Transcript Cellular Respiration

*Not actual electric plug. For illustrative purposes only.
CELLULAR RESPIRATION
Chapter 9
Getting energy out of glucose!
Adenosine Triphosphate (ATP)
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Adenine + ribose + phosphates
Energy stored in high energy bonds between
phosphates (typically last bond used)
RNA
Nucleotide!
(+ 2 Pi)
ATP = source of energy in cell
Energy
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+
(H /electron)
carriers
NAD+/NADH, FAD+/FADH2, NADP+/NADPH
Can gain & lose hydrogen and electrons
Remember: H for HIGH ENERGY!
Oxidation & Reduction
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Oxidizing a molecule
decreases the amount of
energy in the molecule
 Remove
H, remove
electrons, add oxygen
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Reducing a molecule
increases the amount of
energy in the molecule
 Add
H, add electrons,
remove oxygen
Cellular Respiration
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Releasing energy stored in glucose
Used to charge up ATP (for cell to use)
Series of reactions (can’t release all at once)
 Glycolysis,
Fermentation (anaerobic repiration)
 Glycolysis, Krebs Cycle, Electron Transport Chain
Glycolysis
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Decomposition of glucose to
pyruvic acid (pyruvate)
Releasing some of the stored
energy from glucose
Occurs in cytoplasm
Requires input of 2 ATP
Charges up 2 NADH
Charges up 4 ATP
Net: 2 NADH & 2 ATP
PGAL = G3P
INVESTMENT
PHASE
ENERGY
HARVESTED
Aerobic vs. Anaerobic
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Aerobic = in presence of oxygen
 Pyruvate
travels to mitochondria for cellular respiration
 More ATP can be generated via Krebs & ETC
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Anaerobic = no oxygen present
used to regenerate NAD+
 No additional ATP made, but allows Glycolysis to
continue
 Pyruvate
Cellular Respiration (aerobic)
Mitochondrion
Krebs Cycle
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Remaining energy extracted
from pyruvate
Exhale CO2 as waste
Occurs in matrix of
mitochondria
Generates ATP
Generates NADH & FADH2,
will go to Electron Transport
Chain to generate ATP
Preprocessing Step (before Krebs)
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Energy required to transport into mitochondria
Oxidation of pyruvate to acetyl-CoA
Generates 1 NADH & 1 CO2
Krebs Cycle (Citric Acid Cycle)
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Acetyl-CoA + OAA → citric acid
Citric acid → OAA
 Series
of oxidizing reactions
 CO2 exhaled as waste product
 Generates ATP
 Generates NADH & FADH2
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OAA rengenerated to accept
new acetyl-CoA
Electron Transport Chain
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Uses energy from NADH & FADH2 to generate ATP
Occurs in inner mitochondrial membrane
Chemiosmosis (proton gradient & ATP synthase)
Oxygen is final electron acceptor (generates water)
Substrate Level vs. Oxidative Phosphorylation
ATP Accounting
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Each NADH → 3 ATP & each FADH2 → 2 ATP
Glycolysis
2 ATP (substrate level phosphorylation)
 2 NADH → 4 ATP (oxidative phosphorylation in ETC)
costs 2 to transport pyruvate into mitochondria!
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Pyruvate → acetyl-CoA
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2 NADH → 6 ATP (oxidative phosphorylation in ETC)
Krebs Cycle
2 ATP (substrate level phosphorylation)
 6 NADH → 18 ATP (oxidative phosphorylation in ETC)
 2 FADH2 → 4 ATP (oxidative phosphorylation in ETC)
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TOTAL THEORETICAL: 36 ATP (actual ~30 ATP)
Fermentation
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Anaerobic: in ABSENCE of oxygen
No electron acceptor at the end of ETC
 NADH accumulates, NAD+ depleted
 Krebs & glycolysis stop w/o NAD+
 No ATP production (will cause cell death)
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Regenerates NAD+ so that glycolysis can continue
Fermentation produces NO ATP
 Glycolysis uses NAD+ to produce 2 ATP
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Occurs in cytoplasm (alongside glycolysis)
2 types: Alcohol & Lactic Acid
Alcohol Fermentation
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Occurs in plants, fungi (yeast), & bacteria
Produces CO2, NAD+, and ethyl alcohol (ethanol)
Lactic Acid Fermentation
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Produces NAD+ and lactic acid (lactate)
In animals, most lactate is transported to the liver
(converted to glucose when extra ATP available)
Fermented Beverages
Respiration of
other molecules
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Cell can respire proteins
and fats when sugars are
not readily available
Proteins are broken down to
create pyruvate, acetylCoA, or other Krebs
intermediates; ammonia
(NH3) is generated as waste
Fats are broken down into
G3P and acetyl-CoA