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Biochemistry Block 1 > Glycolisis > Flashcards

Glycolisis Flashcards

1
Q

what is the central pathway of glucose metabolism in all cells?

A

GLYCOLYSIS

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2
Q

When pyruvate is converted into CO2 and H20 glycolysis in this setting is termed ?

A

aerobic glycolisis

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3
Q

when pyruvate is reduced to lactic acid, glycolysis is termed?

A

anaerobic glycolysis

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4
Q

which cell in our bodies relies exclusively on blood glucose?

A

RBC’S

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5
Q

Which cell in our bodies has the lowest rate of ATP synthesis?

A

RBC’S

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6
Q

How many ATPs are invested to prime the metabolism of glucose?

A

2 ATP’s

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7
Q

what is the role of GLUT 1 in glycolysis?

A

Glucose is taken up into the RBC via this facilitated transporter.

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8
Q

how GLUCOSE-6-PHOSPHATE is obtain?

A

via phosphorylation of glucose

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9
Q

what is the role of enzyme HEXOKINASE?

A

catalyzed Glucose

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10
Q

Which enzyme helps in the conversion of Glucose 6 phosphate into fructose 6 phosphate?

A

PHOSPHOGLUCOSE ISOMERASE

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11
Q

Which regulatory enzymes are important for glycolysis?

A

HEXOKINASE AND PHOSPHOFRUCTOKINASE 1(PFK-1)

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12
Q

Which enzyme determines the critical commitment step in glycolysis?

A

PFK-1

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13
Q

What is the product after phosphorylating glucose 6 phosphate?

A

Fructose 6 phosphate F6P

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14
Q

Which enzyme catalyzed the reaction from Fru-6-P into FRUCTOSE 1,6 BIPHOSPHATE?

A

PHOSPHOFRUCTOKINASE-1(PFK1)

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15
Q

fructose 1,6 BP is cleaved in the middle by which enzyme?

A

ALDOLASE

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16
Q

dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3 phosphate( GA3P) are the yield products of ?

A

ALDOLASE REACTION

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17
Q

Which enzyme catalyzes the interconversion reaction of DHAP?

A

TRIOSEPHOSPHATE ISOMERASE

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18
Q

provide pathway for the investment stage of glycolysis?

A

glucose-(hexokinase)-glucose 6 phosphate-(phosphoglucose isomerase)- fructose 6 phosphate-( phosphofructosekinase-1)- fructose 1.6 biphosphate.

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19
Q

provide pathway for the splitting stage of glycolysis?

A

(aldose)-dihydroacetone phostate-(triosephosphate isomerase)-glyceraldehyde 3 phosphate or (aldose)-glyceraldehyde 3.phosphate.

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20
Q

describe substrate level phosphorylation

A

X-P + ADP—> X+ ATP

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21
Q

When a high energy phosphate compound transfers its phosphate to ADP , yielding ATP is called?

A

SUBSTRATE LEVEL PHOSPHORYLATION

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22
Q

which enzyme catalyzes a redox reaction, forming a high energy acyl phosphate compound?

A

GAPDH - Glyceraldehyde 3 phosphate dehydrogenase

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23
Q

after GAPDH Catalyzes the redox reaction we get as a yield product?

A

1.3-BISPHOSPHOGLYCERATE and coenzyme NAD+ is reduced to NADH

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24
Q

iodoacetamide, p-chloromecuribenzoate and N-ethylmaleimide inhibits which enzyme?

A

GAPDH

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25
Q

which enzyme catalyzes transfer of the phosphate group from the high energy acyl phosphate of 1.3 BPG to ADP, forming ATP?

A

Phosphoglycerate kinase (PGK)

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26
Q

Which enzyme converts 3 phosphoglycerate into 2 phosphoglycerate?

A

PHOSPHOGLYCERATE MUTASE

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27
Q

What kind of enzymes catalyze the transfer of functional groups within a molecule?

A

MUTASES

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28
Q

2-phosphoglycerate undergoes a dehydration reaction to yield?

A

PHOSPHOENOLPYRUVATE (PEP)

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29
Q

Which enzyme catalyzes 2-phosphoglycerate ?

A

ENOLASE

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30
Q

Phosphoglycerate kinase and pyruvate kinase catalyze what kind of reaction?

A

substrate level phosphorylation reactions

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31
Q

arsenate inhibits what?

A

substrate level phosphorylation of GAPDH and PGK

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32
Q

Fluoride is used in blood collection to prevent?

A

False diagnosis of hypoglycemia and acidemia

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33
Q

fluoride inhibits which enzyme?

A

enolase

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34
Q

clinical
child presented with jaundice
abdominal tenderness
labs: low hematocrit and hemoglobin concentration
normochromatic erythrocytes with normal morphology
mild reticulocytosis
serum bilirubin was increased

whats the diagnosis?

A

pyruvate kinase deficiency is the most common of the hemolytic anemia , due to deficiency in glycolytic enzyme

35
Q

LDH(lactate dehydrogenase) regenerates which substrate

A

NADH+ consumed in the GAPDH reaction producing lactate

36
Q

what is the end product of anaerobic glycolisis?

37
Q

during fermentation pyruvate is converted into what?

38
Q

the NADH produced in the GAPDH reactions in reoxidized by ?

A

ALCOHOL DEHYDROGENASE

39
Q

Streptococcus mutans and lactobacillus are what kind of bacteria?

A

anaerobic bacteria that colonizes the oral cavity and contribute to development of dental caries

40
Q

mention the kinease reactions at which glycolysis is regulated allosterically?

A

hexokinase, phosphofructokinase-1(PFK1) and pyruvate kinase.

41
Q

which molecule is both a substrate and an allosteric inhibitor?

42
Q

which enzyme is present at the lowest activity of all glycolitic enzymes?

A

hexokinase

43
Q

which site is the primary site of regulation of glycolysis?

A

phosphofructokinase-1 PFK1

44
Q

PFK1 is strongly inhibited by?

A

ambient ATP

45
Q

Which enzyme relives the inhibition of PFK1 by ATP?

A

AMP and ADP

46
Q

what decreases the Km for substrate FRU6P?

A

AMP and ADP

47
Q

The overall activity of PFK1 and thus the rate of glycolysis, depends on the cell’s?

A

(AMP+ADP)/ATP concentration ratio products are interconvertible by the ADENYLATE KINASE REACTION

48
Q

The phosphorylation of ADP during glycolysis and then of AMP by the adenylate kinase reaction , gradually restores what?

A

the ATP concentration or energy charge

49
Q

the enzyme PYRUVATE KINASE in the liver is allosterically activated by?

A

FRUCTOSE-1,6 BP

50
Q

Mention the enzymes involved in regulation of the glycolysis?

A

hexokinase, PFK-1, and pyruvate kinase

51
Q

mention the characteristics of a regulatory enzyme?

A

dimeric or tetramic whose structure and activity are responsive to allosteric modulators

  • low Vmax
  • catalyze irreversible reactions
52
Q

the pathway for biosynthesis and degradation of 2,3 bisphopsphoglycerate (2-3 BPG) bypasses which reaction?

A

the phosphoglycertae kinase reaction

53
Q

the overall yield of ATP in the 2,3 BPG pathway is ?

54
Q

which enzyme catalyzes the conversion of 1,3 BPG to 2,3-BPG ?

A

BPG mutase

55
Q

the presence of 2,3 BPG in the tRBC explains the observation that?

A

O2 afinnity of purified HbA is greater than that of whole RBC’S

56
Q

2,3BPG concentrations increases in the RBC during what ?

A

adaptation to high altitude
chronic obstructive pulmonary disease and in anemia
promotes the release of O2 to tissues when O2 tension and saturation of hemoglobin decreases int he lung

57
Q

which type of hemoglobin is less sensitive to the effects of 2,3 BPG?

A

FETAL HEMOGLOBIN OF HbF

58
Q

The byproduct 2,3 BPG is a negative allosteric effector of ?

A

O2 affinity of Hb , decreases the O2 affinity of hemoglobin, promoting the release of O2 in peripheral tissues.

59
Q

what is the pentose phosphate pathway ?

A

is the source of ribose phosphate for synthesis of RNA and DNA

60
Q

What is the major product of pentose phosphate pathway in all cells?

61
Q

Where does active lipid biosynthesis occurs?

A

ex: liver, adrenal cortex, or lactating mammary glands .

62
Q

in pentose phosphate pathway NAPDH is use in ?

A

redox reactions required for biosysnthesis of cholesterol, bile and steroid hormones and triglycerides

63
Q

the liver uses NAPDH besides biosynthesis of cholesterol,bile and steroid hormones and triglycerides for what else?

A

hydroxylation reactions involved in the detox and excretion of drugs

64
Q

the primary use of NAPDH is

A

reduction of cysteine cofactor for antioxidant protection

65
Q

the pentose phosphate pathway is divided into how many stages ?

A

two

  1. irreversible redox stage yields to both NADPH and pentose phosphates
  2. reversible interconversion stage , excess of pentose phisphates are converted into glytolytic intermediates
66
Q

in the redox stage of the pentose phosphate pathway(synthesis of NADPH)…NAPDH is synthesized by?

A

two dehydrogenases in the first and third reactions

67
Q

Glc-6P dehydrogenase(G6PDH) reaction produces?

A

NADPH by oxidation of Glc-6-p to 6 phosphogluconic acid lactone

68
Q

Glc 6P is oxidized to ______ in the pentose phosphate pathway?

A

6 phosphogluconic acid lactone

69
Q

6 phosphogluconic acid lactone is hydrolyzed by?

70
Q

oxidative decarboxylation of 6 phosphogluconate is catalyzed by?

A

6 phosphogluconate dehydrogenase

71
Q

glycolytic enzymes (GAPDH and LDH) use only ?

72
Q

Pentose phosphate pathway enzymes use only ?

73
Q

Why high levels of both NAD+ and NADPH can exist simultaneosly in the same compartment ?

A

there are no enzymes in the RBC that catalyze the reduction of NAD+ by NADPH

74
Q

in the interconversion stage of the pentose phosphate pathway in cells with active nucleic acid synthesis
RIBULOSE 5-Phosphate from the 6 phopsphoglucose dehydrogenase reaction is ?

A

isomerized to ribose 5 phosphate for synthesis of ribo and deoxyribonucleotides for RNA and DNA

75
Q

in the interconversion stage of the pentose phosphate pathway in cells that are nondividing , the pentose phossphatases are?

A

rerouted back to glycolysis

76
Q

transkelotase in the interconversion stage of pentose phosphate is a ?

A

thiamine depended enzyme

77
Q

transaldolase in the interconversion stage of pentose phosphate pathway acts similarly to?

A

aldolase in glycolysis
-except that the 3 carbon units is transferred to another sugar , rather than released as a free TRIOSE PHOSPHATE for glycolysis.

78
Q

the pentose phosphate pathway protects against?

A

OXIDATIVE DAMAGE IN THE RED CELL

79
Q

The reduced form of GLUTATHIONE(GSH) is an essential coenzyme for?

A

protection of the cell against a range of oxidative and chemical insults

80
Q

GSH has a range of protective functions, mention them …

A
  1. glutathione peroxidase(GPx) - detox of hydrogen peroxide and organic lipid peroxides int he cytosol and cell membranes
  2. intracellular sulfhydryl buffer maintaining exposed SH groups on proteins and ezymes in the reduce state.
81
Q

in red blood cells GSH maintains the SH groups in the reduced state by?

A

inhibiting disulfide crosslinking of the protein

82
Q 
Clinical
-patient complaining weakness
-urine had recently become dark(unexplainably)
physical examination:
-slightly jaundice sclera
labs:
- low hematocrit
-high reticulocyte count 
- increased levels of bilirubim

extras:
patient received inmunizations and Rx for antimalarial drugs last week

possible diagnosis?

A

GLUCOSE 6 PHOSPHATE DEFICIENCY causes hemolytic anemia

  • primaquineand related antimalarials undergo redox reactions in the cell—–large quatities of reactive oxygen species (ROS)
  • bilirubim overloads hepatic detoxification pathways and also accumulates in plasma and tissues causing jaundice
  • Hb spills over into urine, resulting hematuria and dark colored globin
  • G6PDH is typically asymptomatic , except in response to an oxidative challenge, which was induced by drugs(antimalarials, sulfa drugs, diet(fava beans) or severe infection
83
Q

What does ROS(reactive oxygen species) causes?

A

oxidation of SH groups in hemoglobin and peroxidation of membrane lipids

Biochemistry Block 1 (6 decks)

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