Transcript Q26to35

Questions 26 - 35
Glucose Disposal – The Pathways
26. Parts of Glucose Disposal
•
Which process requires ATP?
A. Addition of glucose from UDP-glucose to a growing glycogen
chain
once the glucose is activated, no more ATP needed
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B. Conversion of glucose residues in glycogen to glucose 6phosphate
phosphorolysis, uses just phosphate
C. ANY of the reactions in the fatty acyl synthase complex (ie,
from malonlyl-CoA to fatty acyl-CoA)
energy was invested in making malonyl-CoA
D. Carboxylation of acetyl-CoA to give malonyl-CoA
E. Decarboxylation of pyruvate to acetyl-CoA
very catabolic,
yes
27. Choice of G6P fates
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Which statement about the balance between
glycogenesis and glycolysis in muscle after a
carbohydrate meal is CORRECT?
A. Consumption of ATP in glycogenesis stimulates glycolysis
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Yes, PFK responds to lowering of ATP
B. Insulin stimulates dephosphorylation of phosphofructokinase
PFK not regulated by reversible phosphorylation
C. Glucose 6-phosphate concentration rises about 100-fold and
stimulates glycogen synthase
G6P never gets that high in muscle – it inhibits HK
D. Production of ATP in glycolysis is the major driving force for
glycogenesis
demand drives oxidation, not vice versa
E. A rise in the level of ATP stimulates glycogen synthase
tempting, but ATP already high and extra glycolysis not likely to make it higher
28. Glucokinase vs Hexokinase
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Which statement describes a genuine feature
of glucokinase which is NOT shared by
hexokinase?
A. Glucokinase irreversibly produces glucose 6-phosphate from
glucose both GK and HK make G6P from glucose – both ‘irreversible’c
B. Glucokinase is inhibited by a build up of glucose 6-phosphate
only HK is inhibited by G6P
C. Glucokinase is stimulated by phosphorylation
neither GK nor HK are regulted by reversible phosphorylation
D. Glucokinase can work on any hexoses
only HK can work on any hexose
E. Glucokinase is not saturated by 10 mM glucose
HK is saturated by 1 mM glucose, GK is not even saturated by 10 mM glucose
29. Glycogen Synthesis
•
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Which statement about the synthesis of
glycogen from glucose is INCORRECT?
A. The formation of UDP-glucose is facilitated by the joining of two
phosphates to form pyrophosphate
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sneaky! pyrophosphate is involve but it is hydrolysed
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B. In UDP-glucose, the glucose residue is joined to UDP at the C1 end of glucose.
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the C1 is the “activated” end
C. Glycogen synthesis occurs in the cytoplasm
most certainly
D. Activated glucose residues on UDP-glucose form glycosidic
bonds with the C-4 ends of the growing glycogen chain
same as B
E. UTP is regenerated by the reaction of UDP and ATP
yes. forgot to mention that this year!
30. Glycogen Synthesis
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Which statement is CORRECT?
A. A rise in intracellular glucose concentration is
sufficient to increase the rate of glycogenesis in liver
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it is. Stimulates dephosphorylation of GS
B. Liver does not have branching enzyme
it does. Liver glycogen and muscle glycogen are the same
C. The size of a glycogen molecule is unlimited in liver
perhaps less restricted than muscle but not unlimited
D. Glucose transport into liver requires insulin
perhaps less restricted than muscle but not unlimited
E. Liver glycogenesis can occur without a concomitant
increase in a catabolic pathway
all anabolic pathways must have a catabolic consequence!
31. Fructose metabolism
•
Which statement is CORRECT?
A. Only the liver can dispose of fructose
muscle can too
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B. Fructose is trapped as fructose 6-phosphate in the liver
no, as fructose 1-phosphate
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C. A fructokinase deficiency would severely deplete ATP levels in
liver after a meal containing fructose
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would just stop trapping and the consumption of ATP
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D. The liver cannot convert fructose into glucose
F1P to triose phosphates, back up gluconeogenesis
E. The aldolase involved in liver fructose metabolism is slow in
comparison to the rate of fructose trapping
this is what causes the ATP depletion
32. Insulin Action - WAT
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In white adipose tissue, which process is
NOT stimulated by insulin?
A. The rate of glucose uptake
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GLUT-4 stimulated
B. Pyruvate dehydrogenase activity
PDH phosphatase activated
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C. Acetyl-CoA carboxylase activity
the main drive!
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D. Expression of fatty acyl synthase
E. Lipolysis
inhibited by insulin
it is (put down by high fat)
33. Lipogenesis – AcCoA transport
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Hydroxycitrate is an inhibitor of ATP-citrate lyase. What
would be the MOST LIKELY consequence of adding
hydroxycitrate to cells undergoing lipogenesis?
A. The movement of acetyl-CoA into the cytoplasm would
decrease
ACL aids movement of acetyl CoA to cytoplasm
B. Production of ATP would stop
ACL not energy generating
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C. Mitochondrial acetyl-CoA levels would rapidly deplete
acCoA would stay in mito
D. The rate of fatty acid production would increase
inhibitor of lipogenesis
E. Cytoplasmic acetyl-CoA levels would increase.
stopping movement out will decrease cytosolic acCoA
34. Pentose Phosphate Pathway
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Which statement best describes the
relationship between the pentose phosphate
pathway (PPP) and lipogenesis?
A. The PPP produces the glycerol needed for esterification of
newly formed fatty acids
it doesn’t produce glycerol
B. Lipogenesis provides glycerol 3-phosphate for the PPP
a nonsense statement
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C. Lipogenesis uses NADPH produced by the PPP
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D. The PPP provides ATP to fuel lipogenesis
true!
no ATP made by PPP
E. The PPP is necessary to provide the carbon dioxide needed to
produce malonyl-CoA
carbon dioxide not in short supply
35. Fatty Acyl Synthase
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Which statement regarding Fatty Acyl Synthase
(FAS) is CORRECT?
A. FAS is inhibited by insulin
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FAS expression stimulated by insulin
B. The order of reaction in FAS is (in sequence) oxidation,
dehydration, and oxidation
involves reduction
C. FAS decides if a fatty acid is to be desaturated during
lipogenesis. Once a saturated fatty acid has been made, it
cannot be unsaturated.
FAs can be unsaturated at C9 or less
D. FAS incorporates carbon dioxide into the growing fatty acid
chain
the CO2 that makes malonyl-CoA is lost in FAS
E. During the elongation step, the two new carbon atoms are
added to the carboxy- end of the growing fatty acid
reactive unit is the acetyl – growing chain moves to this