Metabolism of saccharides - exercise -
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Transcript of Metabolism of saccharides - exercise -
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Metabolism of saccharides
- exercise -
Vladimíra Kvasnicová
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Glucose enter the cells by
a) free diffusion
b) facilitated diffusion
c) active transport
d) secondary active transport
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Glucose enter the cells by
a) free diffusion
b) facilitated diffusion
c) active transport
d) secondary active transport
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Insulin-dependent transport of glc into the cell is found in the
a) liver
b) erytrocyte
c) adipose tissue
d) muscle
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Insulin-dependent transport of glc into the cell is found in the
a) liver
b) erytrocyte
c) adipose tissue
d) muscle
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Glucose transport into cells: facilitated diffusion
(protein transporter GLUT – various types)
ERYTROCYTES NERVOUS TISSUE
- insulin-independent transport
The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
HEPATOCYTES
- insulin-independent transport
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FATTY TISSUE MUSCLES
- insulin-DEPENDENT transport
insulin increases number of glc transporters
The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
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The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
Secondary-active transport of GLC: symport with Na+
- small intestine, kidneys
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Glucose from a diet can be used
a) as an energy source for cells
b) for glycogen synthesis
c) for formation of fat (= energy store)
d) as a main substrate for production of NADPH
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Glucose from a diet can be used
a) as an energy source for cells
b) for glycogen synthesis
c) for formation of fat (= energy store)
d) as a main substrate for production of NADPH
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
Glc-6-P !!!
+ NADPH
= hepatocyte
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Glycolysis(= oxidative cleavage of glucose)
a) is located in a mitochondrion
b) can proceed under anaerobic conditions as well
c) produces 2 moles of pyruvate / 1 mole of Glc
d) generates 2 moles of ATP as a net energy acquisition
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a) is located in a mitochondrion
b) can proceed under anaerobic conditions as well
c) produces 2 moles of pyruvate / 1 mole of Glc
d) generates 2 moles of ATP as a net energy acquisition
Glycolysis(= oxidative cleavage of glucose)
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
2
2
Products of aerobic glycolysis
Products of anaerobic glycolysis
NADHwas consumed in
conversion of pyruvate to
lactate
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Enzyme hexokinase
a) catalyzes esterification of glucose
b) has higher affinity to glucose than glucokinase
c) phosphorylates fructose as well
d) is found in a cytoplasm of many cells
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Enzyme hexokinase
a) catalyzes esterification of glucose
b) has higher affinity to glucose than glucokinase
c) phosphorylates fructose as well
d) is found in a cytoplasm of many cells
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
IRREVERSIBLE REACTION
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
The glucokinase has higher value of Kmthan hexokinase glucokinase has lower affinity to glucose
(it needs more glucose to reach the reaction velocity of Vmax/2)
Km Km
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Enzyme 6-phosphofructokinase-1 (PFK-1)
a) is a main regulatory enzyme of glycolysis
b) converts fructose-1,6-bisphosphate to fructose-6-phosphate
c) is activated by citrate and ATP/ADP
d) is regulated by insulin
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Enzyme 6-phosphofructokinase-1 (PFK-1)
a) is a main regulatory enzyme of glycolysis
b) converts fructose-1,6-bisphosphate to fructose-6-phosphate
c) is activated by citrate and ATP/ADP
d) is regulated by insulin
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
IRREVERSIBLE REACTION
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NADH+H+ forming in glycolysis
a) is a coenzyme of oxidoreductases
b) can be reoxidized back to NAD+ in a conversion of pyruvate to lactate
c) can be used in a reduction of malate to oxaloacetate
d) is a source of reducing equivalents enteringa respiratory chain, but only under aerobic conditions
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NADH+H+ forming in glycolysis
a) is a coenzyme of oxidoreductases
b) can be reoxidized back to NAD+ in a conversion of pyruvate to lactate
c) can be used in a reduction of malate to oxaloacetate
d) is a source of reducing equivalents enteringa respiratory chain, but only under aerobic conditions
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
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MALATE-ASPARTATE SHUTTLE
Transport of reducing equivalents to mitochondria
The figure was adopted
from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc.,
New York, 1997. ISBN 0‑471‑15451‑2
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GLYCEROL PHOSPHATE SHUTTLE
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
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2,3-bisphosphoglycerate (2,3-BPG)
a) belongs among energy rich compounds
b) is formed from glyceraldehyde-3-phosphate by phosphorylation using inorganic phosphate
c) can be transformed to 3-phosphoglycerate, ATP is simultaneously formed from ADP
d) is formed only in the liver as a shunt of glycolysis
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2,3-bisphosphoglycerate (2,3-BPG)
a) belongs among energy rich compounds
b) is formed from glyceraldehyde-3-phosphate by phosphorylation using inorganic phosphate
c) can be transformed to 3-phosphoglycerate, ATP is simultaneously formed from ADP
d) is formed only in the liver as a shunt of glycolysis
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2,3-BPG shunt
IN ERYTROCYTES:
2,3-BPG affinity of Hb to O2
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
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ATP is formed in the reactions of glycolysis
a) phosphoenolpyruvate (PEPA) → pyruvate
b) glucose → glucose-6-phosphate
c) fructose-1,6-bisphosphate→ fructose-6-phosphate
d) glyceraldehyde-3-phosphate→ 1,3-bisphosphoglycerate
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ATP is formed in the reactions of glycolysis
a) phosphoenolpyruvate (PEPA) → pyruvate
b) glucose → glucose-6-phosphate ATP is consumed
c) fructose-1,6-bisphosphate = not energy-rich comp.
→ fructose-6-phosphate
d) glyceraldehyde-3-phosphate→ 1,3-bisphosphoglycerate
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
= substrate level phosphorylation(ATP formation using energy released from
cleavage of an energy rich compound = macroergic compound)
IRREVERSIBLE REACTION
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
= substrate level phosphorylation
Pi +
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Pyruvate can be transformed by
a) carboxylation to acetyl-CoA
b) reduction to lactate
c) oxidative decarboxylation to oxaloacetate
d) transamination to aspatate
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Pyruvate can be transformed by
a) carboxylation to acetyl-CoA
b) reduction to lactate
c) oxidative decarboxylation to oxaloacetate
d) transamination to aspatate
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
= transamination
= carboxylation = oxidative decarboxylation
= reduction
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Choose correct statements about regulation of glycolysis
a) it is activated by insulin
b) it is activated by glucagon
c) regulatory enzymes of glycolysis are kinases
d) pH inhibits glycolysis
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Choose correct statements about regulation of glycolysis
a) it is activated by insulin
b) it is activated by glucagon
c) regulatory enzymes of glycolysis are kinases
d) pH inhibits glycolysis
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regulatory enzyme activation inhibition
hexokinase glucose-6-phosphate
glucokinase insulin (induction) fructose-1-phosphate (liver)
fructose-6-phosphate
6-phosphofructo-1-kinase (PFK-1)
main regulatory enzyme
(key enzyme)
ATP / AMP fructose-2,6-bisphosphate ( if insulin / glucagon) insulin (induction)
ATP / AMP citrate acidic pH
pyruvate kinase insulin (induction) fructose-1,6-bisphosphate (feed foreward regulation)
glukagon (repression, inhibition by phosphorylation) ATP / AMP acetyl-CoA
Regulation of glycolysis
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Enzymes of gluconeogenesis(= synthesis of glucose „de novo“)
a) are found in a cytoplasm only
b) are active mainly in a brain and erytrocytes
c) are completely the same as enzymes of glycolysis (catalyze oposite reactions of glycolysis)
d) are not found in the liver
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a) are found in a cytoplasm only
b) are active mainly in a brain and erytrocytes
c) are completely the same as enzymes of glycolysis (they catalyze oposite reactions of glycolysis)
d) are not found in the liver gluconeogenesis proceeds only in the liver and the kidneys
Enzymes of gluconeogenesis(= synthesis of glucose „de novo“)
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (lJan 2007)
in mitochondria only
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
Gluconeogenesis
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Choose substrates of gluconeogenesis
a) acetyl-CoA
b) pyruvate
c) glycerol
d) lactate
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Choose substrates of gluconeogenesis
a) acetyl-CoA it can not be converted to pyruvate
b) pyruvate
c) glycerol
d) lactate
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Cori cycle
and muscle
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
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Glucose-alanine cycle
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
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= tuk
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
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Choose enzymes of gluconeogenesis
a) pyruvate kinase
b) PEP carboxykinase
c) pyruvate carboxylase
d) pyruvate dehydrogenase
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Choose enzymes of gluconeogenesis
a) pyruvate kinase
b) PEP carboxykinase
c) pyruvate carboxylase
d) pyruvate dehydrogenase
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The figure is found at http://faculty.uca.edu/~johnc/pdhrxns.gif (Jan 2006)
Pyruvate DeHydrogenase complex is found in mitochondria
(multienzyme complex, PDH)
the reaction is IRREVERSIBLE
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The reactions participate in gluconeogenesis
a) pyruvate + CO2 → oxaloacetate
b) pyruvate + ATP → phosphoenolypyruvate
c) fructose-1,6-bisphosphate → fructose-6-phosphate + ATP
d) glucose-6-phosphate → glucose + ATP
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The reactions participate in gluconeogenesis
a) pyruvate + CO2 → oxaloacetate
b) pyruvate + ATP → phosphoenolypyruvate
c) fructose-1,6-bisphosphate → fructose-6-phosphate + ATP
d) glucose-6-phosphate → glucose + ATP
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Gluconeogenesis is
a) activated by insulin
b) inhibited by citrate
c) activated by AMP
d) inhibited by glucagon
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Gluconeogenesis is
a) activated by insulin
b) inhibited by citrate
c) activated by AMP
d) inhibited by glucagon
the opposite answers are correct
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regulatory enzyme activation inhibition
pyruvate carboxylase acetyl-Co A cortisol, glucagon (induction)
insulin (repression)
phosphoenolpyruvatecarboxykinase
cortisol, glucagon (induction)
insulin (repression)
fructose-1,6-bisphosphatase
cortisol, glucagon (induction)
AMP / ATP fructose-2,6-bisphosphate ( if insulin / glucagon) insulin (repression)
glucose-6-phosphatase
cortisol, glucagon (induction)
insulin (repression)
Regulation of gluconeogenesis
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Metabolism of glycogen
a) is regulated by glycogen synthase and glycogen phosphorylase
b) is located in a cytoplasm
c) is regulated by insulin
d) proceeds on reducing ends of glycogen molecule
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Metabolism of glycogen
a) is regulated by glycogen synthase and glycogen phosphorylase
b) is located in a cytoplasm
c) is regulated by insulin
d) proceeds on reducing ends of glycogen molecule
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
Metabolism of glycogen
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During glycogen synthesis(= glycogenesis)
a) Glc-6-P is transformed to UDP-6-glc
b) glycogen synthase participates in a formation of both (1→4) and (1→6) glycosidic bonds
c) a macroergic phosphate is consumed
d) is glycogen synthase activated by glucagon
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a) Glc-6-P is transformed to UDP-6-glc
b) glycogen synthase participates in a formation of both (1→4) and (1→6) glycosidic bonds
c) a macroergic phosphate is consumed
d) is glycogen synthase activated by glucagon
During glycogen synthesis(= glycogenesis)
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
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During degradation of glycogen within cells
(= glycogenolysis)
) (1→6) glycosidic bonds are split by glycogen phosphorylase
b) glucose is transfered to phosphate: glc-1-P is formed as a product of the degradation
c) (1→4) bonds are split hydrolytically
d) 1 ATP is consumed if 1 glc is released
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During degradation of glycogen within cells
(= glycogenolysis)
) (1→6) glycosidic bonds are split by glycogen phosphorylase
b) glucose is transfered to phosphate: glc-1-P is formed as a product of the degradation
c) (1→4) bonds are split hydrolytically
d) 1 ATP is consumed if 1 glc is released
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
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If glycogenolysis is followed by glycolysis
a) the net gain of the anaerobic glycolysis is3 ATP
b) the process is called gluconeogenesis
c) both the cytoplasmatic and mitochondrial enzymes participate in the reactions
d) oxaloacetate is formed as an intermediate
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If glycogenolysis is followed by glycolysis
a) the net gain of the anaerobic glycolysis is3 ATP
b) the process is called gluconeogenesis
c) both the cytoplasmatic and mitochondrial enzymes participate in the reactions
d) oxaloacetate is formed as an intermediate
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)
glycogen glucose
ATP
ADPPi
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regulatory enzyme activation inhibition
glykogen phosphorylase(glycogen degradation)
glucagon, adrenaline (phosphorylation)
ATP / AMP Ca2+ (muscle)
ATP / AMP glucose-6-phosphate glucose
glykogen synthase(glycogen synthesis)
insulin (induction) glucose-6-phosphate
glucagon, adrenaline (phosphorylation)
Regulation of glycogen metabolism
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Pentose cycle(= Hexose MonoPhosphate Pathway,
HMPP)
a) is located in a cytoplasm
b) includes direct oxidation of glucose monophosphate
c) is a shunt of glycolysis (products of HMPP can enter glycolysis)
d) produces pentoses
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Pentose cycle(= Hexose MonoPhosphate Pathway,
HMPP)
a) is located in a cytoplasm
b) includes direct oxidation of glucose monophosphate
c) is a shunt of glycolysis (products of HMPP can enter glycolysis)
d) produces pentoses
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The figure is found at http://www.richmond.edu/~jbell2/14F34.JPG (Dec 2006)
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Choose enzymes of HMPP
a) transketolase
b) transaminase
c) glucose-6-phosphate dyhydrogenase(glc-6-P DH)
d) pyruvate carboxylase
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Choose enzymes of HMPP
a) transketolase
b) transaminase
c) glucose-6-phosphate dyhydrogenase(glc-6-P DH) = regulatory enzyme
d) pyruvate carboxylase
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Pentose cycle
a) produces NADPH which can be oxidized in a respiratory chain → energy is produced
b) generates saccharides used in a glycoprotein synthesis
c) forms ribose-5-phosphate a substrate of nucleic acids synthesis
d) forms fru-6-P and glyceraldehyde-3-P which can enter glycolysis or gluconeogenesis
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Pentose cycle
a) produces NADPH which can be oxidized in a respiratory chain → energy is produced
b) generates saccharides used in a glycoprotein synthesis
c) forms ribose-5-phosphate a substrate of nucleic acids synthesis
d) forms fru-6-P and glyceraldehyde-3-P which can enter glycolysis or gluconeogenesis
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If NADPH accumulates
a) oxidative part of HMPP is inhibited
b) ribose-5-phosphate can not be synhesized
c) glc-6-P dehydrogenase is activated
d) the reversible reactions of the HMPP can only proceed
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If NADPH accumulates
a) oxidative part of HMPP is inhibited
b) ribose-5-phosphate can not be synhesized
c) glc-6-P dehydrogenase is activated
d) the reversible reactions of the HMPP can only proceed
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The figure is found at http://web.indstate.edu/thcme/mwking/pentose-phosphate-pathway.html (Dec 2006)
IRREVERSIBLE
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The figure is found at http://web.indstate.edu/thcme/mwking/pentose-phosphate-pathway.html (Dec 2006)
intermediates of glycolysis
synthesis of
nucleotides
REVERSIBLE
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Regulation of HMPP
• on the level of substrates availability and products consumption
NADPH / NADP+
reaction using NADP+ are inhibited by lack
of the coenzyme
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Fructose
a) is metabolized mainly in the liver
b) can be transformed to fru-6-P by fructokinase
c) can be formed from sorbitol as well
d) can be transformed to glucose
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Fructose
a) is metabolized mainly in the liver
b) can be transformed to fru-6-P by fructokinase
c) can be formed from sorbitol as well
d) can be transformed to glucose
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Metabolism of fructose in the liver
The figure is found at http://web.indstate.edu/thcme/mwking/glycolysis.html (Jan 2007)
glycolysis or gluconeogenesis
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The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
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When Fru is converted to Fru-1-P
a) it can be split by an aldolase to glyceraldehyde and dihydroxyacetone phosphate
b) is fructose metabolised in glycolysis faster then glucose
c) glyceraldehyde made by spliting of fru-1-P can be converted to glycerol
d) glucokinase can be activated by fru-1-P
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When Fru is converted to Fru-1-P
a) it can be split by an aldolase to glyceraldehyde and dihydroxyacetone phosphate
b) is fructose metabolised in glycolysis faster then glucose
c) glyceraldehyde made by spliting of fru-1-P can be converted to glycerol
d) glucokinase can be activated by fru-1-P
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Glucose can be converted to
a) galactose: glc-6-P → gal-6-P
b) fructose: glc → glucitol → fru
c) glucuronic acid: UDP-glc + 2 NAD+ → UDP-glukuronate + 2 NADH+H+
d) ribose: glc-6-P → → ribulose-5-P → rib-5-P
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Glucose can be converted to
a) galactose: glc-6-P → gal-6-P
b) fructose: glc → glucitol → fru
c) glucuronic acid: UDP-glc + 2 NAD+ → UDP-glukuronate + 2 NADH+H+
d) ribose: glc-6-P → → ribulose-5-P → rib-5-P
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Metabolism of galactose
The figure is found at http://web.indstate.edu/thcme/mwking/glycolysis.html (Jan 2007)
epimerization
proceeds on the level of UDP-
derivatives
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The figure is found at http://www.kumc.edu/research/medicine/biochemistry/bioc800/car02fra.htm (Jan 2007)