Cellular Respiration
Cellular RespirationCONVERTS ENERGY IN FOOD TO ENERGY IN ATP1CELLULAR RESPIRATION INVOLVES SEVERAL STEPSInvolves over 25 chemical reactions
Occurs in cytoplasm and mitochondria
Can be divided into three main stages:
1) Glycolysis2) The Krebs cycle3) The electron transport chain2STAGES OF CELLULAR RESPIRATION1st Stage: Glycolysis - cytoplasmanaerobic (no O2 needed)
2nd Stage: Krebs Cycle - mitochondriaaerobic (O2 needed)
3rd Stage: Electron Transport Chain - mitochondriaaerobic (O2 needed)3STAGE ONE: GLYCOLYSISDoes NOT require oxygen anaerobic
First step in cellular respiration
Occurs in cytoplasm
Occurs in ALL organisms
One glucose molecule is split to form two molecules of pyruvic acid4GLYCOLYSIS HAS 2 PHASESEnergy investment phase: 2 ATP needed to start reactionEnergy harvest phase: 4 ATP producedNet gain: 2 ATP
5STRUCTURE OF MITOCHONDRIAEnvelope has inner and outer membranes
Inner membrane:Very highly folded provides increased surface areaHas many sites where cellular respiration can occurEncloses thick fluid matrix
6STAGE TWO: THE KREBS CYCLEOccurs in matrix of inner mitochondrial membrane
Aerobic O2 needed
2 Pyruvic acid 2 Acetyl CoA + 2 CO2
2 Acetyl CoA 4 CO2 + 2 ATP
Net result: 2 ATP produced7STAGE THREE: ELECTRON TRANSPORT CHAINOccurs on inner mitochondrial membraneAlso called oxidative phosphorylation or chemiosmosisAerobicrequires O2 Electron transport chain works with H+ ions and ATP synthase (proteins in membrane) to produce ATPGenerates up to 34 ATP per original glucose molecule 8MAXIMUM ATP PER GLUCOSEGLYCOLYSIS = 2 ATPKREBS CYCLE = 2 ATPELECTRON TRANSPORT CHAIN / ATP SYNTHASE = 34 ATP 38 ATP
This production results only if O2 is present 9CELLULAR RESPIRATION
10SOME CELLS CAN HARVEST ENERGY WITHOUT OXYGEN11FERMENTATIONProcess that makes ATP without O2
ATP produced in fermentation comes entirely from glycolysis
Produces no additional ATP
When O2 is not present there is an overall net gain of 2 ATP per glucose molecule
Two major types of fermentation:
Lactic acid fermentation
Alcoholic fermentation12LACTIC ACID FERMENTATIONOccurs in muscle cells when O2 supply is too low
Cellular respiration continues but fermentation is main ATP source
Produces lactic acid - waste product
Results in muscle soreness after strenuous exercise
Relieved after O2 supply restored13LACTIC ACID FERMENTATIONCauses muscle pain and cramping
ALCOHOLIC FERMENTATIONYeast: alcoholic fermentation
Produces ethyl alcohol instead of lactic acid under anaerobic conditions
Used in brewing industry
Released CO2 makes champagne and beer bubbly
Used by bakers to make bread rise 15ALCOHOLIC FERMENTATION
FERMENTATION IN MICROORGANISMSFungi & Bacteria: produce lactic acid like muscle cells Used to flavor yogurt, some cheeses
Other fermentation processes:Soybeans soy sauceCabbage sauerkraut
17FERMENTATION IN MICROORGANISMS
Results of Fermentation