ATP Flashcards
Anabolism
synthetic reactions
genesis
glycogenesis
Catabolism
breakdown reactions
lysis
glycolysis
Why is metabolism important?
Energy is required for:
- motion
- transport
- biosynthesis
- thermoregulation
Cells requires sources of free energy
maintaining life requires constant investment in energy, when a cell can no longer obtain energy it dies and decays
- free energy is energy available to perform work and is
accquired from nutrient molecules
C6H12O6+6)2->6CO2+6H2O+ energy
Enthalpy (H)
the heat content of the reacting system
Entropy (s)
the randomness or disorder in a system
Gibbs Free Energy
energy capable of doing work at a constant temp and pressure
In cells the enthalpy change (deltaH) reflects
- the chemical bonds broken and formed
- delta H is positive when energy is absorbed by the
reaction (endothermic)
In cells the change in entropy (delta S) describes
the formation of large complex proteins from smaller molecules or vice verse
- delta S is positive when randomness increases
(breaking a bigger molecule into smaller molecule)
Gibbs free energy equation
For a reaction to occur spontaneous delta G must be
negative (energy is released by the reaction)
Catabolism is endergonic or exergonic
exergonic
products have less free energy and so are more stable than the reactants
exergonic reactions
endergonic reactions
Coupling of reactions:
an endergonic reaction can be driven in the forward direction by coupling it to an exergonic reaction
the hydrolysis of ATP provides the energy to drive an unfavourable reaction
ATP is the energy currency of the cell
achieved by phosphate group transfer
Substrate level phosphorylation
- formation of ATP by the transfer of a phophoryl froup
from a substrate to ADP - distinguished from respiration linked phosphorlyation
- substrate level phosphorylation requires soluble
enzymes and chemical intermediates - respiration linked phosphorylates involve membrane
bound enzymes and transmembrane gradients of
protons and require oxygen
Enzymes influence the delta G of the reaction.
True or False?
False
DOES NOT INFLUENCE DELTA G
cofactors and coenzymes
prosthetic groups
- non-protein cofactor that is covalently bound to the
enzyme - not released as part of the reaction
- acts as a temporary store for e—– or reaction
intermediates
What vitamin is a precursor for FAD/FMN coenzyme?
B2 (riboflavin)
What vitamin is a precursor for NAD+?
Niacin
Nicotinamide Adenine Dinucleotide (NAD+):
NAD+ and NADP+ accept PAIRS of e- to form NADH or NADPH
it is the nicotinamide that is the functional part of the molecule
NADH for
NADPH for
- ATP synthesis
- reductive biosyntheses
Recycling of NADH and FADH2 is via the
respiratory chain in the mitochondria
OXIDATIVE PHOSPHORYLATION
summary of energy metabolism
glycolysis summary
2 fates of pyruvate
- aerobic: oxidation and complete degradation
- hypoxic: reduced to lactate
structure of mitochondria
Transport of pryuvate into the mitochondria:
- aerobic: pyruvate transport occurs via the specific
carrier protein embedded in the mitochondrial
membrane - pyruvate undergoes oxidative deccarboxylation by the
***pryuvate dehydrogenase complex to form acetyl
CoA - reaction is irreversible and is the direct physical link link between
glycolysis and the citric acid cycle
Reaction equation the is the link between glycolysis and the citric acid cycle?
pyruvate +CoA + NAD+ -> acetyl CoA + CO2 + NADH + H+
Glycolysis priming stages
Glucose-G3P is training stage because energy needs to be put in; ENERGY REQUIRED!!!
Committed step is F6P to FBP; by phosphofructoskinase-1; want more G3P
Glycolysis payoff stages
GAPDH changes G3P to 1,3 BGP by reducing 1 NAD to NADH
**PGK uses substrate level phosphorylation to change 1,3 BGP to 3-phosphoglycerate
Mutase changes 3-phosphoglycerate into 2-phospho-glycerate
Enolase changes this into phosphophenolpyruvate
***Which is turned into pyruvate by PRYUVATE KINASE; also substrate level phosphorylation
Fate of pyruvate:
Why has this system of lactate production evolved?
RBC do not have mitochondria so no Kreb cycle so always make lactacte, which is taken to liver
A hydride ion
Is a proton with two electrons
Kerbs/Citric acid cycle
Kerbs/Citric acid cycle: 2 carbon acetyl groups are fed into the cycle which
Enzymatically oxidises them to CO2; the energy released is stored as either ATP, NADH, FADH2
What are the 9 steps of the critic acid cycle?
1) oxaloacetate joins Acetyl CoA to form citrate
2) citrate is converted to isocitrate
3) isocitrate id decarboxylated to alpha ketoglutarate (NADH produced)
4) succinate CoA is added to alpha ketoglutarate by oxidative decarboxylation (NADH produced)
5) succinyl CoA converted to succinate (ATP)
6) succinate is dehydrogenated to fumarate (FADH2)
7) fumurate hydrated to malate
8) malate dehydrogenated to oxoaloacetate (NADH)
9) Citric acid cycle begins again
Step 1 of the citric acid cycle:
- acetyl CoA and oxaloacetate joined by enzyme citric synthesis in a condensation reaction to form citrate
Step 2 of the citric acid cycle
Aconitase enzyme converts citrate into isocitrate
Step 3 of the citric acid cycle
Enzyme isocitrate dehydrogenase -> Isocitrate is decarboxylated to alpha ketoglutarate using NAD and creating NADH
Step 4 of the citric acid cycle:
Alpha-ketoglutarate dehydrogenase -> alpha ketoglutarate and succinate CoA join to form succinyl CoA, CO2 and uses NAD and forms NADH
Step 5 of the citric acid cycle
Enzyme succinyl-CoA synthetase converts succinate to succinyl CoA via substrate level phosphorylation producing ATP
Step 6 of the citric acid cycle:
Enzyme Succinate dehydrogenase -> Succinate is dehydrogenated to fumurate generating FADH2
Step 7 of the citric acid cycle
Enzyme fumurase hydrates fumurate to malate
Step 8 of the citric acid cycle
Enzyme Malate dehydrogenase -> Malate is dehydrogenated to oxaloacetate generating NADH
THE CITRIC ACID CYCLE PRODUCT TALLY:
1 turn of cycle: 2 carbons enter (acetyl CoA), 2 carbons leave (CO2 x2)
For one glucose molecule:
Glycolysis: 4 ATP, NADH
Citric acid cycle:
- 3 x NADH x2 = 6NADH
- 1x ATP x2 = 2 ATP
- 1 x FADH2 x 2 = 2 FADH2
Regulation of the citric acid cycle
- flow of carbon atoms from pyruvate into and through the citric acid cycle is tightly regulated at 2 levels:
1) conversion of pyruvate into acetyl Co-A (PDH reaction)
2) entry of acetyl-CoA into the TCA cycle (citrate synthase reaction)
3) isocitrate dehydrogenase to alpha ketoglutarate dehydrogenase reaction
Regulation of the TCA cycle
The electron transport chain
- NADH and FADH2 are re-oxidised using electron transport proteins
- series of coupled oxidation and reduction reactions
- electron transport chain or respiratory chain
- terminal acceptor of electrons is O2 which is REDUCED to H20
ATP synthesis via oxidative phosphorylation utilises ——- energy and ——— ——- energy caused by a difference in the ———— provided by ——- pumping from the ——- to the ———- ——- by complexes —-, ——-, ——.
The ——- motive force (the separation of charge between the ———— and the ———— ———) drives the synthesis of ATP using the enzyme ——— ————-
- electrical
- chemical potential
- proton concentration
- proton pumping
- mitochondrial matrix
- inter membrane space
- 1
- 3
- 5
- proton motive force
- intermembrane space
- mitochondrial matrix
- ATP synthase
ATP synthase
- composed to structures F0 and F1
- F0 resides in the innner membrane of mitochondria
- F1 projects into the matrix
- as H+ flows through the membrane, the cylinder within F0 and the y shaft rotate
- as the y shaft interacts with each of the beta subunits of F1, they change conformation and facilitate the formation of ATP from ADP and Pi