Cellular RespirationCellular RespirationGlycolysisGlycolysis

Preparatory reactionPreparatory reactionCitric acid (krebs) cycleCitric acid (krebs) cycleElectron transport chainElectron transport chain

GlycolysisGlycolysis

Occurs outside mitochondriaOccurs outside mitochondria

Breaks down glucose into two Breaks down glucose into two pyruvate moleculespyruvate molecules

Evolutionary speaking, glycolysis Evolutionary speaking, glycolysis occurs in all organisms, meaning it occurs in all organisms, meaning it probably evolved before the citric probably evolved before the citric acid cycle and the electron transport acid cycle and the electron transport chainchain

Steps in GlycolysisSteps in Glycolysis1.1. Begins when glucose is activated with two ATP molecules, Begins when glucose is activated with two ATP molecules,

the glucose splits into two C molecules known as G3P.the glucose splits into two C molecules known as G3P.2.2. G3P is then oxidized, removing electrons and H ions.G3P is then oxidized, removing electrons and H ions.3.3. The lost electrons and H ions are then accepted by NADThe lost electrons and H ions are then accepted by NAD+ +

resulting in two NADH.resulting in two NADH.4.4. G3P oxidation results in the production of 4 high-energy G3P oxidation results in the production of 4 high-energy

phosphate groups which make 4 ATP molecules, called phosphate groups which make 4 ATP molecules, called substrate-level phosphorylation.substrate-level phosphorylation.

5.5. There is a net gain of only 2 ATP molecules in glycolysis There is a net gain of only 2 ATP molecules in glycolysis because 2 of the ATP molecules are used in supplying because 2 of the ATP molecules are used in supplying energy for the reactionenergy for the reaction

6.6. What happens next depends on if OWhat happens next depends on if O22 is available or not. If is available or not. If it is available, pyruvate enters and C.R. ensues. If not, it is available, pyruvate enters and C.R. ensues. If not, fermentation occurs, and pyruvate is reduced.fermentation occurs, and pyruvate is reduced.

Preparatory ReactionPreparatory Reaction

Connects glycolysis to the citric acid Connects glycolysis to the citric acid cyclecycle

converts pyruvate to a 2-carbon converts pyruvate to a 2-carbon acetyl group and attaches it to acetyl group and attaches it to coenzyme A resulting in acetly-CoA coenzyme A resulting in acetly-CoA through a redox reaction.through a redox reaction.

The reaction occurs twice for each The reaction occurs twice for each glucose molecule glucose molecule

Citric Acid (krebs) cycleCitric Acid (krebs) cycleOccurs in the matrix of the mitochondia Occurs in the matrix of the mitochondia Sometimes called the krebs cycle because it was named for sir Sometimes called the krebs cycle because it was named for sir Hans Krebs who described the reaction in the 1930s. Hans Krebs who described the reaction in the 1930s. Begins by the addition of a 2-carbon acetyl group to a 4-carbon Begins by the addition of a 2-carbon acetyl group to a 4-carbon molecule forming a 6-carbon citric acid moleculemolecule forming a 6-carbon citric acid moleculeIn the reactions that follow, at three different times, two electrons In the reactions that follow, at three different times, two electrons and one H ion are accepted by NADand one H ion are accepted by NAD+ + , forming NADH, forming NADHAt one time in the cycle, two electrons and one H ion are accepted At one time in the cycle, two electrons and one H ion are accepted by FAD, forming FADHby FAD, forming FADH2 2

Some energy is released and is used to make ATP by substrate-Some energy is released and is used to make ATP by substrate-level phosphorylation,level phosphorylation,One high-energy metabolite accepts a phosphate group and ADP One high-energy metabolite accepts a phosphate group and ADP to ATP in the reaction.to ATP in the reaction.For each glucose molecule that goes in, the citric acid cycle turns For each glucose molecule that goes in, the citric acid cycle turns twice.twice.The products of the cycle are 4 COThe products of the cycle are 4 CO2, 2, 2 ATP, 6 NADH and 2 FADH2 ATP, 6 NADH and 2 FADH22

The electron transport chainThe electron transport chainTakes place in the cristae of the mitochondria, in which Takes place in the cristae of the mitochondria, in which electrons are passed from carrier to carrierelectrons are passed from carrier to carrierSome carriers are cytochrome molecules(complex carbon Some carriers are cytochrome molecules(complex carbon rings with iron in the center)rings with iron in the center)NADH and FADHNADH and FADH22 carry the electrons through the system carry the electrons through the systemEach time the electrons are passed on, NADH gives up its Each time the electrons are passed on, NADH gives up its electrons and becomes NADelectrons and becomes NAD+ + then picks up electrons, then picks up electrons, therefore they are reduced.therefore they are reduced.ATP is released at each redox (reduction) reactionATP is released at each redox (reduction) reactionOxygen must be present for this to work, therefore this Oxygen must be present for this to work, therefore this process is also called oxidative phosphorylationprocess is also called oxidative phosphorylationOxygen accepts electrons in the reaction and combines Oxygen accepts electrons in the reaction and combines with hydrogen ions to form water.with hydrogen ions to form water.The electrons are being delivered to the system by FADHThe electrons are being delivered to the system by FADH2, 2, at this time two ATP molecules are formedat this time two ATP molecules are formedCoenzymes and ATP in the system undergo recycling.Coenzymes and ATP in the system undergo recycling.

For Monday Nov. 10For Monday Nov. 10Study for a 20-point quiz (credit)Study for a 20-point quiz (credit)Beginning lab on CRBeginning lab on CRStudy session after school TH 11/13Study session after school TH 11/13TEST will be on Monday 11/17TEST will be on Monday 11/17Lab Report for CR will also be due on Lab Report for CR will also be due on that daythat dayHomework: complete/review the rest Homework: complete/review the rest of the notes online at of the notes online at kauscience.k12.hi.us kauscience.k12.hi.us