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COST OF BIOSYNTHESIS FOR GROWTHON MINIMAL MEDIUM vs RICH MEDIUM
- rich medium:
- -reducing power cost for all molecules = 0
- - All energy costs are significantly less
- -energy cost for protein drops to zero
- Both:
- energy cost for 1-carbon =0
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ENERGY COST UNIT
uMOLE ~P / g CELLS
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Reducing power unit
umole NADPH/g cells
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AMPHIBOLIC PATHWAYS
REVERSIBLE PATHWAYS
COMPLEX (BRANCHING AND CONVERGING)
REQUIRE COMPLEX REGULATION(ESPECIALLY IN BACTERIA WHICH HAVE NOORGANELLES FOR COMPARTMENTATION).
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Where does glucose go in e.coli?
3 options
70 % OF THE GLUCOSE––> GLYCOLYSIS––> ORGANIC ACIDS
30% ––> PENTOSE-P PATHWAY ––> RIBOSE––> NUCLEIC ACIDS.
A SMALL AMOUNT OF THE PYRUVATE ––> BRANCHING PATHWAY ––> SUCCINATE, á-KETOGLUTARATE
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ANPLEUROTIC REACTIONS
REPLENISHES METABOLITES DRAINED BY PATHWAYS
“INTERCONNECTING, REVERSING OR BYPASSING REACTIONS”
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ANAEROBIC GROWTH ON GLUCOSE
- PEP CARBOXYLASE (same as for aerobic)
- PYUVATE FORMATE LYASE
- TRANSAMINASE
- ASPARTASE
- FUMARATE REDUCTASE
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What are the end products of anaerobic Krebs cycle?
- Succinyl CoA
- Glutamate (from
 -ketoglutarate)
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PEP CARBOXYLASE
PEP + CO2 ––> OXALOACETATE (PM) + Pi
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PYUVATE FORMATE LYASE (ANAEROBIC ENZYME)
PYRUVATE + CoA ––> ACETYL-CoA + FORMATE (HCOO-)
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TRANSAMINASE
OXALOACETATE + GLUTAMATE ––> ASPARTATE + -KG
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ASPARTASE (ANAEROBIC)
ASPARTATE ––> NH4+ + FUMARATE
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FUMARATE REDUCTASE
Anaerobic or Aerobic?
What is its counterpart?
What is the reaction?
Anaerobic
Succinate Dehydrogenase
FUMARATE + NADH <––> SUCCINATE + NAD
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SUCCINATE DEHYDROGENASE
Anaerobic or Aerobic?
What is its counterpart?
What is the reaction?
Aerobic
Fumerate Reductase
FUMARATE + FADH <––> SUCCINATE + FAD
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GLUCONEOGENESIS
REVERSAL OF GLYCOLYSIS FOR SUGARS, CELL WALL, NUCLEIC ACIDS,
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WHAT IS THE MAJOR GLUCONEOGENIC REACTION?
WHY?
- PEP CARBOXYKINASE
- -it is the first reaction in the pathway.
- -occurs in mitochondria with the formation of oxaloacetate by the carboxylation of pyruvate
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PEP CARBOXYKINASE
OAA + ATP ––> PEP + ADP+ CO2
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MALIC ENZYMES (TWO)
What are they?
What is the reaction?
What is it used for?
NAD MALIC ENZYME AND NADP MALIC ENZYME
MALATE + NAD(P)––> PYRUVATE + NAD(P)H+ CO2 P
USED TO PRODUCE ACETYL-CoA FOR KREBS CYCLE AND FOR LIPID SYNTHESIS
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PEP SYNTHASE
Aerobic or Anaerobic?
required for what?
what is the reaction?
- Aerobic
- REQUIRED FOR GROWTHON PYRUVATE (3C) – NOTTOO IMPORTANT FOR 4C
PYR + ATP ––> PEP + AMP+ Pi
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FRUCTOSE DIPHOSPHATASE
Aerobic or Anerobic?
What is the reaction
- Aerobic
- F1,6DP ––> F-6P + Pi
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GROWTH ON 3C COMPOUNDS
3 Enzymes - purpose
PEP SYNTHASE FOR GLUCONEOGENSIS.
PYRUVATE DEHYDROGENASE––> ACETYL-CoA FOR THE KREBS CYCLE
PEP CARBOXYLASE ––>OAA FOR THE KREBS CYCLE
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GLYOXYLATE
required for what?
What is the reaction?
2C REQUIRES THE GLYOXYLATE PATHWAY TO PRODUCE 4C FOR GLUCONEOGENSIS BY PEPCARBOXYKINASE
ISOCITRATE (6C)+ ACETYL- CoA (2C)––> MALATE(4C) + SUCCINATE(4C)
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GROWTH ON CARBOHYDRATES (SUGARS):
GLYCOLYSIS ----> ATP
ATP + ATPase ----> ENERGISED MEMBRANE ( H+)
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GROWTH ON NON CARBOHYDRATES
(ORGANIC ACIDS LIKE MALATE, PYRUVATE, ACETATE; AMINO ACIDS; FATS; NUCLEIC ACIDS):
KREBS (TCA) CYCLE ----> ATP AND REDUCING POWER(E.G. NADH)
REDUCING POWER ----> ELECTRON TRANSPORT CHAIN(ETC) ----> ENERGISED MEMBRANE
ENERGISED MEMBRANE ( H+) + ATPase ----> ATP
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