Redox Rxn: Transfer of Electron from One Atom to Another

Chapter 7 lecture notes

Definition of cellular respiration: catabolic pathway that harvests free energy from simple carbohydrates> we will cover

Aerobic______-

Anaerobic______

Fermentation______

Redox Rxn: transfer of electron from one atom to another

Example: NaCL

Redox rxn of Cell resp: C6H12O6 + 6O2à 6CO2 +6H2O+ energy (ATP)

·  Fuel is oxidized and oxygen is reduced. Energy of H is lowered as it is trasnfered from glucose to h2o

·  Activation energy prevents glucose from being consumed all at once.

·  Cell Resp uses a series of redox rxns to strip electrons (H) 1 by 1 from glucose and add to oxygen, releasing Energy

·  NAD+ acts as an electron acceptor (oxidizing agent)

·  NADH represents stored energy that is tapped to make ATP

·  By transferring electron to ETC.

·  Oxygen then pulls electron through ETC, pumping H+ out of mitochondria and creating electrochemical gradient.H+ then falls back through ATP synthase

Glycolysis: rearragnges the bonds of glucose (6c) into 2 molecules of pyruvate (3C)

Key terms: Glucose, pyruvate, substrate level phosphorylation

·  uses two ATP

·  Creates: 2 Pyruvate, 4 ATP, 2 NADH

·  Define: substrate-level phosphorylation: Direct transfer of Phos Group from org. molecule

·  Location: outside mitochondria

Krebs Cycle: Pyruvate enters mitochondrial matrix and is further decomposed. Electrons collected and taken to ETC

Key terms: NAD+/H

·  Pyruvate is oxidized into Acetyl CoA

·  6CO2 is released (remind of equation), 2 ATP produced (substrate level phosphorylation)

·  8 NADH, 2 FADH created (carriers of electrons that were stripped off of pyruvate)

·  Location: inside MM

ETC: Captures free energy from electrons carried by NADH and FADH in a series of coupled reactions that establish an electrochemical gradient across membranes. What does this mean?

·  Two parts: Electron transport chain and Chemiosmosis

·  electrons fall through series of membrane proteins on their way to oxygen (terminal Electron acceptor)

·  proteins work to pump hydrogen protons (H+) into inner-membrane space of mito.

o  Established a electrochemical gradient

·  Protons then fall back into matrix, powering ATP Synthase

·  Uses one O2

·  Creates: 26-28 ATP through Oxidative phosphorylation

Fermentation and anaerobic respiration

Anaerobicè has ETC, final electron acceptor is something other than oxygen

Used by prokaryotic organisms living in environments W/O oxygen

Type of cellular respiration

Fermentationè No electron transport chain, an extension of glycolysis that transfers e- from NADH to pyruvate

Harvesting energy (oxidization) without cellular respiration

Must have adequate supply of NAD+è must have a way to recycle NADH after it oxidizes

In cell resp this happens in ETC

Alcoholic fermentationè pyruvate converted to ethanol (releases CO2)

Lactic Acid fermentationè pyruvate converted to lactate (no CO2 released)

Much less efficient than aerobic respiration (only 2 ATP per cycle)

Cellular Respiration Efficiency:

Only about 34% efficient (34% of potential E in glucose is transferred to ATP)

Actually pretty efficient (good cars are only 25%)

The rest of the energy is lost as heat

Some is used to maintain high body temps (human)

Rest is dissipated through sweating or other cooling mechanisms