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Biochemistry - Block 2 > Gluconeogenesis and Carb Storage > Flashcards

Gluconeogenesis and Carb Storage Flashcards

1
Q

Gluconeogenesis require how much more energy than glycolysis requires?

A

3x

  • 4 ATP
  • 2 NADH
  • 2 GTP
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2
Q

What kind of cells in the body rely on glycolysis?

A

RBC
Brain and CNS
Muscle

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3
Q

Location of Glycolysis

A

Cytosol only

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4
Q

Gluconeogenesis location

A

the Liver and Kidney mitochondria, cytosol, ER lumen

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5
Q

First step of Gluconeogenesis and it’s location

A

G-6-P is converted into Glucose via Glucose 6- phosphatase ( this enzyme is ONLY found in the liver)
location of this step : luminal side of ER

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6
Q

Lack of insulin disease

A

type 1 diabetes

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7
Q

insufficient insulin/ insulin resistance

A

type 2 diabetes

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8
Q

Type 1 and 2 causes gluconeogenesis pathway to be? and this causes

A

uninhibited, the liver pumps out glucose contributing to the already high blood glucose

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9
Q

the liver pumps out glucose into?

A

blood stream

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10
Q

A drug used to treat type 2 diabetes?

A

Metformin

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11
Q

How does metformin work?

A

stimulates AMPK

which results in insulin INDEPENDENT inhibition of gluconeogenesis

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12
Q 
Insulin levels in relation to states of 
Fed
Fasted
Stress
Effect on break down of glycogen
A

Fed : Increase levels of insulin
Fasted : Low levels of insulin
Stress : no effect
Insulin would INHIBIT breakdown of glycogen

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13
Q 
Glucagon levels in relation to states of 
Fed
Fasted
Stress
Effect on break down of glycogen
A

Fed : low
Fasted : high
Stress : no effect
Glucagon would promote breakdown of glycogen

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14
Q 
Corticosteroids levels in relation to states of
Fed
Fasted
Stress
Effect on break down of glycogen
A

Fed: no effect
Fasted: Increase levels
stress : Increase levels
Promote glycogen break down

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15
Q 
Adrenaline levels in relation to states of
Fed
Fasted
Stress
Effect on break down of glycogen
A

Fed: No effect
Fasted: No effect
Stress : Increase
Effect of hormone: promote glycogen breakdown

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16
Q

Liver contains glucose 6-phosphatase.
Muscle does not have this enzyme.
WHY?

A

The liver releases glucose to the blood to be taken up by brain and active muscle. The liver regulates blood glucose levels (gluconeogenesis).
The muscle retains glucose 6-phosphate to be use for energy (glycolysis). Phosphorylated glucose is not transported out of muscle cells (no gluconeogenesis).

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17
Q

Gluconeogenesis is needed to maintain blood glucose levels under ____ conditions.

A

fasting conditions.

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18
Q

Precursors of gluconeogenesis are

A

lactate, glycerol, and several amino acids, but never acetyl-CoA.

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19
Q

Gluconeogenesis requires

A

ATP, GTP, and NADH.

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20
Q

This ORGAN is the primary gluconeogenic tissue; the pathway requires participation of enzymes located in the ?

A

organ: Liver

mitochondria, cytosol, and endoplasmic reticulum of the liver.

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21
Q

The unique reactions of gluconeogenesis are catalyzed by :

A

pyruvate carboxylase, phosphoenolpyruvate carboxykinase (PEPCK), fructose 1,6-bisphosphatase, and glucose 6-phosphatase.

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22
Q

The rate-limiting reaction in gluconeogenesis is catalyzed by fructose 1,6-bisphoshatase which is ______ by fructose 2,6-bisphosphate (F2,6BP) and stimulated by glucagon. Note, reciprocally, F2,6BP ______phosphofructokinase in glycolysis.

A

The rate-limiting reaction in gluconeogenesis is catalyzed by fructose 1,6-bisphoshatase which is inhibited by fructose 2,6-bisphosphate (F2,6BP) and stimulated by glucagon. Note, reciprocally, F2,6BP stimulates phosphofructokinase in glycolysis.

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23
Q

_____ is the most common disease related to gluconeogenesis dysfunction, due to the importance of gluconeogenesis in maintaining blood glucose homeostasis

A

Diabetes is the most common disease related to gluconeogenesis dysfunction, due to the importance of gluconeogenesis in maintaining blood glucose homeostasis

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24
Q

Hence the average person with type-2 diabetes has a __times higher rate of gluconeogenesis. The drug ____ can treat type-2 diabetes by inhibiting gluconeogenesis.

A

Three times, Metformin

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25
Q

Type 1 Diabetes

A

lack of insulin; results from the body’s failure to produce enough insulin. Also known as insulin

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26
Q

Type 2 Diabetes

A

insulin resistance; cells fail to respond properly to insulin. Increased rate of gluconeogenesis results in increased blood glucose levels.

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27
Q

The synthesis and breakdown of glycogen is regulated to maintain blood glucose levels. Which organ is this important for?

28
Q

In ___ - The synthesis and breakdown of glycogen is regulated to meet the energy requirements of the muscle cell.

29
Q

Glycogen builds during what time of day?

A

After dinner in preperation for the night while fasting

30
Q

Glycogen is stored in ?

A

Glycogen Granulues of
Muscle
Adipose
Liver

31
Q

Branched structure

A

1,6 glycosidic linkage

32
Q

adds length

A

1,4 glycosidic linkage

33
Q

RLS of gluconeogenesis

Fructose 1, 6 Biphosphate to Fructose 6 phosphate takes place in?

34
Q

Pyruvate to Oxaloacetate to PEP

A

Pyruvate carboxylase
to oxaloacetate to malate… this happens in mitochondria. Malate is able to out of mitochondria. Malate is turned into OAA to
PEP via PEP carboxykinase .

35
Q

glycogen synthase adds what type of linkage? what is needed?

A

1,4 linkage for length and needs glucose 1-P + UDP to turn into UDP glucose. UDP glucose is used along with glycogen synthase

36
Q

branching enzyme adds what type of linkage?

A

1,6 linkage

37
Q

glycogenin molecule has what?

A

Tyr-OH group

38
Q

What does glycogenin do

A

it self flycosolates and takes UDP glucose and releases the UDP and primes the glucose and adds it to glycognenin to make a primed glycogenin

39
Q

primed glycogenin is ready for?

A

glycogen synthesis, via glycogen sythetase and branching enzyme

40
Q

glycogen molecule: A core protein of glycogenin is surrounded by branches of glucose units.

A

glycogenin is surrounded by branches of glucose units.

41
Q

glycogen degradation

glycogen to glucose 1 phosphate via?

A

glycogen phosphorylase

42
Q

g6p can go to..

A

glycolysis, make glucose, ppp–> ribose nadph

43
Q

what enzyme removes 1,4 likage?

A

phosphorylase

44
Q

what enzyme removes 1,6 linkages?

A

alpha 1, 6 glucosidase

45
Q

When blood glucose levels are high, insulin

A

stimulates glycogen synthesis.

46
Q

? regulates blood glucose levels.

A

Glycogen metabolism in liver

47
Q

Phosphorylase a normally binds PP1 (protein phosphatase 1), keeping PP1 inactive. ___causes the dissociation of PP1 from phosphorylase a, which activates __

A

glucose, PP1

48
Q

This dissociated active PP1 then ___glycogen synthase 1, thereby ____.

A

dephosphorylates, activating it

49
Q

At the same time, the inhibition of phosphorylase a by glucose results in a reduced of phosphorylase a on PP1 that now has increased activity to

A

inhibition,activate glycogen synthase.

50
Q

___ Stimulates Glycogen Synthesis in Muscle

51
Q

is responsive to epinephrine.

52
Q

is responsive to glucagon and

53
Q

Can epi and glucagon stimulate glycogen breakdown?

54
Q

activate adenylyl cyclase, leading to a rise in cAMP. cAMP stimulates glycogenolysis to glucose, leading to increased blood glucose levels.

A

Glucagon and beta-agonists

55
Q

beta-agonists do. Glycogenolysis is simulated by?, but since muscle does not synthesize glucose, it converts pyruvate to lactate which is secreted into the bloodstream.

A

beta-agonists do.

56
Q

The highly branched structure of glycogen

A

provides a large number of sites for addition or removal of glucose to facilitate a more rapid response to bodily needs. Its proteinaceous core (glycogenin) is a self-glucosylating enzyme that provides the poly-glucose primer for glycogen synthesis.

57
Q

the rate-limiting steps of glycogen synthesis and degradation, respectively.

A

Glycogen synthase and glycogen phosphorylase catalyzes

58
Q

provides the glucose residues for the synthesis of glycogen.

A

sugar nucleotide, UDP-glucose

59
Q

promote degradation of glycogen through a cAMP-mediated cascade of phosphorylation steps. Receptors for glucagon are found only on liver cells, while epinephrine receptors (adrenergic receptors) are found in both muscle and liver cells.

A

Epinephrine and glucagon

60
Q

Degradation of glycogen in the liver can supply blood glucose because liver contains ? (gluconeogenesis). Muscle does not contain this enzyme. In muscle, breakdown of glycogen is used to generate energy (ATP) through glycolysis.

A

glucose 6-phosphatase

61
Q

Glucose stimulates ___of Glycogen synthase by PP1 to form

A

de-phosphorylation , active Glycogen synthase enzyme

62
Q

Glucose-6-phosphatase deficiency. Final step of gluconeogenesis and glycogenolyis to produce glucose is defected. Growth failure and lactic acidosis; no pathologic muscle symptoms. less glucose at night

A

von gierekes

63
Q

Glycogen debranching enzyme deficiency. Defect in glycogenolyis Myopathies. run out of energy

A

coris disease

64
Q

Glycogen branching enzyme deficiency. Defect in glycogen synthesis. Failure to thrive; death at about age 5 years. No pathologic muscle symptoms.

A

(Anderson disease).

65
Q

Glycogen phosphorylase deficiency. Defect in glycogenolyis. Exercise-induced muscle cramps; rhabdomyolysis (breakdown of damaged skeletal muscle

A

(McArdle disease).

Biochemistry - Block 2 (4 decks)

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