Cellular Respiration: Harvesting Chemical Energy Chapter 6

Energy Flow in Ecosystems Photosynthesis captures and store sunlight energy as glucose Cellular Respiration release energy to cell to do work.

Respiration is the complement to Photosynthesis, completing a cycle:

PHOTOSYNTHESIS AEROBIC RESPIRATION C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O SUNLIGHT Photosynthesis & Respiration The products of photosynthesis are the reactants for respiration

Controlled Uncontrolled

The Powerful Mitochondria Provide the cell with usable energy as ATP Cells with high energy demands make more mitochondria Muscle cells have very high number of mitochondria We breath to get oxygen to our mitochondria and to to rid ourselves of the carbon dioxide the mitochondria produce The blood carries these gasses to our lungs for gas exchange by diffusion The more energy you burn, the more you breath out

ATP : Cellular unit of energy ATP ADP + P i

C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O glucoseoxygen carbon dioxide water The Reaction for Respiration: The reverse of the equation for photosynthesis The carbon atoms we eat in glucose we breath out as carbon dioxide The oxygen we breath in becomes water in our bodies

Reactants and Products The carbon atoms we eat in glucose we breath out as carbon dioxide The oxygen we breath in becomes water in our bodies

Thought questions What cells have very high number of mitochondria ? Why do we breath? We breath to get _____ into our mitochondria and to get rid of the _______the mitochondria produce How do these gasses move in the body? How does your breathing relate to energy use?

GLUCOSE The common food molecule

Respiration is a three step process: In Cytoplasm: Step 1 Glycolysis –breaks glucose into 2 pyruvate molecules –Makes 2 ATP In Mitochondrion: Step 2 Krebs cycle –Completely breaks all c-c bonds –Primes the proton gradient –Makes 2 ATP Step 3 Electron transport chain –Makes ATP by chemiosmosis –Needs O 2 –Makes more ATP

3 Steps to Cellular respiration

Respiration is a controlled release of usable energy, in the form of ATP

Step 1: Glycolysis Breaks (C 6 ) glucose into 2 pyruvate (C 3 ) Breaks C-C bond Forms 2 NADH (high energy) Forms a net of 2 ATP per glucose Takes place in cytoplasm Must have 2 NAD + as reactants to run Does not release CO 2 or need Oxygen

glucose pyruvate animal cell (eukaryotic) plant cell (eukaryotic) bacterial cell (prokaryotic) GLYCOLYSIS All cells use Glycolysis even bacteria

Glycolysis: 2 ATP in for “Priming” 4 ATP out Net: 2 ATP

ATP formation by phosphate transfer Fuel Molecule with 2 P Now Fuel Molecule with 1 P P group transferred onto now a ATP

Energy tab so far: 1 Glucose: Glycolysis net: 2 ATP

3 Steps to Cellular respiration

From the cytoplasm to the mitochondria Pyruvate moves into the mitochondrion Some preparatory steps from 2 NADH (a cofactor) Form here the products go to the Krebs Cycle

The Krebs Cycle Takes place in the inner most compartment of the mitochondria Breaks all C-C bonds, uses up all the remainders of glucose Releases CO 2 Carbon dioxide that you breath out Loads cofactors NADH, FADH 2 Forms 2 ATP

Krebs Cycle

Energy tab so far: 1 Glucose: Glycolysis net: 2 ATP Krebs Cycle: 2 ATP

3 Steps to Cellular respiration

Electron Transport Chain Electron flow along inner membrane All cofactors (coenzymes) from Glycolysis, preparatory steps and Krebs go to inner membrane Cofactors release electrons, and protons Electrons flow and pump protons out creating gradient ATP made n by chemiosmosis Electrons flow to Oxygen, the final electron acceptor, and with protons form water

inner compartmentouter compartmentcytoplasm outer mitochondrial membrane inner mitochondrial membrane Mitochondrion Structure

OUTER COMPARTMENT INNER COMPARTMENT Electron transport chain Cofactors (NADH, FADH2) provide protons and fuel transport chain proton pump

Chemiosmosis by the proton gradient makes ATP from ADP + P i

Energy tab so far: 1 Glucose: Glycolysis net: 2 ATP Krebs Cycle: 2 ATP Chemiosmosis: (Electron transport chains): ATP Grand Total ATP

Why we breath: We need Oxygen to accept electrons and keep the transport chain flowing We must get rid of the excess carbon dioxide from the Krebs cycle, or our blood pH will drop too low.

We need Oxygen to:

Foods other than glucose… Catabolism: all biomolecules are broken down and feed into the pathway at different points. –Lipids –Complex carbohydrates –Proteins –Nucleic Acids

All food feeds into Respiration:

Not all cells do aerobic respiration: Some live with out oxygen (anaerobes) Some need more energy faster than the Krebs cycle can keep up (muscles under workout stress) Some environments turn off the Krebs cycle (yeasts) Bacteria do not have mitochondria These cells do Fermentation

start (Glycolysis) in cytoplasm completed in mitochondrion start (Glycolysis) in cytoplasm completed in cytoplasm Aerobic Respiration In Mitochondria Anaerobic Energy- Fermentation Mitochondria require oxygen Fermentation does not

Fermentation equations:

Fermentation Normal Glycolysis, only 2 ATP No Krebs Cycle Must regenerate NAD + or Glycolysis will stop “wastes” pyruvate energy to reform NAD + Produces either Lactic Acid (Muscles) or Ethanol and Carbon Dioxide (Yeasts). NO additional ATP

Energy Comparison: Fermentation Glycolysis 2 ATP Total 2 ATP Aerobic Respiration Glycolysis 2 ATP Krebs Cycle 2 ATP ETC ATP Total ATP

Ethanol & Carbon Dioxide Production The carbon dioxide makes the bubbles in beer and champagne!! They let it escape in wine

Ethanol & Carbon Dioxide Fermentation The ethanol bakes away, it is part of the aroma of baking bread!!

Lactic Acid Production