CELLULAR RESPIRATION II How Cells Obtain Energy to Sustain Life

CELLULAR RESPIRATION Three Major Phases: Glycolysis Krebs Cycle 3. Electron Transport Chain

CELLULAR RESPIRATION BEGINS IN THE CYTOPLASM Glucose Metabolism (first part of respiration): Starts in cytoplasm of cells of all organisms Aerobic & Anaerobic Glycolosis Lysis = break down Glyco = prefix for sugar

THE GLYCOLYTIC PATHWAY Energy Input: ATP

THE GLYCOLYTIC PATHWAY End product: 2 pyruvate molecules (Energy Output) ATP Reduced Helper NADH

SUMMARY OF GLYCOLYSIS Glycolysis: One Glucose molecule (6 C) is transformed into two (3 C) organic molecules called “pyruvate”

SUMMARY OF GLYCOLYSIS Additionally, the Enzyme Mediated Reactions of Glycolysis Yield: ATP molecules Reduced Helper (NADH) (NAD+ + H & 2e-  NADH) ***NOTE: NADH is a high energy e- carrier that will become important later!***

TWO PATHWAYS FOLLOWING GYLCOLYSIS In Absence of Oxygen: Anaerobic Respiration In Presence of Oxygen: Aerobic Respiration

FERMENTATION In Absence of Oxygen: Energy production occurs through Fermentation Occurs in cytoplasm Only yields 2 ATP per glucose but occurs fast

TWO PATHWAYS AFTER GLYCOLYSIS In Presence of Oxygen: Aerobic Respiration

AEROBIC RESPIRATION OCCURS IN MITOCHONDRIA Transition Reactions: Mitochondrial membrane Krebs Cycle: Mitochondrial matrix Electron Transport Chain: Inner membrane of mitochondria

THE TRANSITION REACTIONS Pyruvate converted into Acetyl-CoA Reduced helper (NADH) produced CO2 produced

KREBS CYCLE We Continue a Series of Redox Reactions During Krebs Cycle

SUMMARY OF KREB’S CYCLE Kreb’s Cycle: 2 acetyl Co A produce: Reduced helpers ATP CO2

OVERVIEW SO FAR… During Glycolysis, Transition Reactions & Krebs: Organic molecules are oxidized Eventually all C in glucose is found in CO2 Helper Molecules Reduced NAD+  NADH FAD  FADH2 Very little ATP produced

SUMMARY OF AEROBIC RESPIRATION

SUMMARY OF AEROBIC RESPIRATION SO FAR…..

ELECTRON TRANSPORT CHAIN In the last phase of cellular respiration, electrons are donated to proteins in the mitochondrial inner membrane

ELECTRON TRANSPORT CHAIN ETC occurs at mitochondrial inner membrane Helper molecules donate e-s to proteins embedded in membrane

ELECTRON TRANSPORT CHAIN ETC: Series of Redox Reactions where: Proteins pass e-s down chain Ea. protein is more electronegative than preceding Oxygen is final e- acceptor Water forms when Oxygen combines with electrons & 2 H+ e-

ELECTRON TRANSPORT CHAIN Some Proteins: Carry electrons (only) Carry electrons while pumping protons: H+ H+ pumped from matrix  inter- membrane space Creates electrochem. gradient

ELECTRON TRANSPORT CHAIN Electrochemical Gradient: Source of power for ATP synthesis! High H+ Low H+

ELECTRON TRANSPORT CHAIN ATP SYNTHESIS: ATP synthesis is coupled to diffusion of H+ through ATP Synthase

ELECTRON TRANSPORT CHAIN ATP Synthesis: H+ returns to matrix (moving down its gradient) ATP synthase attaches inorganic phosphate to ADP “Oxidative Phosphorylation” ATP produced!

ELECTRON TRANSPORT CHAIN

CELLULAR RESPIRATION Most ATP is Synthesized During the ETC

CONCLUSIONS: CELLULAR RESPIRATION Cellular (aerobic) Respiration: Involves series of redox reactions that release energy for ATP synthesis Begins with breakdown of sugar and ends with ATP synthesis through ATP Synthase By products include: H2O & CO2

METABOLISM OF MACROMOLECULES IS TIED TO CELLULAR RESPIRATION In absence of carbs, other molecules can be used to produce chemical energy: Proteins Fats