life processes nucleotides are the activated precursors of nucleic acids As such they are necessary for the replication of the genome an adenine nucleotide ATP is the universal currency of energy A guanine ID: 933804
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Slide1
Nucleotide Biosynthesis
Slide2nucleotides is essential for life
processes
nucleotides
are the
activated precursors
of nucleic
acids. As such, they are necessary for the replication of the genome
an
adenine nucleotide, ATP, is
the universal currency of energy. A guanine
nucleotide,
GTP
, also serves as an energy source for a more select group of biological processes.
Third
, nucleotide derivatives
such as
UDP-glucose
participate in biosynthetic processes such as the formation of glycogen.
nucleotides are essential
components of signal-transduction pathways.
cyclic
AMP and cyclic GMP
are
second
messengers that transmit signals both within
and
between
cells
.
Slide3RNA & DNA
Slide4RNA & DNA
Slide5Slide6Purines and Pyrimidines
Adenine
Guanine
Thymine/Uracil
Cytosine
Two
Purines
Two
Pyrimidines
Slide7Synthesis Pathways
For both purines and pyrimidines there are two means of synthesis (often regulate one another)
de novo (from bits and parts)
salvage (recycle from pre-existing nucleotides)
Salvage Pathway
de novo Pathway
Slide8Many Steps Require an Activated Ribose Sugar (PRPP)
5’
Slide9de novo Synthesis
Committed step: This is the point of no return
Occurs early in the biosynthetic pathway
Often regulated by final product (feedback inhibition)
X
Slide10Biosynthesis of
Pyrimidines
Pyrimidine rings are synthesized independent of the ribose and transferred to the PRPP (ribose)
Generated as UMP (uridine 5’-monophosphate)
Synthesized from:
Glutamine
CO
2
Aspartic acid
Requires ATP
Uracil
Cytosine
Slide11DENOVO Synthesis of Pyrimidine
Slide12DENOVO Synthesis of Pyrimidine
1.
Bicarbonate and Other Oxygenated Carbon Compounds Are Activated by
Phosphorylation
2.
Orotate
Acquires a Ribose Ring from PRPP to Form a
Pyrimidine
Nucleotideand
Is Converted into
Uridylate
Slide13DENOVO Synthesis of Pyrimidine
3. CTP is Formed by Amination of UTP
Slide14DENOVO Synthesis of Pyrimidine
Slide15Slide16Purine
Biosynthesis (de novo)
Atoms derived from:
Aspartic acid
Glycine
Glutamine
CO
2
Tetrahydrofolate
Also requires
4 ATP’s
Purines are synthesized on the Ribose ring
Committed Step
Inhibited by
AMP, GMP, IMP
X
Slide17DENOVO Synthesis of
P
u
rine
Slide18DENOVO Synthesis of Pu
rine
Slide19DENOVO Synthesis of Pu
rine
Slide20Salvage Pathway for Purines
Hypoxanthine
or
Guanine
+
PRPP
= IMP or GMP + PPi
Hypoxanthineguanosylphosphoribosyl transferase
(HGPRTase)
Adenine
+
PRPP
= AMP + PPi
Adeninephosphoribosyl transferase
(APRTase)
Slide21Biosynthesis: Purine vs Pyrimidine
Synthesized on PRPP
Regulated by GTP/ATP
Generates IMP
Requires Energy
Synthesized then added to PRPP
Regulated by UTP
Generates UMP/CMP
Requires Energy
Purine
Pyrimidine
Both are very complicated multi-step process which
your kindly professor does not expect you to know in detail
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