Ch 7 Cellular respiration

What is the equation for photosynthesis? What do plants need? What do plants make? If this is what plants do to make sugar… what do we do once we’ve eaten that sugar? What do YOU need? What do YOU make?

7-1: Glycolysis and fermentation Cellular respiration: complex process by which cells make ATP by breaking down organic compounds Heterotrophs must do this to obtain energy Do autotrophs? Yup!

Overview

Overview The products of photosynthesis are the reactants for cellular respiration The products of cellular respiration are the reactants for photosynthesis

Cellular respiration A process with options Glycolysis always happens first What happens next depends on Oxygen Or… Oxygen present: Aerobic respiration Oxygen not present: Anaerobic respiration

Page 132 Copy figure 7-2 in your notebooks. Be sure to include labels

Glycolysis 6-C Glucose broken into 2 3-C Pyruvic acid In the process we invest: 2 ATP In the process we create: 4 ATP 2 NADH NADH? Familiar? Another high energy electron shuttle This is an ANAEROBIC process (?) Does not require oxygen

What happens next depends on oxygen… Aerobic respiration If Oxygen present, Pyruvic acid broken down to produce more NADH NADH is used to make ATP Anaerobic respiration (fermentation) If oxygen is not present, Pyruvic acid enters another cycle Combination of glycolysis and anaerobic fermentation is called fermentation

Fermentation When oxygen is not present (anaerobic conditions) Pyruvic acid converted to other compounds In cytoplasm Fermentation: Glycolysis + regeneration of NAD+ Does not produce ATP Fermentation reproduces NAD+ so ATP can be gained through continual glycolysis If NAD+ not regenerated  no glycolysis  no ATP

Alcoholic fermentation Pyruvic acid converted to ethanol yeast bacteria Bread Wine, beer

Lactic acid fermentation Pyruvic acid converted to Lactic acid Cheeses Yogurt Cultivated dairy products Makes muscles sore after strenuous workout

Review Glycolysis Fermentation (oxygen not present) Glucose  2x pyruvic acid, 2 NADH, & 2 ATP Fermentation (oxygen not present) Alcoholic Pyruvic acid  ethanol + NAD+, & CO2 Lactic acid Pyruvic acid  lactic acid + NAD+

Aerobic respiration Pathway of cellular respiration that requires oxygen Produces 20 times more ATP than glycolysis alone Two major stages (both occur in the mitochondria) Krebs cycle Electron transport chain

Mitochondria Pyruvic acid (from glycolysis) diffuses into mitochondrial matrix Krebs  Mit. Matrix ETC  Inner membrane

Before krebs Pyruvic acid converted to acetyl CoA in matrix Releases CO2 Creates NADH

Krebs cycle Acetyl CoA combines with oxaloacetate to form citric acid Citric acid is broken down two times Each time we break off a piece from citric acid, we make: CO2, NADH, and FADH2 (same function as NADH)

So far we have made… A bunch of high energy electron carriers NADH (glycolysis and krebs) FADH2 (Krebs) A little ATP (glycolysis[2] and krebs[2]) CO2 (krebs) But the whole point of cellular respiration is to make ATP So… now we turn to the……

Electron transport chain Series of proteins that transfer electrons Location: inner mitochondrial membrane H+ and e- removed from NADH and FADH2 in the presence of O2 to make ATP

ETC H+ and e- removed from NADH and FADH2 e- moved through chain & lose energy Energy used to pump H+ from matrix into inner membrane space Creates concentration gradient of H+ across inner mebrane Gradient used to make ATP as H+ move through ATP synthase O2 is final e- acceptor at end of ETC e- + H+ +O2 = H2O

Importance of Oxygen ATP can only be made as long as e- move through ETC w/o oxygen, e- transport stops

Efficiency of aerobic respiration Number of ATP produced in Aerobic vs anaerobic respiration: Aerobic respiration Fermentation (anaerobic respiration)

Efficiency of aerobic respiration Number of ATP produced in Aerobic vs anaerobic respiration: Aerobic respiration 38 (glycolysis + krebs + ETC) Fermentation (anaerobic respiration) 2 (glycolysis only)

Summary of cellular respiration Draw figure 7-14 on page 143 Fill in table below Reaction Inputs Outputs Location Gylcolysis Pyruvic acid  acetyl CoA Krebs ETC

Anaerobic pathway: Input Output Example organism Lactic acid fermentation   Alcoholic fermentation