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Biochemistry 2 > pentose phosphate pathway & glyconeogenesis > Flashcards

pentose phosphate pathway & glyconeogenesis Flashcards

1
Q

where does the PPP takes place?

A

in the cytosol

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2
Q

Two ……………………… oxidative reactions followed by series of …………………….. sugar- phosphate conversion.

A

irreversible

reversible

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3
Q

what is the main point of PPP?

A

production of ribose-5-phosphate which is important is the biosynthesis of nucleotides.

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4
Q

3 reactions to produce ribulose 5-phophate, 1 mole of …………… and 2 …………….

A

CO2

NADPH

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5
Q

the PPP has 3 irreversible reactions that need to happen, why do they need to happen, what is their importance?

A

A) liver, lactating mammary
gland and adipose tissue ->FAs
B)testes, ovaries, adrenal cortex ->steroids
C)RBC -> GSH

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6
Q

which enzyme catalyzes glucose-6-phosphate to 6- phospho-gluconolactone?

A

Glucose 6-phosphate dehydrogenase (G6PD)

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7
Q

what can inhibit Glucose 6-phosphate dehydrogenase (G6PD)?

A

NADPH, its a potent inhibitor for this enzyme

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8
Q

As [NADPH]/[NADP] decreases, pathway activity of Glucose 6-phosphate dehydrogenase ………………………….

A

increases

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9
Q

what is the enzyme used to convert 6- phospho - gluconolactone to 6- phosphogluconate?

A

6- phospho-gluconolactone hydrolase.

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10
Q

Oxidative decarboxylation of 6- phospho-gluconate is catalyzed by ……………………………………………..

A

6 phospho-gluconate dehydrogenase

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11
Q

Pentose sugar-phosphate is produced and a second molecule of ………………………… is produced.

A

NADPH

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12
Q

Why do we need NADPH?

A 
A. reductive biosynthesis
B. Reduction of Hydrogen Peroxides
C. Phagocytosis Cells
by White Blood
D. Synthesis Oxide
of Nitric
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13
Q

In hepatocytes,
• [NADP+]/[NADPH] ~ ………….
• [NAD+]/[NADH] ~…………..

what does this means

A

0.1
1000
this means that the liver contains a high ratio of NADPH

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14
Q

Reduction of molecular oxygen yields reactive oxygen species (ROS), what do they cause usually? what does the cells do regarding this?

A

ROS can cause reperfusion injury, inflammatory disease, cancer, and aging.
Cells have mechanisms to minimize the toxic potential of these chemicals.

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15
Q

how do we remove ROS from our system?

A

Reduced Glutathione

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16
Q

Unlike other types of cells, RBCs don’t have alternate sources to convert ROS to harmless products, what do they do instead?

A

RBC totally depends on the PPP for their supply of NADPH

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17
Q

give some examples of antioxidant chemicals.

A

Ascorbate, B-carotene, vitamin E.

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18
Q

does antioxidant chemicals treat cancer?

A

NO!
Clinical trials with antioxidants have failed to show clear beneficial effects
Moreover, taking B-carotene as a supplement increased the rate of lung cancer in smokers.

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19
Q

what is respiratory burst and why does it occur?

A 
Respiratory burst (RB) is a rapid increase in the production of reactive oxygen species (ROS) during the phagocytosis of microbes or bacteria.
it occurs to kill bacteria.
20
Q

……………………… is unstable free radical gas

A

nitric oxide

21
Q

what are the uses of nitric oxide?

A

this gas reacts rapidly with oxygen and is being converted to reactive oxygen species ROS
the uses of it are to relax smooth muscle, prevent platelet aggregation, functions as a neurotransmitter in the brain

22
Q

true or false

G6PD deficiency and/or malfunction is hereditary disease.

A

true

23
Q

true or false

It affects more than 900 million world wide. It has highest prevalence in western region , Mediterranean, Europe and Africa.

A

false

It affects more than 400 million world wide. It has highest prevalence in Middle East, Mediterranean, Asia and Africa.

24
Q

which cell is mostly affected by G6PD deficiency?

A

G6PD Deficiency can be seen in all cell types but RBC are greatly affected

25
Q

what are the results of G6PD deficiency? (note: results means diseases)

A

Hemolytic anemia and Heinz bodies

26
Q

What are the Precipitating Factors in Glucose 6 Phosphate Dehydrogenase?

A
  1. oxidant drugs
  2. favism
  3. Infection
27
Q

what happen if the glucose-6-phophate dehydrogenase goes under a genetic mutation?

A

its gets worse and it can cause hemolytic anemia

28
Q

where does the 1st step of gluconeogenesis takes place?

A

in the mitochondria

29
Q

why is the Pyruvate Carboxylase called ABC enzymes?

A

(ATP, Biotin and CO2 source)

30
Q

why is the OAA reduced to malate first?

A

so it can cross the mitochondria.

It is reconverted to OAA which is decarboxylated and phosphorylated to PEP in the cytosol by PEP- carboxy kinase (PEPCK)

31
Q

Fructose 1,6-bisphosphatase is regulated by ……………………… and …………………….

A 
adenosine monophosphate (AMP)
fructose 2,6-bisphosphate.
32
Q

As AMP increase, Fructose 1,6-bisphosphatase is ………………….
As fructose 2,6-bisphosphate increase, Fructose 1,6-bisphosphatase is ………………….

A

Inhibited

Inhibited

33
Q

True or false

Liver and kidneys are the only organs that release free glucose from glucose 6-phosphate.

A

True

34
Q

True or false

Glucose 6-phosphatase found only in gluconeogenic cells.

A

True

35
Q

True or false

Glycolysis and Gluconeogenesis pathways are nonreciprocally regulated.

A

false

Glycolysis and Gluconeogenesis pathways are reciprocally regulated.

36
Q

what is the product of gluconeogenesis?

A

glucose + 4 ADP+ 2 GDP + 2 NAD+

37
Q

Low level of fructose 2,6- bisphosphate results in what ?

A

results in the inhibition of PFK-1 favoring gluconeogenesis

38
Q

the glucagon mainly inhibits or triggers gluconeogenesis?

A

triggers it.

39
Q 
all of the following regulate glycogenesis  except :
A. substrate availability 
B. acetyl CoA
C. AMP
D. glycolysis
A

D

it’s glucagon not glycolysis

40
Q

does an Increased concentration of Acetyl CoA promotes gluconeogenesis? explain?

A

Increased concentration of Acetyl CoA promotes conversion of AcetylCoA to OAA for gluconeogenesis.

41
Q

which of the following is correct?
A. Glycolysis, a process by which cells can extract a limited amount of energy from glucose under anaerobic conditions
B. Gluconeogenesis, a process by which cells can use a variety of metabolites for the synthesis of glucose
C. Pentose phosphate pathway, a process by which cells can generate reducing power (NADPH) that is needed for the biosynthesis of various compounds
D. The differences between glycolysis and gluconeogenesis is that they are regulated in reciprocal way
E. all off the above

A

E

42
Q 
Which enzyme of gluconeogenesis requires biotin as a coenzyme?
A. PEP carboxykinase
B. Glucose 6-phosphatase 
C. Aldolase
D. Pyruvate carboxylase
E. Pyruvate kinase
A

D. Pyruvate carboxylase

43
Q 
An enzyme used in both glycolysis and gluconeogenesis is:
A. 3-phosphoglycerate kinase. 
B. glucose 6-phosphatase.
C. hexokinase.
D. phosphofructokinase-1.
E. pyruvate kinase
A

A. 3-phosphoglycerate kinase.

44
Q

Which one of the following statements about gluconeogenesis is false?
A. For starting materials, it can use carbon skeletons derived from certain amino acids.
B. It employs the enzyme glucose 6-phosphatase.
C. It is one of the ways that mammals maintain normal blood glucose levels between meals.
D. It requires metabolic energy (ATP or GTP).
E. It consists entirely of the reactions of glycolysis, operating in the reverse direction.

A

E

45
Q

Which of the following statements about the pentose phosphate pathway is correct?
A. It generates 36 mol of ATP per mole of glucose consumed.
B. It generates 6 moles of CO2 for each mole of glucose consumed
C. It is a reductive pathway; it consumes NADH. D. It is present in plants, but not in animals.
E. It provides precursors for the synthesis of nucleotides.

A

E

Biochemistry 2 (7 decks)

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