Lecture 48 Flashcards
_____ must be synthesized from Uracil in cells undergoing DNA synth/replication.
THYMINE
Nucleotide _____ phosphate kinase converts Nucleotide ______phosphates to diphosphates, whereas Nucleotide _____phosphate kinases convert the diphosphates to triphosphates.
Nucleotide MONOphosphate kinases convert nucleotide MONOphosphates to diphosphates and Nucleotide DIphosphate kinases convert di to tri.
Nucleotide monophosphate kinases typically recognize the ____ of nucleotides, whereas diphosphate kinases recognize the _____.
Monophosphate kinases typically recognize the BASE, whereas diphosphate kinases recognize the PHOSPHATE.
_____ linkage between ribose and the base of nucleosides/tides (tides have phosphates) is between the ____ carbon of ribose and _____ position N in the base.
GLYCOSIDIC linkage between ribose and base of nucleosides/tides is between the 1 carbon of the ribose and the 9 position N of the base.
The ribose component of nucleosides/tides comes from the ____ ____ ____ (PPP.) ____-6-P is converted to 6-phosphogluconolactone via the enzyme ____-6-P _____ (which requires _____ as a cofactor), and in two more steps the ribose-5-P is formed.
From the PENTOSE PHOSPHATE PATHWAY. G-6-P is converted to 6-Phosphogluconolactone via the enzyme G-6-P DEHYDROGENASE (which requires NADP as a cofactor), and in two more steps the ribose-5-P is formed.
The biosynthesis of Purines begins with synthesis of ______.
RIBOSE-5-P
One of the rate limiting steps in purine synthesis involves the conversion of R-5-P to ______ via the enzyme Ribose Phosphate pyrophospho-kinase and ATP. This step can be feedback inhibited by ___, ___, and ____.
Conversion of R-5-P to PRPP. This step can be feedback inhibited by IMP, AMP, and GMP.
The major regulatory step in Purine biosynth involves the conversion of PRPP to 5-_________ via the enzyme Amidophosphoribosyl transferase, using ______ (converted to ______ )as an amino source.
Conversion of PRPP to 5-PHOSPHORIBOSYLAMINE via the enzyme Amidophosphoribosyl transferase, using GLUTAMINE (converted to GLUTAMATE) as an amino source.
Amidophosphoribosyl transferase is feedback inhibited by ____, ____, and ____ (the monophosphate versions of the particular purines that are made in the reaction.)
AMP, IMP, and GMP.
The AAs involved in purine biosynth are: 2 _____, one _____, and one Apartate, with 2 C units contributed by _____ (single C unit carrier.)
AAs involved in Purine biosynth are: 2 GLUTAMINES, one GLYCINE, and one ASPARTATE, with 2 C units contributed by THF.
____ is the nucleotide precursor for both AMP and GMP, with _____ as its base.
IMP is the precursor with HYPOXANTHINE as its base.
____ acid is added to IMP to form Adenylosuccinate. This process requires _____. Adenylosuccinate loses _____ to form AMP.
ASPARTIC Acid is added to IMP to for Adenylosuccinate. This process requires GTP. Adenylosuccinate loses FUMARATE to form AMP.
To form GMP, an amino group is transferred from _____ (leaving _____) onto IMP. This process requires ____.
An amino group is transferred from GLUTAMINE (leaving GLUTAMATE) onto IMP. This process requires ATP.
______ Acid is a drug used to prevent graft rejection. It acts as a ______ uncompetitive inhibitor of IMP dehydrogenase.
MYCOPHENOLIC acid is a drug used to prevent graft rejection. It acts as a REVERSIBLE uncompetitive inhibitor of IMP DH.
____ acid is the final degradation product for Purines.
URIC
The phosphate of Nucleotide monophosphates can be removed via the enzyme ______, and the ribose can be removed via the enzyme ______, reducing the nucleoside monophosphates to _____bases and finally uric acid.
the phosphate can be removed via NUCLEOTIDASES, and the ribose can be removed via PHOSPHORYLASES.
Nucleobases can be “salvaged” back to Nucleotidemonophosphates via addition of ______ (which loses a pyrophosphate) by the enzyme ________ transferase.
via addition of PRPP (which loses a pyrophosphate) by the enzyme PHOSPHORIBOSYL tarnsferase.
Phosphorylase cleaves the _____ bond of Nucleotides while Nucleotidase cleaves the Carbon-____ bond.
Phosphorylase cleaves the GLYCOSIDIC bond while Nucleotidase cleaves the Carbon-PHOSPHATE bond.
AMP and Adenosine lose ____ in the degradation pathway via ______ enzymes. This is a source of free _____.
They lose NH4+ via DEAMINASE enzymes. This is a source of free NH4+.
Gout is caused by defects in the _____ pathway, speifically in ____ synthase and HGPRT, that causes _____, and eventually Uric acid, to build up. This leads to a net increase in the _____ and _____ pathways.
Caused by defects in the SALVAGE pathway, specifically in PRPP synthase and HGPRT,
causing PRPP, and eventually uric acid, to build up. This leads to a net increase in the BIOSYNTHETIC and DEGRADATION pathways.
Allopurinol acts as a ____ inhibitor of _____ oxidase, so less Uric acid is produced from _____. There is also a decrease in _____.
It acts as a COMPETITIVE inhibitor of XANTHINE oxidase, so less URIC acid is produced from XANTHINE. There is also a decrease in PRPP.
SCID is caused by ____ recessive mutation in Adenine _____, which causes a toxic buildup of ____. As a result, both _____ and _____ cells are reduced.
It is caused by an AUTOSOMAL recessive mutation in Adenine DEAMINASE (ADA), which causes a toxic buildup of dAMP. As a result, both T and B cells are reduced.
____ ___ syndrome is characterized by a(n) ______ recessive mutation leading to a complete lack of _____. These patients tend to self-inflict harm (i.e. biting lips.)
Lesh Nyhan syndrom is characterized by an AUTOSOMAL recessive mutation leading to a complete lack of HGPRT.
