Glycolysis, Krebs Cycle, and Electron Transport System A review for the confused (like me!) Regina Lamendella AP Biology December 16, 2008

What is happening while you ingest donuts??

Doughnut = glucose = electrons What is the purpose of glycolysis and cellular respiration? Doughnut = glucose = electrons = Electrons

Overview Video Write down the major “take home messages” from the video

Glycolysis 10-STEP reaction (Rxns 1-5) Glucose is phosphorylated and cleaved to yield 2 molecules of triose glyceraldehyde-3-phosphate. This process uses two ATPs. (Rxns 6-10): The molecules of glyceraldehyde-3-phosphate are converted to pyruvate, with concomitant generation of four ATPs and two NADH per glucose. How many net ATPs?

Glycolysis Where are we within the cell? What does ATP stand for? What does NAD stand for? How many carbons does pyruvate have? 1 ATP 2 NAD+

Adenosine Tri-Phosphate

Nicotinamide Adenine Dinucleotide

Nicotinamide Adenine Dinucleotide H

Overall reaction for glycolysis Glucose + 2 NAD+ + 2 ADP + 2 Pi  2 NADH + 2 pyruvate + 2 ATP Where do the pyruvate go next?

Intermediary Reaction Pyruvate (3-Carbon) Acetyl (2-Carbon)-CoA 2 Pyruvate + 2 CoA + 2 NAD+  2 Acetyl-CoA + 2 CO2 + 2 NADH

Overall energy production so far… Glycolysis: 2 ATP, 2 NADH Intermediate reaction: 2 NADH

Kreb’s Cycle Squeezing the energy out of acetyl-CoA!!! Roles of the Krebs cycle Generate energy by oxidizing acetyl-CoA to carbon dioxide and water Supply biochemical intermediates for other pathways Entry point of various degradative pathways for energy generation acetyl-CoA Squeezing the energy out of acetyl-CoA!!!

Krebs Cycle Where are we? What is ATP? What is NAD? What is FAD? How much energy is produced?

FADFADH2 Flavin Adenine Dinucleotide

Energy Production from Krebs Cycle Acetyl-CoA + 3 NAD+ + ADP + Pi → 3 NADH + ATP + 2 CO2 Wait we had two pyruvates to start… have to multiply above by 2!! 2 Acetyl-CoA + 6 NAD+ + 2 ADP + 2Pi → 6 NADH + 2 ATP + 4 CO2

Energy Production So far… Glycolysis: 2ATP, 2 NADH Intermediate Step: 2 NADH Kreb’s Cycle: 2 ATP, 6 NADH, 2 FADH2 Where to next?

Electron Transport System Video Take notes and write down main points.

Electron Transport System Electron transport chains are redox reactions that transfer electrons from an electron donor to an electron acceptor. The transfer of electrons is coupled to the translocation of protons across a membrane, producing a proton gradient. The proton gradient is used to produce useful work. NADH= 3 ATP FADH2= 2 ATP

Total energy production after ETC Glycolysis: 2ATP; 2 NADH= 6 ATP Intermediate step: 2 NADH= 6 ATP Krebs: 2 ATP; 6 NADH =18 ATP; 2 FADH2 = 4 ATP 34 ATP from ETC 2 ATP from Glycolysis 2 ATP from Kreb’s directly Total ATP production= 38 ATP