Lecture 13: Aerobic Respiration Flashcards
what’re the results of this reaction?
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy
C6H12O6 is oxidized and O2 is reduced
how do we know what molecule is the most reduced?
the one with the most hydrogens
What happens to matter and energy in Glycolysis?
matter: glucose (6 carbon) is oxidized to two pyruvate (3 C)
energy: NAD+ is reduced to NADH
what happens to matter and energy in the citric acid cycle?
matter: 2 pyruvate (3C) are oxidized to CO2
energy: NAD+ and FAD are reduced to NADH and FADH2
what happens to matter and energy in oxidative phosphorylation?
matter: O2 is reduced to H2O
Energy: NADH and FADH2 are oxidized to NAD+ and FAD
Energy: oxidation energy powers phosphorylation of ATP
glycolysis
universal energy releasing pathway that occurs in the cytoplasm and in the absence of O2
3 fates of glucose if ATP levels are high
- converted to glycogen and stored in the liver
- converted to lipids for long term energy storage
- converted to a 5 C ribose for DNA and RNA
where does the 6th C in the ribose go?
released through CO2
glycolysis equation
C6H12O6 + 2ADP + Pi + NAD+ -> 2 pyruvate + 2ATP + 2 NADH
Glycolysis process
step 1-3: energy investment phase (requires 2 ATP)
stept 7 & 10: energy payoff phase releases 4 ATP for net gain of 2 ATP (substrate level phosphorylation)
Step 6: 2 molecules of NAD+ are reduced to NADH
Step 10: end product is two molecules of pyruvate
* no CO2 is released, no O2 is required
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mole and the free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis
Oxidation of pyruvate
pyruvate + NAD+ + Coenzyme A + H2O -> Acetyl CoA + NADH + H+ + CO2
what does it mean that pyruvate is decarboxylated?
release of CO2
Citric Acid Cycle
oxidation of acetyl to CO2, reduction of NAD+, FAD, phosphorylation of GDP
How many molecules of CO2 are released during one turn of the citric acid cycle?
2; one CO2 released in step 3 and one released in step 4
Describe the flow of energy in the citric acid cycle
energy is transformed by the oxidation of acetyl CoA and the reduction of NAD+ and FAD
Combustion
glucose + O2 (light and heat released)
what is the name of the first step of glucose oxidation in all cells?
glycolysis
in the stepwise release of energy, where does the energy released in the small steps go?
- reduction of NAD+ and FAD
- Phosphorylation of ADP
- Phosphorylation of GDP
what is the exact amount of the small activation energy required to begin the process of the respiration?
2 ATP
Mitochondria Structure
Dual membranes: -outer membrane and inner membrane Dual Spaces: -inner membrane space -matrix space
what are the dual membranes in the mitochondria evidence as?
of a endosymbiotic origin; an archer host engulfed a bacteria
inner membrane of mitochondria
houses the electron transport chain and ATP synthase
electron transport chain
4 protein complexes embedded in the inner mitochondrial membrane; stepwise and downward release of energy bound in NADH and FADH2; redox reactions between the electron and transport proteins transport e- and H+
Flow of energy
- from the covalent bonds of glucose to reduction of IEAs
- IEAs donate electrons to the redox reactions of the electron transport chain
- energy released from ETC is used to pump protons and create an electrochemical gradient
- the proton gradient powers the phosphorylation of ADP to ATP
chemiosmosis
- diffusion of protons across a membrane driving the synthesis of ATP
- transformation of potential energy of a proton gradient to covalent bonds of ATP
- occurs in mitochondria and chloroplasts
where is ATP synthase found?
mitochondria and chloroplasts
what happens to pyruvate in the presence/absence of O2
- presence of O2- CO2 and H2O produced
- absence of O2- lactic acid produced OR ethanol and CO2 produced
alchohol fermentation
- preceded by glycolysis
- regenerates the NAD+ required by glycolysis
- done by yeasts and some plant cells
why is beer fattening?
- it contains a lot of energy in C-H bonds
2. beer can be metabolized into lipids
alcohol fermentation equation
C6H12O6 + 2ADP + 2P(i) -> 2 ethanol + 2 CO2 +2ATP
lactic acid fermentation
- preceded by glycolysis
- regenerates. NAD+
lactic acid fermentation equation
C6H12O6 + 2 ADP + 2P(i) -> 2 lactic acid + 2ATP
what gas exits the Carboy (fermentation thing)?
CO2
what gas must not enter carboy?
O2
If O2 enters carboy what will be produced?
CO2 and H2O
