Glycogenesis Flashcards
The glycogen synthesis occurs by a pathway similar to the reversal of glycogen breakdown
T/F
F
distinctly different from Glycogenesis
Glycogenesis: Activation of Glucose
UDP glucose is formed from _____ and ____ by the enzyme _________
glucose-1-phosphate and UTP
UDPglucose pyrophosphorylase.
Full meaning of UTP is _______
uridine triphosphate
Glycogenesis: Glycogen Synthase
The _____ moiety from UDP-glucose is transferred to a ______ (_____) molecule. The primer is essential to accept the glycosyl unit. The primer is made up of a ____-____ complex.
In the next step,_________ are sequentially added by the enzyme ________
The glucose unit is added to the _______ ((outer or inner?) ) end of the glycogen primer to form an ______ glycosidic linkage and UDP is liberated.
glucose
glycogen primer
glycogenin
protein-carbohydrate
activated glucose units
glycogen synthase
nonreducing ; outer
alpha-1,4
Glycogenin is a ____ protein, having ___ identical monomers.
An oligosaccharide chain of _____ units is added to each monomer.
dimeric
two
7 glucose
Glycogenesis: Branching Enzyme
The glycogen synthase can add glucose units only in ____ linkage.
A branching enzyme is needed to create the ____ linkages.
When the chain is lengthened to ____ glucose residues, the branching enzyme will transfer a block of _____ glucose residues from this chain to another site on the growing molecule.
The enzyme amylo[1,4]→[__]_____ (branching enzyme) forms this alpha-1,6 linkage
To this newly created branch, further glucose units can be added in alpha- ___ linkage by _______
alpha-1,4
alpha-1,6
11 - 12
6 to 8
1,6; transglucosidase
1,4; glycogen synthase.
The phosphorylated form of glycogen phosphorylase is (active or inactive ?)
glycogen synthase becomes (active or inactive?) on phosphorylation.
Active
Inactive
Effect of ATP on
glycogen phosphorylase (liver) glycogen phosphorylase (muscle ) Glycogen synthase (liver) Glycogen synthase (muscle )
Inhibit
Inhibit
Inhibit
Inhibit
Effect of AMP on
glycogen phosphorylase (liver) glycogen phosphorylase (muscle ) Glycogen synthase (liver) Glycogen synthase (muscle )
Activation
Activation
Lol
Lol
Effect of glucose 6 phosphate on
glycogen phosphorylase (liver) glycogen phosphorylase (muscle ) Glycogen synthase (liver) Glycogen synthase (muscle )
Lol
lol
Activate
Activate
Effect of calcium on
glycogen phosphorylase (liver) glycogen phosphorylase (muscle ) Glycogen synthase (liver) Glycogen synthase (muscle )
Activate
Activate
Lol
Lol
von Gierke’s disease
______ enzyme is deficient
Xterized by :
______ ——-glycemia; _____megaly
Glucose-6-phosphatase
Fasting hypo
hepato
Limit dextrinosis aka ____ disease
_____ enzyme is deficient
Xterized by:——— accumulates; _____ ——-glycemia; ____megaly
Cori’s
Debranching enzyme
Highly branched dextrin
Fasting hypo
Hepato
Amylopectinosis aka ______ disease
______ enzyme is deficient
Xterized by: Glycogen with _______ ; ________megaly; ___ ——glycemia; death by age of ___
Anderson’s
Branching
few branches
hepatospleno
mild hypo
5
McArdle’s disease
______ enzyme is deficient
Xterized by :_____ intolerance; accumulation of ______ in muscles
Muscle phosphorylase
Excercise
glycogen
Hers’ disease
_______ enzyme is deficient
Xterized by : _____ ___glycemia; _____megaly; (better or worse?) prognosis than other types
Liver phosphorylase
Mild hypo
hepato
better
The ____ cycle is the first metabolic pathway to be elucidated
urea
The urea cycle is known as _______ urea cycle.
Krebs–Henseleit
Urea cycle
As ——- is the first member of the reaction, it is also called as _____ cycle.
ornithine
Ornithine
The two nitrogen atoms of urea are derived from two different sources, one from _____ and the other directly from the alpha amino group of _______.
ammonia
aspartic acid
Urea cycle
Step 1
One molecule of ______ condenses with ___ in the presence of ___ molecules of ATP to form __________.
The reaction is catalysed by the (mitochondrial or cytoplasmic?) enzyme ________________.
ammonia
CO2
two
carbamoyl phosphate
Mitochondrial
carbamoyl phosphate synthetase-I (CPS-I)
_____ reaction is the rate-limiting step in urea formation. It is irreversible and allosterically regulated.
CPS-I
Urea cycle : Formation of Citrulline
The second reaction is (mitochondrial or cytoplasmic?) .
The _____ group is transferred to the NH2 group of _____ by _______________
Mitochondrial
carbamoyl
ornithine
ornithine transcarbamoylase (OTC)
In urea cycle
The citrulline leaves the ____ and further reactions are taking place in ______.
mitochondria
cytoplasm
Citruline is present or absent in
tissue proteins
milk
blood.
Absent
Present
Absent
Urea cycle: Formation of Argininosuccinate
One molecule of ______ adds to citrulline forming a ____-______ bond which provides the 2nd nitrogen atom of urea. __________ catalyses the reaction
This needs hydrolysis of ___ to ____ level, so two high energy phosphate bonds are utilized.
aspartic acid
carbon to nitrogen
Argininosuccinate synthetase
ATP to AMP
The PPi is an (activator or inhibitor?) of Formation of Argininosuccinate
In urea cycle
Inhibitor
Urea cycle : Formation of Arginine
Argininosuccinate is cleaved by _______ to _____ and _____.
The enzyme is inhibited by _____. But this is avoided by the ______ of the enzyme.
The fumarate formed may be funnelled into TCA cycle to be converted to ____ and then to _____ to be transaminated to _____
argininosuccinate lyase
arginine and fumarate
fumarate
cytoplasmic localization
malate; oxaloacetate; aspartate
Thus the urea cycle is linked to TCA cycle through _______.
The 3rd and 4th steps taken together may be summarized as: Citrulline + aspartate → ________ +______
fumarate
Arginine ; fumarate
Urea cycle: Formation of Urea
The final reaction of the cycle is the _____ of _____ to urea and ____ by ______
hydrolysis of arginine
ornithine
arginase
The ornithine from urea cycle returns to the _____ to react with another molecule of _____ so that the cycle will proceed.
Thus, ornithine may be considered as a catalyst which enters the reaction and is regenerated.
mitochondria
carbamoyl phosphate
The urea cycle consumes ___ high energy phosphate bonds
4
The urea cycle and TCA cycle are interlinked, and so, it is called as “____________”.
urea bicycle
