cytosol **Important Definitions** Creatine Kinase Anabolism Catabolism ATP Cytosol Potential Exam Q's - Breakdown glucose (our body\'s fav source) to make ATP (energy) - Glucose = 6 carbons - Total avg ATP we make = 32 Notes **Section 1: Cellular Metabolism : Respiration** Glycolysis - takes place in the Cytosol - 10 chemical reactions (to make One 6-Carbon molecule into Two 3-Carbon Pyruvate molecule) - Glucose (6 carbon) into 2 Pyruvates (3 carbon) - \***Generation or Net Gain of 2 ATP during Glycolysis (also generate 2 NaDH molecules; very high energy electrons) per molecule of Glucose** - Rest of the energy is contained in the chemical bonds. - \***McArdle Disease**: absence of an enzyme involved in the first step of glycolysis (glycogen to glucose conversion). - What is **Glycogen?:** Deposit in the Cytosol where glucose is stored. - Still can breakdown glucose to pyruvate, problem is converting deposits of glycogen. No problem with glycolysis itself.\* - **Q? For TA: So with this disease, it cannot use the glycogen stored in the Cytosol to create energy only the glucose that has not been converted / stored as glycogen? (Lecture 3 8:15)** **Step 2 Pyruvate Decarboxylation** - pyruvate generated goes from Cytosol into mitochondrial matrix - 1 step reaction catalyzed into Acetyl CoA (2 carbon molecule) \[called decarboxylation due to loss of 1 carbon molecule) - Two 3-Carbon Pyruvate converted into Two Acetyl CoA molecules - **Exam Question**\* - How many Acetyl CoA, Pyruvate, or Co2, are generated from 1 Glucose molecule? \[12:10 Lecture\] - One 6-Carbon Glucose Molecule produced Two 3-Carbon Pyruvate Molecules - One 6-Carbon Glucose Molecule produced Two Acetyl CoA molecules - One 6-Carbon Glucose Molecule produced 2 CO2 molecules - 1 NADH is generated per Pyruvate Decarboxylation reaction (So in total 4 NADH have been generated - two from Glycolysis and two from Pyruvate Decarboxylation); still have 2ATP; Co2 eliminated **Step 3 Krebs Cycle.** Acetyl CoA (2C) enters into TCA (Krebs Cycle or Tricarboxylic Acid Cycle) cycle. Acetyl CoA (2C) combines with Oxaloacetate (4C molecule) making Citric Acid (6C) - Series with 8 reactions in Krebs Cycle - Lose 2 CO2 molecules during this process of reactions, to regenerate Acetyl CoA - Both carbon (C) and oxygen (O) from glucose molecule - (Lost Two CO2 molecules in Pyruvate Decarboxylation, now lost two in Krebs Cycle) - 2C converted into CO2 - 3 NADH molecule formed per TCA cycle; there are two Acetyl CoA that goes into the Krebs Cycle = 6 NADH formed - 1 FADH molecule formed per TCA cycle; there are two Acetyl CoA that goes into the Krebs Cycle = 2 FADH formed Step 4 - Hydrogen molecules are also removed during the Citric Acid Cycle. - Products per one turn of cycle (For every Acetyl CoA) - 2 CO2 molecules - 1 ATP - 3 NADH - 1 FADH2 Total before Oxidative Phosphorylation - ATP: 4 - NADH: 10 - FADH: 2 What does NADH stand for: Nicotinamade Adenine Dinucleotide (NAD+) What does FADH stand for: Flavine Adenine Dinucleotide Step 5: Electron Transport Chain: Oxidative Phosphorylation - Most of energy still stored in Hydrogen - 28 ATP produced, extracted from NADH and FADH2 - Where the most energy is produced - Electron carrier molecules found in inner membrane of mitochondria - NADH and FADH converted back to NAD+ and FAD, free to pick up new H molecules - 1 NADH = 2-3 ATP (2.5 ATP) - 1 FADH2 = 1-2 ATP (1.5 ATP) Chemiosmosis: ATP synthase catalyzes ATP synthesis using energy from the H+ gradient across the membrane. Aerobic Conditions (normal conditions, when oxygen is present(breathing) Glycolysis to Pyruvate Decarboxylation to Krebs Cycle to Oxidative Phosphorylation. Anaerobic Conditions: If there's limited oxygen, Pyruvate is not converted into Acetyl CoA but Lactate instead and does not enter TCA.