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Complex Organic Molecul es Simpler waste products w/ less energy catabol ic pathwa y ATP + H 2 O ADP + P

Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

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Cellular Respiration C 6 H 12 O O 2  6 CO H 2 O + E Oxidation Reduction C 6 H 12 O 6 is oxidized to form CO 2 O 2 is reduced to form H 2 O e- are used to form ATP

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Page 1: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Complex Organic Molecules

Simpler waste products w/ less energy

catabolicpathway

ATP + H2O

ADP + P

Page 2: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

LEO says GEROxidation = loss of e-

Reduction = gain of e-

Xe- + Y X + Ye- X is being oxidized

(reducing agent)

Y is being reduced

(oxidizing agent)

Page 3: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Cellular Respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + E Oxidatio

n

Reduction

• C6H12O6 is oxidized to form CO2 • O2 is reduced to form H2O• e- are used to form ATP

Page 4: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

• Enzymes lower EACT so glucose is oxidized slowly.• Hydrogens stripped from glucose are not transferred directly to oxygen, but are passed to a special e- acceptor

NAD+

Page 5: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

NAD+ (nicotinamide adenine dinucleotide)

Acts as a coenzyme in the redox reaction• functions as an oxidizing agent by trapping e-

Reactions are catalyzed by enzymes called dehydrogenases

Page 6: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

R–C–R’ + NAD+ R-C-R’ + NADH + H+

H

OH Ooxidation

reduction

NAD+ = oxidized coenzymeNADH = reduced coenzyme

dehydrogenase

Page 7: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Steps of Cellular Respiration:1. GLYCOLYSIS

• occurs in cytosol• partially oxidizes glucose (6C) into two pyruvate (3C) molecules

Energy investment phase = requires to ATP to start

Page 8: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

GLUCOSE (6C)

FRUCTOSE DIPHOSPHATE (6C)

2 PGAL

2 ATP2 ADP

Page 9: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

2 DPGA

2 NAD

2 NADH2 P

2 PGA

2 ADP2 ATP

Page 10: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

2 H2O

2 ADP2 ATP

PYRUVIC ACID

Kreb’s Cycle

Page 11: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P
Page 12: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P
Page 13: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Chemical energy from glucose is still stored in the pyruvate molecules.

Fate depends on presence or absence of oxygen

If O2 is present pyruvate enters the mitochondrion where it is completely oxidized

Page 14: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

2. KREBS CYCLE• occurs in mitochondrial matrix• complete glucose oxidation by breaking down a pyruvate derivative (acetyl Co-A) into CO2 a small amount of ATP is

produced by substrate-level phosphorylation NADH formed by transfer of e- from substrate to NAD+

Page 15: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Formation of Acetyl-CoA

C=O

C=O

CH3

OH

C=O

S-CoA

CH3

CO2

NAD+

NADH+ H+

pyruvate

Acetyl CoA

Page 16: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

A multienzyme complex catalyzes:• the removal of CO2 from the carboxyl group of pyruvate• the oxidation of the 2C fragment to acetate while reducing NAD+ to NADH• the attachment of coenzyme A to the acetyl group forming acetyl CoA

Page 17: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Krebs Cycle (Citric Acid Cycle)• oxidizes remaining acetyl

fragments of Acetyl-CoA to CO2For every turn of the Krebs cycle:

• 2 C enter in the acetyl fragment• 2 different C are oxidized and leave as CO2• coenyzymes are reduced

3 NADH and 1 FADH2• 1 ATP produced by s-l phosphorylation• oxaloacetate is regenerated

Page 18: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

(6C)

(5C)

(4C)

(4C)

(4C)

ATP

H2O

Page 19: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

It takes 2 turns of the Krebs cycle for complete oxidation of 1 glucose molecule.

Page 20: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

GDP

GTP

P+

ADP ATP

CoA-SH

CH2

CH2

C=OS-CoA

COO-

succinyl CoA

CH2

CH2

COO-

COO-

succinate

Page 21: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P
Page 22: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

3. ELECTRON TRANSPORT CHAIN• occurs at the inner

membrane of the mitochondrion• accepts energized e- from reduced coenzymes (NADH and FADH2) • O2 pulls the e- down the ETC to a lower energy state• couples the exergonic slide of e- to ATP synthesis (oxidative phosphorylation – makes 90% of all ATP)

Page 23: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

FMN

CoQFeS

FeSCyt b

Cyt c

FeS

Cyt c3

Cyt aCyt a1

½ O2

NADH FADH2

Final e- acceptor(forms

water)

NADH=3 ATPFADH2=2 ATP

Page 24: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

ETC does not make ATP directly.It generates a proton gradient across the inner mitochondrial membrane.

Page 25: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

KREBS CYCLE net: (2 turns)• 2 ATP by s-l

phosphorylation• 6 NADH• 2 FADH2• 4 CO2

*** most energy found in NADH and FADH2 in high energy bonds

From glycolysis and Krebs

Page 26: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Process ATP by S-L

Phos.

Reduced Co-

Enzyme

ATP by Ox

Phos.

TOTAL

GlycolysisNet 2 ATP 2 NADH 4-6 ATP 6-8 ATP

Oxidation of

Pyruvate2 NADH 6 ATP 6 ATP

Krebs Cycle 2 ATP

6 NADH2 FADH2

18 ATP4 ATP 24 ATP

36-38 ATPTOTAL

Page 27: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

* Prokaryotes usually get a better yield of 38 ATP because there is no membrane separating glycolysis from the ETC.* Eukaryotes usually only get 2 ATP per NADH in glycolysis.

Page 28: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Respiratory Poisons:Cyanide – blocks e- from cyt a3 to O2

Oligomycin (antibiotic) – inhibits ATP synthaseDinitrophenol (DNP) – uncouples the chemiosmotic reaction so protons leak across the membrane

Page 29: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Anaerobic Respiration:• occurs if O2 is not present there is no final

e- acceptor• used by plants, fungi (yeasts) and bacteria• occurs in the cytoplasm alongside glycolysis

Page 30: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

2 PYRUVATE

2 ACETYLALDEHYDE

2 ETHANOL

2 CO2

2 NADH2 NAD+

Page 31: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

2 PYRUVATE

2 LACTATE

2 NADH2 NAD+

Page 32: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P
Page 33: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

ANAEROBIC RESPIRATION:• does not require O2• uses ETC to make ATP• uses a substance other than O2 as the final e- acceptorex. NO3 or SO4

-2

• produces ATP by oxidative phosphorylation

** occurs in only a few bacterial groups that exist in anaerobic environments

Page 34: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

Strict (obligate) aerobes:organisms that require O2 for growth and as the final e- acceptor

Strict (obligate) anaerobes:organisms that only grow in the absence of O2, and are poisoned by it

Page 35: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

FACULATIVE ANAEROBES:organisms can grow in either aerobic or anaerobic environmentsCells can make ATP by fermentation if O2 is not available or ATP by cellular respiration if O2 is available.PYRUVATE is common to both fermentation and respiration.

Page 36: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

GLUCOSE

PYRUVATE

reduced to ethanol or lactate and NAD+ is recycled as NADH is oxidized

oxidized to acetyl CoA and oxidation continues into the Krebs cycle

no O2

O2

Page 37: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

RESPIRATION CONTROLS:• Third step in glycolysis is catalyzed by the allosteric enzyme phosphofructokinase.• Ratio of ATP to ADP reflects energy status of the cell. PFK is sensitive to changes in this ratio.• Citrate and ATP are allosteric inhibitors of PFK.

When concentration rises, enzyme slows glycolysis.

Page 38: Complex Organic Molecules Simpler waste products w/ less energy catabolic pathway ATP + H 2 O ADP + P

• ADP is an allosteric activator of PFK

so when ADP rises, enzyme speeds up glycolysis