Topics 2.8 & 8.2

Energy “batteries” of the cell Energy “batteries” of the cell sugars.phtml

Energy is released from ATP when it is converted to ADP Energy is released from ATP when it is converted to ADP

Transfer of a phosphate group (PO 4 3- ) to a molecule Transfer of a phosphate group (PO 4 3- ) to a molecule Makes molecule that gained the phosphate group less stable Makes molecule that gained the phosphate group less stable ylation.html

Chemical reactions that transfer electrons from one substance to another Chemical reactions that transfer electrons from one substance to another dox.html

The loss of electrons The loss of electrons Ex. Glucose is oxidized during cellular respiration Ex. Glucose is oxidized during cellular respiration

The acceptance of electrons The acceptance of electrons Ex. Oxygen is reduced during cellular respiration Ex. Oxygen is reduced during cellular respiration

The controlled release of energy from organic compounds in cells to form ATP.

 Glycolysis  Link Reaction  Krebs cycle  Electron Transport chain

When your cells break bonds and release energy, they control the reaction by using electron carriers (hydrogen carriers) to carry them around. When your cells break bonds and release energy, they control the reaction by using electron carriers (hydrogen carriers) to carry them around. Low Energy  High energy Low Energy  High energy + high energy e - + H + (Hydrogen ion)

low energy  high energy NAD +  NADH + H + FAD  FADH 2

Glyco = Glucose Glyco = Glucose Lysis = Slipt Lysis = Slipt

Occurs in the cytosol Occurs in the cytosol All cells have cytosol All cells have cytosol All cells undergo glycolysis All cells undergo glycolysis

Does not require O 2 Does not require O 2 2 ATP required 2 ATP required

Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate H H H H H OH HO CH 2 OH H H H H O H OH HO OH P CH 2 O P H O H HO H CH 2 OH P O CH 2 O O P HO H H OH O P CH 2 C O CH 2 OH H C CHOH CH 2 O O P ATP ADP Hexokinase Glucose Glucose-6-phosphate Fructose-6-phosphate ATP ADP Phosphoglucoisomerase Phosphofructokinase Fructose- 1, 6-bisphosphate Aldolase Isomerase Glycolysis CH 2 OH Oxidative phosphorylation Citric acid cycle Figure 9.9 A

2 NAD + NADH H + Triose phosphate dehydrogenase 2 P i 2 P C CHOH O P O CH 2 O 2 O–O– 1, 3-Bisphosphoglycerate 2 ADP 2 ATP Phosphoglycerokinase CH 2 OP 2 C CHOH 3-Phosphoglycerate Phosphoglyceromutase O–O– C C CH 2 OH H O P 2-Phosphoglycerate 2 H 2 O 2 O–O– Enolase C C O P O CH 2 Phosphoenolpyruvate 2 ADP 2 ATP Pyruvate kinase O–O– C C O O CH Pyruvate O Figure 9.8 B

Glycolysis consists of two major phases Glycolysis consists of two major phases Energy investment phase Energy investment phase Energy payoff phase Energy payoff phase Glycolysis Citric acid cycle Oxidative phosphorylation ATP 2 ATP 4 ATP used formed Glucose 2 ATP + 2 P 4 ADP + 4 P 2 NAD e H + 2 NADH + 2 H + 2 Pyruvate + 2 H 2 O Energy investment phase Energy payoff phase Glucose 2 Pyruvate + 2 H 2 O 4 ATP formed – 2 ATP used 2 ATP 2 NAD e – + 4 H + 2 NADH + 2 H + Figure 9.8

Involves phosphorylation, lysis, odixation & reduction, and ATP formation

Occurs in cytoplasm Occurs in cytoplasm 2 ATP’s are used 2 ATP’s are used 4 ATP’s are produced 4 ATP’s are produced Involves phosphorylation, lysis, odixation & reduction and ATP formation Involves phosphorylation, lysis, odixation & reduction and ATP formation When 2 molecules of NAD + are reduced, 2 molecules of NADH are produced. The intermediate carbon compound gets oxidized. When 2 molecules of NAD + are reduced, 2 molecules of NADH are produced. The intermediate carbon compound gets oxidized. Two pyruvate molecules present at end of pathway. Two pyruvate molecules present at end of pathway.

“Glucose, a six carbon sugar, is split into two three-carbon sugars. These smaller sugars are then oxidized (as NAD + is reduced) and their remaining atoms rearranged to form two molecules of pyruvate.” “Glucose, a six carbon sugar, is split into two three-carbon sugars. These smaller sugars are then oxidized (as NAD + is reduced) and their remaining atoms rearranged to form two molecules of pyruvate.”

Glycolysis releases less than 25% of the energy stored in glucose. Glycolysis releases less than 25% of the energy stored in glucose. Most of the energy is still stored in the two pyruvate molecules Most of the energy is still stored in the two pyruvate molecules

Glucose CYTOSOL Pyruvate No O 2 present Fermentation O 2 present Cellular respiration Ethanol or lactate Acetyl CoA MITOCHONDRION Citric acid cycle Figure 9.18

Occurs in the mitochondria Occurs in the mitochondria Pyruvate is moved into the mitochondrial matrix through active transport Pyruvate is moved into the mitochondrial matrix through active transport

 Carboxyl group (---COO - ) is removed a)CO 2 is released as a waste product  Two-carbon fragment is oxidized a)Compound formed is acetate b)Extracted electrons added to NAD +  Coenzyme A is added a)Compound is Acetyl CoA

This “link reaction” links glycolysis with the Kreb’s cycle. This “link reaction” links glycolysis with the Kreb’s cycle. Reaction controlled by enzymes Reaction controlled by enzymes Can be derived from most carbohydrates and fats Can be derived from most carbohydrates and fats Will be synthesized into a lipid for storage if ATP levels are high Will be synthesized into a lipid for storage if ATP levels are high

Amino acids Sugars Glycerol Fatty acids Glycolysis Glucose Glyceraldehyde-3- P Pyruvate Acetyl CoA NH 3 Citric acid cycle Oxidative phosphorylation Fats Proteins Carbohydrates Figure 9.19

Starts with Acetyl CoA Starts with Acetyl CoA Per turn (molecule of Acetyl CoA) it will produce: Per turn (molecule of Acetyl CoA) it will produce: 2 CO 2 molecules 2 CO 2 molecules 4 charged electron carriers 4 charged electron carriers 3 NADH molecules 3 NADH molecules 1 FADH 2 molecule 1 FADH 2 molecule 1 ATP molecule 1 ATP molecule

1. Acetyl CoA combines with 4-carbon compound (oxaloacetate) to form a 6-carbon compound (citrate)

1

 Acetyl CoA combines with 4-carbon compound (oxaloacetate) to form a 6-carbon compound (citrate)  Citrate is oxidized and decarboxylated to form a 5-carbon compound  CO 2 is released  NAD+ is reduced to NADH (NADH is produced)

1 2

 Acetyl CoA combines with 4-carbon compound (oxaloacetate) to form a 6-carbon compound (citrate)  Citrate is oxidized to form a 5-carbon compound  5-carbon compound is oxidized and decarboxylated to form a 4-carbon compound  CO 2 is released  NADH is produced

3 1 2

 Acetyl CoA combines with 4-carbon compound (oxaloacetate) to form a 6-carbon compound (citrate)  Citrate is oxidized to form a 5-carbon compound  5-carbon compound is oxidized and decarboxylated to form a 4-carbon compound  4-carbon compound is changed back into starting 4-carbon compound  NADH is produced  FADH 2 is produced  ATP is produced

4 molecules of ATP produced 4 molecules of ATP produced 10 molecules of NADH 10 molecules of NADH 2 molecules of FADH 2 2 molecules of FADH 2 6 molecules of CO 2 6 molecules of CO 2

An overview of cellular respiration An overview of cellular respiration Figure 9.6 Electrons carried via NADH Glycolsis Glucose Pyruvate ATP Substrate-level phosphorylation Electrons carried via NADH and FADH2 Citri c acid cycl e Oxidative phosphorylation: electron transport and chemiosmosis ATP Substrate-level phosphorylation Oxidative phosphorylation Mitochondrion Cytosol

What might this term mean? What might this term mean? ADP is phosphorylated to produce ATP, using energy released by oxidation of electron carriers (NADH & FADH 2 ) ADP is phosphorylated to produce ATP, using energy released by oxidation of electron carriers (NADH & FADH 2 )

H2OH2O O2O2 NADH FADH2 FMN FeS O FAD Cyt b Cyt c 1 Cyt c Cyt a Cyt a 3 2 H  2 I II III IV Multiprotein complexes Free energy (G) relative to O 2 (kcl/mol) Figure 9.13

If electron transfer is not stepwise If electron transfer is not stepwise A large release of energy occurs A large release of energy occurs As in the reaction of hydrogen and oxygen to form water As in the reaction of hydrogen and oxygen to form water (a) Uncontrolled reaction Free energy, G H2OH2O Explosive release of heat and light energy Figure 9.5 A H / 2 O 2

Proteins* are embedded in inner mitochondrial membrane and cristae membranes Proteins* are embedded in inner mitochondrial membrane and cristae membranes Each molecule is slightly more electronegative Each molecule is slightly more electronegative NADH and FADH 2 in the matrix are oxidized and release hydrogen atoms, which are split into H + and e -. NADH and FADH 2 in the matrix are oxidized and release hydrogen atoms, which are split into H + and e -. As e - flow down the electron transport chain, H + is pumped across the membrane into the inter membrane space As e - flow down the electron transport chain, H + is pumped across the membrane into the inter membrane space H + concentration gradient is created H + concentration gradient is created * One molecule is not a protein (coenzyme Q)

Electrons flow down the “electron transport chain” Electrons flow down the “electron transport chain” Oxygen is the final electron acceptor Oxygen is the final electron acceptor Oxygen is reduced as it gains electrons Oxygen is reduced as it gains electrons Then H + in the matrix combine with the reduced oxygen, forming water (H 2 O) Then H + in the matrix combine with the reduced oxygen, forming water (H 2 O) By using up H + in the matrix, this process further maintains the H + concentration gradient. By using up H + in the matrix, this process further maintains the H + concentration gradient.

H + flow down their gradient and move through ATP synthase H + flow down their gradient and move through ATP synthase ATP synthase uses the energy of the hydrogen ions to create phosphorylate ADP into ATP. ATP synthase uses the energy of the hydrogen ions to create phosphorylate ADP into ATP.

ATP synthase ATP synthase Is the enzyme that actually makes ATP Is the enzyme that actually makes ATP INTERMEMBRANE SPACE H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ P i + ADP ATP A rotor within the membrane spins clockwise when H + flows past it down the H + gradient. A stator anchored in the membrane holds the knob stationary. A rod (for “stalk”) extending into the knob also spins, activating catalytic sites in the knob. Three catalytic sites in the stationary knob join inorganic Phosphate to ADP to make ATP. MITOCHONDRIAL MATRIX Figure 9.14

Peter Mitchell proposed the chemiosmotic theory in 1961, but it wasn’t widely accepted at first. Peter Mitchell proposed the chemiosmotic theory in 1961, but it wasn’t widely accepted at first. He won the Nobel prize for Chemistry in He won the Nobel prize for Chemistry in

New technique to allow 3D images of the cristae to be made. New technique to allow 3D images of the cristae to be made. “The cristae are not simple infoldings … the membranes are not only very flexible but also dynamic, undergoing fusion and fission in response to changes in metabolism and physiological stimuli.” – Dr. Carmen Mannella “The cristae are not simple infoldings … the membranes are not only very flexible but also dynamic, undergoing fusion and fission in response to changes in metabolism and physiological stimuli.” – Dr. Carmen Mannella

ProcessATP usedATP producedNet ATP gain Glycolysis242 Krebs cycle022 Oxidative Phosphorylatio n: Electron transport chain and chemiosmosis 032* Total238*36*

Cellular respiration yields between 30 and 38 ATP depending on: Cellular respiration yields between 30 and 38 ATP depending on: Which electron carriers are used (FADH 2 or NADH) Which electron carriers are used (FADH 2 or NADH) Energy required to transport pyruvate into the mitochondria Energy required to transport pyruvate into the mitochondria Some hydrogen ions diffusing without going through ATP synthase Some hydrogen ions diffusing without going through ATP synthase

There are three main processes in this metabolic enterprise There are three main processes in this metabolic enterprise Electron shuttles span membrane CYTOSOL 2 NADH 2 FADH 2 2 NADH 6 NADH 2 FADH 2 2 NADH Glycolysis Glucose 2 Pyruvate 2 Acetyl CoA Citric acid cycle Oxidative phosphorylation: electron transport and chemiosmosis MITOCHONDRION by substrate-level phosphorylation by substrate-level phosphorylation by oxidative phosphorylation, depending on which shuttle transports electrons from NADH in cytosol Maximum per glucose: About 36 or 38 ATP + 2 ATP + about 32 or 34 ATP or Figure 9.16

When oxygen is not available to be the final electron reciever.