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