Lecture 6 Outline (Ch. 9) I.Overview of Respiration II.Redox Reactions III.Steps of Respiration IV.Cellular Respiration A. Glycolysis B. Coenzyme Junction C. Citric Acid Cycle (aka Krebs/TCA cycle) D. Electron Transport Chain (ETC) E. Chemiosmosis V.Anaerobic respiration VI.Respiration using other biomolecules VII.Lecture Concepts

Cellular Respiration Overall purpose: convert fuels to energy animals AND plants complementary to photosynthesis

Cellular Respiration: (Exergonic) Cellular Respiration catabolizes sugars to CO 2 requires O 2 at mitochondrion

Redox Reactions as part of chemical reaction, e- are transferred e- transfer = basis of REDOX reactions (reduction) (oxidation)

Redox Reactions follow the H, e- w/them

Redox Reactions Equation for respiration

transfer of e- to oxygen is stepwise Redox Reactions

e- moved by NAD+ (niacin) when “carrying” e- (& H+), NADH Where do e- come from? gained e- (& H+), reduced food (glucose) Where do e- go? glucose NADH ETC O 2 (H 2 O) Redox Reactions

1. glycolysis - cytosol - mitochondrial matrix - inner mitochondrial membrane Steps of respiration: 2. Citric acid cycle 3. ETC 4. Chemiosmosis - inner membrane to intermembrane space Steps of Respiration Coenzyme Junction

Stages of respiration: 1. Glycolysis – prep carbons Cellular Respiration

1. Glycolysis 1 glucose (6C)2 pyruvate (3C) key points:- inputs - NAD+/NADH - ATP Cellular Respiration - CO 2 and H 2 O - outputs eukaryotes AND prokaryotes

-inputs: CO 2 none 2 H 2 O -outputs: 1 Glucose 2 ATP 4 ATP (2 net) 2 NADH 2 pyruvate Where do they go? Glycolysis Cellular Respiration

Coenzyme Junction 2 pyruvate (3C) 2 Acetyl CoA (2C) Cellular Respiration pyruvate joins coenzyme A (vitamin B) 2 C lost (as CO 2 ) 2 NAD+  NADH

Steps of Respiration Stages of respiration: 2. Citric acid cycle e- transfer: redox

Cellular Respiration 2. Citric acid cycle 2 Acetyl CoA (2C) join oxaloacetate (4C) few ATP so far e- to carriers (NAD+, FAD) mitochondrial matrix 2 citrate (6C) converted several steps, 4C lost (CO 2 )

-inputs: 4 CO 2 H 2 O none -outputs: 2 Acetyl CoA (2C) 2 ATP 6 NADH 2 FADH 2 [2 oxaloacetate (4C)] Where do they go? Citric acid cycle

Self-Check Step of Respiration InputsOutputsCO 2 /H 2 OATP produced e- carriers loaded Glycolysis1 glucose2 pyruvate2H 2 O2 net2 NADH Coenzyme Junction Citric Acid Cycle Electron Transport Chain Oxidative phosphorylation Fermentation

1. glycolysis - cytosol - mitochondrial matrix - inner mitochondrial membrane Steps of respiration: 2. Citric acid cycle 3. ETC 4. Chemiosmosis - inner membrane to intermembrane space Steps of Respiration Coenzyme Junction

Steps of Respiration Stages of respiration: 3.ETC Proton Motive Force

Substrate-level phosphorylation Phosphate group moved from substrate to ADP  yields ATP

Cellular Respiration 3. Electron transport chain (ETC) lots of energy harvested released in stages so far, 4 ATP – substrate P oxidative phosphorylation many ATP – oxidative phosphorylation

Cellular Respiration – mitochondria revisited

Cellular Respiration ETC  e- collection molecules embedded on inner mitochondrial membrane Electron transport chain (ETC) accept e- in turn e- ultimately accepted by O 2 (O 2 reduced to H 2 O)

~100 H+ (stored) 10 H 2 O -outputs: ATP (none yet) Where do they go? H+ build up in intermembrane space (potential energy) Electron transport chain (ETC) -inputs:per glucose, 10 NADH 2 FADH 2 10 H+

Steps of Respiration Stages of respiration: 4. Chemiosmosis ATP produced!

Cellular Respiration 4. Chemiosmosis ATP synthase: inner mitochondrial membrane energy input ATP – H+ gradient chemiosmosis – ion gradient to do work

Cellular Respiration Four parts to ATP synthase: 4. Chemiosmosis H+ must enter matrix here Rotor, Stator, Rod, Knob Generates 1 ATP per ~3.4 H+

Cellular Respiration Summary of respiration Cells convert ~ 40% of energy in glucose to energy in ATP Most fuel efficient cars convert only ~ 25% of gasoline energy

Cellular Respiration - anaerobic no O 2 – no oxidative phosphorylation fermentation extension of glycolysis substrate-level phosphorylation only need to regenerate e- carrier (NAD+)

Cellular Respiration - anaerobic Types of fermentation - 1. alcohol pyruvate converted to acetaldehyde acetaldehyde accepts e- ethanol produced

Cellular Respiration - anaerobic pyruvate accepts e- lactate produced Types of fermentation - 2. Lactic acid

Cellular Respiration - anaerobic inputs/outputs alcohol lactic acid pyruvate in CO 2 and EtOH out pyruvate in lactate out brewing & baking muscle fatigue

Cellular Respiration pyruvate - junction O 2 present – citric acid cycle O 2 absent - fermentation

Self-Check Comparison of aerobic vs. anaerobic respiration: ATP made by: ATP per glucose: AerobicAnaerobic initial e- acceptor: final e- acceptor:

Cellular Respiration – other biomolecules Glucose catabolism – one option Proteins: Fats: Catabolized into a.a. – Enter diff. points – depends on a.a. Glycerol in at glycolysis - becomes pyruvate Fatty acids in before CAC - becomes Acetyl CoA Amino group removed

Self-Check Step of Respiration InputsOutputsCO 2 /H 2 OATP produced e- carriers loaded Glycolysis1 glucose2 pyruvate2H 2 O2 net2 NADH Coenzyme Junction Citric Acid Cycle Electron Transport Chain Oxidative phosphorylation Fermentation

Lecture 6 concepts -Describe in words the purpose of cellular respiration -Write the equation for cellular respiration -Given an equation, particularly that for cellular respiration, determine which molecules are oxidized and reduced -List the steps of cellular respiration and where they occur -For glycolysis, coenzyme junction, and the citric acid cycle, give inputs, outputs, ATP made/used, e- carriers loaded, water and carbon dioxide molecules produced -For the electron transport chain and chemiosmosis, give inputs, outputs, ATP made/used, e- carriers loaded, water and carbon dioxide molecules produced -Keep track of the total number of carbon molecules going in and coming out for each step of respiration -Compare substrate-level and oxidative phosphorylation -Compare the e- carriers, final e- acceptors, and ATP made for aerobic respiration and anaerobic respiration -Write out a list of new terminology and provide descriptions