Download Nuclear Chemistry

8th Set of Notes
Examples:
See some examples of how knowledge of G and K is important in biochemistry and
in acid-base chemistry
Change in the Ka with temp.
Calculation of the activities and concentrations of various ionized species in solution.
Thermodynamics of metabolites
Glycolysis - glucose is converted into pyruvate producing adenosine triphosphate (ATP)
Next in aerobic systems, pyruvate enters the
In less aerobic
or in anaerobic in yeast,
The overall combustion of glucose is very spontaneous (large negative ______________)
Also Ho is large and negative, leading to the case
So if burned directly, then nearly all chemical potential is _____________ as _________.
But in a living cell some of the chemical potential is retained as _____________
_________ ______________ in the form of ATP and other ____________________
_____________________.
First step in metabolism of glucose is the formation of glucose-6-phosphate, but this is
not spontaneous:

Go’ = ___________
In glycolysis, the reaction is coupled to the hydrolysis of ATP to form Adenosine
diphosphate. This is thermodynamically favorable


Go’ = ________________
Thus the overall process of formation of glucose-6-phosphate which includes the
hydrolysis of the ATP is:
and it’s G0’ is:
Reactions are enzyme catalyzed. (Hexokinase) Does this affect the thermodynamics?
2nd step if isomerization of glucose-6-phosphate to furctose-6-phosphate catalyzed by
phosphoglucose isomerase.
Go’ is ______________, so this step is ( ___________ ___________________)
The equil constant at 25oC is ___________ and thus __________________
product is formed.
The third step is attachment of a second phosphate group to fructose-6-phosphate to
form fructose-1,6-diphosphate. This step is driven also by phosphate transfer from ATP
and its Go’ is ________________.
The fourth step is the six-carbon sugar fructose-1,6-diphosphate is split into two threecarbon compounds, dihydroxyacetone phosphate and glyceraldehyde-3-phosphae,
catalyzed by the enzyme aldolase.
This rxn. has a Go’ of +23.8. which would make it very ________________ under std
conditions, but the metabolites in the cell are significantly more dilute than 1M giving a
reaction quotient Q of 0.0001. This means that the actual G is
and at higher temp., the G is also less positive, giving G of about __________.
The fifth step involves oxidation and phosphorylation of glyceraldehyde-3-phosphate
to 1,3-diphosphoglycerate with nicotinamide adenine dinucleotide (NAD), a biological
oxidant and the phosphate is from an inorganic pool of phosphate, Pi
Go’298 = _____________ and so is
But the next step, the sixth step, helps to keep this going. Here one of the phosphates of
1,3-diphosphoglycerate is transferred to ADP to generate ATP and 3-phosphoglycerate.
The reaction:
has a Go’298 of ________________
The seventh step is an isomerization reaction and the eighth step is also an
isomerization.
The ninth step is the final step and involves taking the remaining phosphate and
transferring it to ADP to form ATP.
OVERALL
and Go’298 is equal to the sum of _________ ________ ________ _________
_________ and is equal to: _____________
There is a net formation of _______ mol of ATP and _______ mol of physiological
reductant NADH per mole of ______________ consumed.
So here energy a good amount of the chemical potential is retained as chemical energy
for use in other biosynthetic or energy requiring reactions.
Examples of the use of this “stored energy”
Strenuous exercise causes pyruvate to change to lactate. And NADH helps out in this
rxn!
pyruvate + NADH + H+ -> lactate +
Biological Redox Reactions
Oxidation-reduction reactions are an essential type of reaction in energy storage and
conversion for biological organisms
Examples include:
Pyruvate produced from glycolysis undergoes oxidative decarboxylation for form acetyl
coenzyme A, which then enters the citric acid cycle.. In the citric acid cycle, the
acetate is transferred to oxaloacetate to form the six carbon molecule, citrate. Citrate
undergoes a series of a minimum of ______ reactions involving progressive oxidation of
two of the carbon atoms to CO2 and return the remaining four-carbon portion as
oxaloacetate for reentry into the cycle. Coupled to the oxidation of the acetate to CO2 is
the reduction of 3 moles of ___________ to NADH and the production of 1 mol of
reduced flavin adenine dinulceotide FADH2 This reducing power generated in the citric
acid cycle is used for biosynthetic reactions and for the formation of ATP by oxidative
respiration in mitochondria. The completing step in the citric acid cycle is the oxidation
of malate to oxaloacetate coupled with the reduction of NAD+ to NADH by the enzyme
malate dehydrogenase
The Go’ for this (from o’ values) is:
This step in the cycle is __________ ________________ under normal std. conditions,
but under condition where the demand for NADH is high, that is when [NADH]/[NAD]
is low. Under these conditions, the conversion will happen.
Example of METABOLIC REGULATION
Other examples of Biological Redox Reactions
NADH-Q Reductase
Cytochrome Reductase
Cytochrome c Oxidase
Double Strand Formation in Nucleic Acids
Effect of Ions on Proteins and Nucleic Acid Interactions