Assuming complete combustion of glucose, via glycolysis and the Citric Acid Cycl

Question

Assuming complete combustion of glucose, via glycolysis and the Citric
Acid Cycle, in the presence of oxygen to CO2 and water, yields 2,840
kJ/mol glucose, now answer below two questions:

I. At the end of glycolysis, what fraction of the original chemical
energy in the glucose molecule ends up in pyruvate? (Show the
logic behind your answer)

II. At the end of glycolysis, what fraction of the original chemical
energy in the glucose molecule can be accounted for? (Show the
logic behind your answer)

Explanation / Answer

Respiration is
more complex than glycolysis and is believed to have
evolved much later, after the appearance of cyanobac-
teria. The metabolic activities of cyanobacteria account
for the rise of oxygen levels in the earth’s atmosphere,
a dramatic turning point in evolutionary history.
We consider first the conversion of pyruvate to
acetyl groups, then the entry of those groups into the
citric acid cycle,
also called the
tricarboxylic acid
(TCA) cycle
or the
Krebs cycle
(after its discoverer,
Hans Krebs). We next examine the cycle reactions and
the enzymes that catalyze them. Because intermediates
of the citric acid cycle are also siphoned off as biosyn-
thetic precursors, we go on to consider some ways in
which these intermediates are replenished. The citric
acid cycle is a hub in metabolism, with degradative
pathways leading in and anabolic pathways leading
out, and it is closely regulated
in coordination with other
pathways.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.