Lecture 48 Flashcards Preview

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Flashcards in Lecture 48 Deck (23)
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1
Q

_____ must be synthesized from Uracil in cells undergoing DNA synth/replication.

A

THYMINE

2
Q

Nucleotide _____ phosphate kinase converts Nucleotide ______phosphates to diphosphates, whereas Nucleotide _____phosphate kinases convert the diphosphates to triphosphates.

A

Nucleotide MONOphosphate kinases convert nucleotide MONOphosphates to diphosphates and Nucleotide DIphosphate kinases convert di to tri.

3
Q

Nucleotide monophosphate kinases typically recognize the ____ of nucleotides, whereas diphosphate kinases recognize the _____.

A

Monophosphate kinases typically recognize the BASE, whereas diphosphate kinases recognize the PHOSPHATE.

4
Q

_____ linkage between ribose and the base of nucleosides/tides (tides have phosphates) is between the ____ carbon of ribose and _____ position N in the base.

A

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.

5
Q

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.

A

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.

6
Q

The biosynthesis of Purines begins with synthesis of ______.

A

RIBOSE-5-P

7
Q

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 ____.

A

Conversion of R-5-P to PRPP. This step can be feedback inhibited by IMP, AMP, and GMP.

8
Q

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.

A

Conversion of PRPP to 5-PHOSPHORIBOSYLAMINE via the enzyme Amidophosphoribosyl transferase, using GLUTAMINE (converted to GLUTAMATE) as an amino source.

9
Q

Amidophosphoribosyl transferase is feedback inhibited by ____, ____, and ____ (the monophosphate versions of the particular purines that are made in the reaction.)

A

AMP, IMP, and GMP.

10
Q

The AAs involved in purine biosynth are: 2 _____, one _____, and one Apartate, with 2 C units contributed by _____ (single C unit carrier.)

A

AAs involved in Purine biosynth are: 2 GLUTAMINES, one GLYCINE, and one ASPARTATE, with 2 C units contributed by THF.

11
Q

____ is the nucleotide precursor for both AMP and GMP, with _____ as its base.

A

IMP is the precursor with HYPOXANTHINE as its base.

12
Q

____ acid is added to IMP to form Adenylosuccinate. This process requires _____. Adenylosuccinate loses _____ to form AMP.

A

ASPARTIC Acid is added to IMP to for Adenylosuccinate. This process requires GTP. Adenylosuccinate loses FUMARATE to form AMP.

13
Q

To form GMP, an amino group is transferred from _____ (leaving _____) onto IMP. This process requires ____.

A

An amino group is transferred from GLUTAMINE (leaving GLUTAMATE) onto IMP. This process requires ATP.

14
Q

______ Acid is a drug used to prevent graft rejection. It acts as a ______ uncompetitive inhibitor of IMP dehydrogenase.

A

MYCOPHENOLIC acid is a drug used to prevent graft rejection. It acts as a REVERSIBLE uncompetitive inhibitor of IMP DH.

15
Q

____ acid is the final degradation product for Purines.

A

URIC

16
Q

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.

A

the phosphate can be removed via NUCLEOTIDASES, and the ribose can be removed via PHOSPHORYLASES.

17
Q

Nucleobases can be “salvaged” back to Nucleotidemonophosphates via addition of ______ (which loses a pyrophosphate) by the enzyme ________ transferase.

A

via addition of PRPP (which loses a pyrophosphate) by the enzyme PHOSPHORIBOSYL tarnsferase.

18
Q

Phosphorylase cleaves the _____ bond of Nucleotides while Nucleotidase cleaves the Carbon-____ bond.

A

Phosphorylase cleaves the GLYCOSIDIC bond while Nucleotidase cleaves the Carbon-PHOSPHATE bond.

19
Q

AMP and Adenosine lose ____ in the degradation pathway via ______ enzymes. This is a source of free _____.

A

They lose NH4+ via DEAMINASE enzymes. This is a source of free NH4+.

20
Q

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.

A

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.

21
Q

Allopurinol acts as a ____ inhibitor of _____ oxidase, so less Uric acid is produced from _____. There is also a decrease in _____.

A

It acts as a COMPETITIVE inhibitor of XANTHINE oxidase, so less URIC acid is produced from XANTHINE. There is also a decrease in PRPP.

22
Q

SCID is caused by ____ recessive mutation in Adenine _____, which causes a toxic buildup of ____. As a result, both _____ and _____ cells are reduced.

A

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.

23
Q

____ ___ 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.)

A

Lesh Nyhan syndrom is characterized by an AUTOSOMAL recessive mutation leading to a complete lack of HGPRT.