For every pyrimidine mononucleotide synthesized de novo, 5 ATPs
are consumed. For every purine nucleotide synthesized de novo, 9
ATPs are consumed. Because of this high cost, it is essential to
tightly control nucleotide synthesis to closely match the needs of
the cell at any given time. When the energy charge of a cell is
low, cells will not replicate DNA. There is no need for
deoxyribonucleotides (dNTPs) so their synthesis is turned off.
Conversely, when the energy charge is...
Why is de novo pyrimidine nucleotide synthesis regulated at the
aspartate transcarbamoylase step in bacteria and at the carbamoyl
phosphate synthetase step in eukaryotes? B) Why isn’t the formation
of 5-phosphoribosyl-1-pyrophosphate (PRPP) the regulated step in
the de novo synthesis of purine nucleotides?
Draw a color-coded diagram (to indicate the origin of each atom)
for the de novo biosynthetic pathway of purine nucleotides
AMP and GMP. You must provide structures and names of all the
intermediates, cofactors involved, names of enzymes, and other
necessary information for full credit
What is your best estimate of the rate of de novo somatic
mutations? On what studies do you base your estimate? Explain the
method(s) used in those studies and the assumptions on which the
numbers are based.
How is the reciprocal use of nucleotides useful in purine
synthesis?
Which vitamin supplement is taken during the first trimester of
pregnancy to prevent the birth defect known as spina bifida?
How is a chloroplast similar to a mitochondria in regard to
energy production?
Why are reactions of the Calvin cycle called the “dark
reactions”?
Purines synthesis
begins with a purine skeleton that will be attached to ribose
5-phosphate once it's complete.
results in the production of deoxyribonucleotides first.
is completed without folic acid.
begins with ribose 5-phosphate.