CELL RESPIRATION

RESPIRATION Two Meanings: BREATHING OR EXTERNAL RESPIRATION CELLULAR RESPIRATION - Process by which organic compounds are broken down to yield energy for work This energy molecule is _________

Overall Equation Glucose + Oxygen ---> Carbon Dioxide + Water + Energy or C6H12O6 + 6O2 ---> 6CO2 + 6H2O + (36-38)ATP

Why is Cellular respiration Important? Two main reasons ATP is made that allows cells to carry out all its activities Carbon Dioxide produced is used by autotrophs for Photosynthesis

Where does Cellular respiration occur? In all Living cells Prokaryotic cells - in cytoplasm and inner foldings of plasma membrane Eukaryotic cell – cytoplasm and mitochondria

What are the raw materials needed Sugar (glucose) Oxygen (not always) Water

Aerobic - with oxygen, releases the most ATP per glucose molecule TYPES OF RESPIRATION Aerobic - with oxygen, releases the most ATP per glucose molecule Anaerobic - without oxygen, releases the least ATP per glucose molecule

Info About Aerobic Respiration Oxygen needed Breakdown of glucose- occurs in cytoplasm In mitochondria Krebs cycle - in the matrix Electron transport chain - in the cristae 6 carbon dioxide molecules formed 36-38 ATP molecules formed

Both Processes start with Glycolysis Glyco stands for Glucose Lysis means to Split What is Glycolysis?

Glycolysis (occurs in the cytoplasm Glucose 2 ATP 2 ADP+P 2 PGAL 4 ADP+P 2 NAD+ 4 ATP 2 NADH 2 Pyruvate

What happens Glycolysis? Occurs in the cytoplasm of all organisms. 6 Carbon Glucose splits into 2 molecules each containing 3 carbons (called pyruvate) Because Glucose is a pretty stable molecule, energy is needed to start this reaction (2ATP)

What is Glycolysis? This process generates 4 ATP and 2 NADH What is the net gain of ATP at the end of this reaction? 2

Krebs Cycle or Citric Acid Cycle Hans Krebs ( Nobel Prize) Pyruvate lysed through a series of steps to release all the carbon as Carbon dioxide. How many carbon dioxide molecules are formed? ______ What else? 2 ATP 6 NADH (+2 in the intermediate)=8 2 FADH2 (similar molecule to NADH)

Let’s Take Inventory! So far (from Glycolysis to Krebs Cycle) We have used 2 ATP We have made 4 ATP in glycolysis We have made 2 ATP in Krebs Cycle Total gain of ATP __4 How many ATP molecules do you need per minute per cell? Is this enough?

From Wikipedia.org/wik/Electron_transport_chain

Electron Transport Chain (ETC) Occurs on the mitochondrial inner membrane or cristae NADH and FADH2 release their Hydrogen atoms Hydrogen atoms breaks up into e- and H+ Electrons travel through the membrane proteins

Electron Transport Chain (ETC) Hydrogen accumulate inside the cristae Concentrations gradient drives the H+ through the ATP Synthase Energy used to make ATP (32 ATP) The hydrogen then reacts with the oxygen molecules to make H+ + O2 --> H2O Some energy lost as heat – useful to keep warm

So How many ATPs are made Glycolysis: Net gain of 2 Krebs Cycle: 2 ETC: 32-34 Note: Each NADH can make 3 ATP Each FADH2 can make 2 ATP TOTAL = 36 ATP

Anaerobic Respiration Absence of oxygen Krebs Cycle and ETC cannot function Glycolysis can occur Cell gets 2 ATP per glucose NADH builds up and will eventually stop formation of ATP Survival Tactics??

Anaerobic Respiration Lactic acid fermentation Alcoholic fermentation Yeast helps bread rise Yeast used to make alcoholic bevs Used to make gasohol Human muscle contract in low O2 In Bacteria to make cheese, yogurt, sauerkraut

2 ATP made and NADH recycled Alcoholic fermentation

2 ATP made and NADH recycled Lactic Acid Fermentation

Glucose 2pyruvate No oxygen needed (anaerobic) Many enzymes needed 4 ATPs needed, 2 ATPS made net gain of 2 ATP 2NAD 2 NADH