3. Metabolism and Energies Flashcards
Anabolism vs. Catabolism
Anabolism
- Anabolism: production of macromolecules.
from “building blocks” and energy (ATP). Reducing power is provided by NAD(P)H + H+.
- Catabolism: generation of energy (ATP) and reducing power (NAD(P)H + H+)
from nutrients. By-products of catabolism may be used as precursor molecules for anabolism.
Essential elements
C,O,N,H,P,S,Se
Defined medium vs. Complex medium
- Defined medium: know exactly what’s in it
- Complex medium: don’t know the proportion inside
Fastidious organism
nutritionally demanding, complex nutritional requirement.
because they are lack of some metabolic passkey so there is no production of certain AA, purines or pyrimidines.
negative/positive free energy means release/absorb energy?
(-)delta G0’ release E
(+) delta G0’ absorbs E
oxidation/reduction
lose/gain e-?
oxidation lose e-
reduction gain e-
redox couples(2H+/ H2) oxidized form/reduced electron receptor/ electron donar
NAD+ oxidized
NADH reduced
three basic catabolic pathways are all that is required to produce all of the precursors needed for anabolism (carbon compounds and energy)?
– Glycolytic pathway (glycolysis, Embden-Meyerhof pathway).
– Pentose phosphate pathway (hexose monophosphate pathway)
– Tricarboxylic acid pathway (TCA; citric acid cycle, Krebs cycle)
Fermentation vs. Respiration
– Fermentation: organic compounds are Electron Donors and electron acceptors. ATP is produced by substrate- level phosphorylation.
– Respiration: organic compounds are oxidized to CO2 with O2 (or substitute) as the Electron Acceptor. Most of the ATP is produced by oxidative phosphorylation.
In Glycolytic pathway (Glycolysis), 1 molecule of glucose is oxidized to yield how many pyruvates, ATP, NADH?
ATP is produced by?
- 1 mole glucose–>2 moles pyruvates, 2 ATP, and 2NADH + H+
- substrate-level phosphorylation
In TCA cycle, pyruvate is oxidized to?
- first oxidized to Acetyl-CoA and CO2 by pyruvate dehydrogenase,
then enters the cycle to be fully oxidized to CO2 and H2O
Succinate dehydrogenase is located at?
in the membrane
Why Oxaloacetate must be generated?
products of reaction is the reactants of next reaction, So lack of Oxalacetate—cycle can NOT proceed
In 1 turn of TCA cycle, besides the complete oxidation of acetyl group to acetyl-CoA, how many CO2, GTP, NADH, FADH2 is produced?
2 CO2
1 GTP
3NADH
1FADH2
before pyruvate enter TCA cycle, it produce?
1 NADH and 1CO2
use of NADH+H+ and FADH2
More ATP can be produced from NADH+H+ and FADH2; their oxidation is coupled to the reduction of a terminal electron acceptor – a process called respiration – and the energy released is used to drive the synthesis of ATP.
Aerobic respiration vs. Anaerobic respiration
•Aerobic respira0on: O2 is the terminal electron acceptor.
• Anaerobic respira0on: other compounds act as terminal electron acceptors, under anoxic
condi0ons.
Respiratory chain
series of hydrogen and electron carriers that can undergo oxida0on-reduc0on.
When a reduced substrate is oxidized (NADH+H+), the hydrogens are transferred to…. ?
- hydrogen carrier (FMN).
The hydrogens are then transferred to the next carrier in the sequence.
If the next carrier is an electron carrier, what will be accepted?
- only the electrons will be accepted and the protons will be released to the outer phase. Then, if the next carrier is a hydrogen carrier, two protons must be taken from the inner phase.
At complex 4, how many electrons and protons from the inner phase are used to reduce oxygen to water?
2 e- and 2 H+
Oxygen is the final electron acceptor.
Complex I
NADH dehydrogenase, FMN (hydrogen carrier), Fe-S center (electron carrier).
Q: quinone,
hydrogen carrier.
Complex II: succinate dehydrogenase, FAD
Hydrogen carrier
succinate dehydrogenase, FAD
Hydrogen carrier
Complex III
cytochrome bc1, Fe-S (electron carriers).
Cytochrome c
electron carrier.
Complex IV
electron carrier, terminal
oxidase.
In E. coli, only__protons per NADH+H+ and __protons per succinate.?
only 8 protons per NADH+H+ and 4 protons per succinate. Because of different cytochromes, 2 protons are pump out at the quinone-level.
Proton motive force (pmf)
a transmembrane proton gradient.
- used to drive other energy requiring reactions: flagellum rotation (in bacteria), transport across the membrane, synthesis of ATP.
oxidative phosphorylation
- synthesis of ATP using pmf
- 3 - 4 protons are necessary to phosphorylate 1 ADP to ATP.
What will affect pmf ?
pH and membrane potential will affect proton motive force
products of glycolysis
2 pyruvate 2 ATP (substrate level phophorylation) 2 NADH (oxidative)
products of pyruvate dehydrogenase + TCA
3 CO2 4 NADH (oxidative) 1 FADH2 (oxidative) 1 GTP (substrate level)
total ATP produced?
34-38 ATP per glucose
Cyanide and CO are toxic because ?
no oxygen is brought to the cells, blocks energy transport chain.
If no terminal electron acceptor is available, succinate ? respiration? fermentation?
If no terminal electron acceptor is available,
1) succinate cannot be oxidized by succinate dehydrogenase in the respiratory chain.
2) Glycolysis can still function, because NADH+H+ can be oxidized back to NAD+.
3) If there is terminal electron acceptor, cells will do respiration
Without terminal electron acceptor, cells will then go to fermentation to make ATP.
What is the electron donor and acceptor in fermentation?
an organic compound serves as the electron donor
an organic degradation product serves as the final acceptor of electrons.
net yield of fermentation?
2 ATP per glucose because only glycolysis is functioning
In the absence of O2, the yeast popula0on grows very slowly. Why?
because fermentation yields only a fraction of ATP produced by respiration.
In most anabolic reactions, the source of reducing power is?
NADPH + H+ is used as the source of reducing power.
use NADH for respiration
use NADPH for anabolic reactions
Pentose phosphate pathway require oxygen or not?
Pentose phosphate pathway does NOT require oxygen
The pentose phosphate pathway leads to the generation of a diversity of sugars, for example?
Ribose 5-phosphate may be used to produce ribose and later, deoxyribose
where does Pentose phosphate pathway take place?
In the cytoplasm (Prokaryotes and Eukaryotes).
Anaplerotic pathways
feeds the citric acid cycle with intermediates
e.g. produce malate or oxaloacetate directly from pyruvate
respiratory chain are located in___ in eukaryotes vs.prokaryotes?
In eukaryotes:
- Mitochondria: the enzymes of the TCA cycle, respiration and oxidative phosphorylation
- cytoplasm: the enzymes of glycolysis and fermentation.
In prokaryotes:
the respiratory chain is located in the cytoplasmic membrane, while enzymes of glycolysis, TCA cycle and fermenta0on are located in the cytoplasm.
