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Sem 1: PATH20000 > Lecture 16: Glycolysis and Gluconeogenesis > Flashcards

Lecture 16: Glycolysis and Gluconeogenesis Flashcards

1
Q

In the mouth, _______\______\__ breaks α1,4 bonds forming dextrans

A

In the mouth, Salivary​ amylase breaks α1,4 bonds forming dextrans

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2
Q

_______________: cleaves α1,4 bonds, products maltose, isomaltose, tri and oligosaccharides

A

Pancreatic α-amylase: cleaves α1,4 bonds, products maltose, isomaltose, tri and oligosaccharides

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3
Q

_______\_ cleaves α1,6 bond of branched oligosaccharides

A

Isomaltase cleaves α1,6 bond of branched oligosaccharides

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4
Q

α-glucosidase/_____\_ cleave non-reducing ends of oligosaccharides and α1,4 bond of maltose to produce glucose monomers

A

α-glucosidase/maltase cleave non-reducing ends of oligosaccharides and α1,4 bond of maltose to produce glucose monomers

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5
Q

________\_–converts sucrose to glucose + fructose

A

Sucrase–converts sucrose to glucose + fructose

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6
Q

_____\_ -converts lactose to glucose + galactose

A

Lactase -converts lactose to glucose + galactose

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7
Q

Insulin _______ glucose while glucagon, adrenaline, cortisol ______ plasma glucose levels

A

Insulin reduces glucose while glucagon, adrenaline, cortisol increase plasma glucose levels

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8
Q

Failure to maintain normal glucose levels above ___________results in __________\_(shortage of glucose to the brain) and can result in loss of consciousness, brain damage, and death.

A

Failure to maintain normal glucose levels above 3-3.5mmol/L results in neuroglycopenia(shortage of glucose to the brain) and can result in loss of consciousness, brain damage, and death.

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9
Q

Insulin _________\_ target proteins

Glucagon ________\_ target proteins

A

Insulin dephosphorylates target proteins

Glucagon phosphorylates target proteins

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10
Q

________ and ________ cells are only two cell types that have insulin responders

_________ sucks up more insulin

A

Muscle and Adipose cells are only two cell types that have insulin responders

Muscle sucks up more insulin

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11
Q

The liver uses _________ for the synthesis of fatty acids for triglyceride

–active in fed state (insulin) and inactivated in fasting state (glucagon)

A

The liver uses glycolysis for the synthesis of fatty acids for triglyceride

–active in fed state (insulin) and inactivated in fasting state (glucagon)

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12
Q

Metabolic Fuels for various cells/tissues

  • RBC -can only utilize ______________\_
  • Muscle –oxidizes glucose and stores ______\_. Can switch to FA oxidation during fasting.
  • Adipose tissue –takes up glucose and fatty acids where they are converted to TAGs and stored. Can utilize FAs as a fuel source during fasting.
  • Liver –utilizes FA oxide during fasting

Excess glucose can be converted to the ________ molecule of triacylglycerol

Acetyl CoA from glycolysis can form the substrate for de novo lipogenesis

A

Metabolic Fuels for various cells/tissues

  • RBC -can only utilize glucose/anaerobic glycolysis
  • Muscle –oxidizes glucose and stores glycogen. Can switch to FA oxidation during fasting.
  • Adipose tissue –takes up glucose and fatty acids where they are converted to TAGs and stored. Can utilize FAs as a fuel source during fasting.
  • Liver –utilizes FA oxide during fasting

Excess glucose can be converted to the Glycerol molecule of triacylglycerol

Acetyl CoA from glycolysis can form the substrate for de novo lipogenesis

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13
Q

Metabolic Activity During Fasting

  • Heart preferentially utilizes _________\_
  • Adipose undergoes lipolysis –released fatty acids converted to ketones by the liver. _______\_ used for gluconeogenesis
  • Liver -maintains blood glucose by gluconeogenesis (4-6h after) fasting) or glycogenolysis (induced 2-3h after fasting). The liver cannot utilize ________ for energy purposes
  • Muscle releases amino acids during fasting for _________\_. Utilizes fatty acids and ketones for its own fuel source.
  • Brain can switch from using glucose to ketone bodies during prolonged fasting –does this to spare muscle wasting. The brain cannot utilize fatty acids as they don’t cross the BBB
A

Metabolic Activity During Fasting

  • Heart preferentially utilizes fatty acids
  • Adipose undergoes lipolysis –released fatty acids converted to ketones by the liver. Glycerol used for gluconeogenesis
  • Liver -maintains blood glucose by gluconeogenesis (4-6h after) fasting) or glycogenolysis (induced 2-3h after fasting). The liver cannot utilize ketone bodies for energy purposes
  • Muscle releases amino acids during fasting for gluconeogenesis. Utilizes fatty acids and ketones for its own fuel source.
  • Brain can switch from using glucose to ketone bodies during prolonged fasting –does this to spare muscle wasting. The brain cannot utilize fatty acids as they don’t cross the BBB
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14
Q

Glycolysis is the breaking down of glucose. _______ a three-carbon carboxylic acid is the end product of glycolysis (2 moles of pyruvate formed per 1 mole of glucose)

A

Glycolysis is the breaking down of glucose. Pyruvate a three-carbon carboxylic acid is the end product of glycolysis (2 moles of pyruvate formed per 1 mole of glucose)

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15
Q

Glucose is converted into a storage carbohydrate known as glycogen in a process called __________\_. ________\_ is the production of glucose 6-phosphate by splitting a glucose monomer from glycogen by adding an inorganic phosphate whereas _________\_ is the metabolic process by which glucose is formed from non-carbohydrate precursors in the _______.

A

Glucose is converted into a storage carbohydrate known as glycogen in a process called glycogenesis. Glycogenolysis is the production of glucose 6-phosphate by splitting a glucose monomer from glycogen by adding an inorganic phosphate whereas gluconeogenesis is the metabolic process by which glucose is formed from non-carbohydrate precursors in the liver.

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16
Q

Glucose is taken up into erythrocytes and brain via _____\_ (insulin-independent) transporter

Glucose taken up into beta cells via _____\_ on the liver and beta cells stimulates insulin secretion.

Glucose is taken up into adipocytes and muscle cells in response to insulin via the __________\_

A

Glucose is taken up into erythrocytes and brain via GLUT1 (insulin-independent) transporter

Glucose taken up into beta cells via GLUT2 on the liver and beta cells stimulates insulin secretion.

Glucose is taken up into adipocytes and muscle cells in response to insulin via the GLUT4 transporter

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17
Q

Aerobic glycolysis/respiration –pyruvate reduced completely to CO2 and H20 in cells possessing mitochondria and sufficient oxygen (______ATP)

Anaerobic glycolysis/respiration –pyruvate reduced to lactic acid (___ ATP)

A

Aerobic glycolysis/respiration –pyruvate reduced completely to CO2 and H20 in cells possessing mitochondria and sufficient oxygen (36-38 ATP)

Anaerobic glycolysis/respiration –pyruvate reduced to lactic acid (2 ATP)

18
Q

Pyruvate Kinase Deficiency is responsible for ________\_

A

Pyruvate Kinase Deficiency is responsible for hemolytic anemia

  • Varies significantly in severity –little intervention to transfusion requirements
  • RBCs are broken down prematurely resulting in anemia–gathered by spleen resulting in enlargement of the spleen
19
Q

In order to replenish NAD+ (an important oxidizing agent that accepts electrons from other molecules and is reduced) in the cell, pyruvate is reduced to lactate by the enzyme ___________\_ under anaerobic conditions. Most lactate in blood is retrieved by the liver and used as a substrate for gluconeogenesis

A

In order to replenish NAD+ (an important oxidizing agent that accepts electrons from other molecules and is reduced) in the cell, pyruvate is reduced to lactate by the enzyme lactate dehydrogenase under anaerobic conditions. Most lactate in blood is retrieved by the liver and used as a substrate for gluconeogenesis

20
Q

Normal ranges of lactate in blood <2mmol/s, values above 4-5mmol/L indicative of __________\_ often a result of hypoxia

A

Normal ranges of lactate in blood <2mmol/s, values above 4-5mmol/L indicative of Lactic Acidosis ​often a result of hypoxia

21
Q

_____________\_ –found in most tissues but is Glucokinase the liver

  • Provides glucose-6-phosphate for ATP production
  • Experiences auto-feedback inhibition by its product glucose-6-phosphate, but not so in the liver. Why?
A

Hexokinase –found in most tissues but is glucokinase the liver

  • Provides glucose-6-phosphate for ATP production
  • Hexokinase experiences auto-feedback inhibition by its product glucose-6-phosphate (Not glucokinase as phosphorylation of glucose is also important for glucose storage as glycogen and for the generation of acetyl CoA from glucose as a building block for de novo lipogenesis)
22
Q

_____________:

  • Found in liver and pancreas. Very active after a meal but inactive during periods of fasting.
  • Induced by insulin and not inhibited by glucose-6-phosphate
A

Glucokinase:

  • Found in liver and pancreas. Very active after a meal but inactive during periods of fasting.
  • Induced by insulin and not inhibited by glucose-6-phosphate
23
Q

Pyruvate kinase-

  • Activated by _____ 1,6 bisphosphate and inhibited by alanine and by _______\_ in the liver during fasting when glucagon is high
  • Inhibition of pyruvate kinase results in switch towards __________\_
  • Activated in the fed state/insulin by _____________\_
A

Pyruvate kinase –active in its dephosphorylated form

  • Activated by fructose 1,6 bisphosphate and inhibited by alanine and by phosphorylation in the liver during fasting when glucagon is high (PKA)
  • Inhibition of pyruvate kinase results in switch towards gluconegogenesis
  • Activated in the fed state/insulin by dephosphorylation (phosphatases)
24
Q

Phosphofructokinase-1 (PFK-1)

  • _________ regulator of glycolysis
  • Activity varies according to the energy status of the cell
  • ATP is a substrate and an _________ of PFK-1
  • AMP ________ PFK1 –important in uscle during exercise when AMP levels increase and ATP decreases
A

Phosphofructokinase-1 (PFK-1)

  • Positive regulator of glycolysis
  • Activity varies according to the energy status of the cell
  • ATP is a substrate and an Inhibitor of PFK-1
  • AMP Activates PFK1 –important in muscle during exercise when AMP levels increase and ATP decreases
25
Q

Precursors to Gluconeogenesis?

A

Lactate, Amino Acids (Alanine), and Glycerol

26
Q

Cori Cycle/ Lactic Acid Cycle:

  • Cycle by which lactic acid released by muscle after glycolysis is reconverted in the liver back to glucose and recycled back to the muscle
  • Lactate converted to pyruvate by ________________
  • Pyruvate is then used as a substrate for ______________
A

Cori Cycle/ Lactic Acid Cycle:

  • Cycle by which lactic acid released by muscle after glycolysis is reconverted in the liver back to glucose and recycled back to the muscle
  • Lactate converted to pyruvate by lactate dehydrogenase (LDH)
  • Pyruvate then used as a substrate for gluconeogenesis
27
Q

Alanine converted to pyruvate by ________________

Following deamination, the carbons of amino acids are converted to _______

Amino groups converted to ________

A

Alanine converted to pyruvate by alanine aminotransferase (ALT)

Following deamination, the carbons of amino acids are converted to Glucose

Amino groups converted to Urea

28
Q

__________is the only organ capable of utilizing glycerol produced by the degradation of triglycerides by hormone-sensitive lipase.

A

The Liver is the only organ capable of utilizing glycerol produced by the degradation of triglycerides by hormone-sensitive lipase.

29
Q

__________, which is expressed in the liver, phosphorylates glycerol to glycerol phosphate

A

Glycerol kinase, which is expressed in the liver, phosphorylates glycerol to glycerol phosphate

30
Q

Mutases catalyze the transfer of functional groups within a molecule

A

Mutases catalyze the transfer of functional groups within a molecule

31
Q

______________ –oxidises a substrate by reducing an electron acceptor (NAD+/NADP+/FAD)

A

_Dehydrogenase_ –oxidises a substrate by reducing an electron acceptor (NAD+/NADP+/FAD)

32
Q

__________:

  • Involved in the ________ of pyruvate to oxaloacetate, acetyl-CoA to malonyl-CoA and propionyl-CoA to methylmalonyl-CoA
  • Is a CO2 carrier on the surface of the carboxylase enzyme and is necessary for numerous conversions
  • Excessive ingestion of avidin (which is found in egg whites) has been associated with its deficiency.\
A

Biotin:

  • Involved in the Carboxylation of pyruvate to oxaloacetate, acetyl-CoA to malonyl-CoA and propionyl-CoA to methylmalonyl-CoA
  • Is a CO2 carrier on the surface of the carboxylase enzyme and is necessary for numerous conversions
  • Excessive ingestion of avidin (which is found in egg whites) has been associated with its deficiency.\
33
Q

Pyruvate (3C) converted to oxaloacetate (4C) by __________, a mitochondrial enzyme that requires ATP and ______ as a cofactor

A

Pyruvate (3C) converted to oxaloacetate (4C) by Pyruvate Carboxylase, a mitochondrial enzyme that requires ATP and Biotin as a cofactor

34
Q

__________ –adds CO2 –anabolic/building up -require biotin/ATP

__________ –removing CO2 –catabolic/breaking down

A

Carboxylase –adds CO2 –anabolic/building up -require biotin/ATP

Decarboxylases –removing CO2 –catabolic/breaking down

35
Q

First committed Step of Glycolysis?

A

Step 3: Fructose-6-phosphate is phosphorylated by phosphofructokinase(PFK) to form fructose 1,6 bisphosphate

36
Q

In a fed state, insulin levels rise and induce phosphatases that _____________ (PFK2) that becomes a kinase that converts Fructose-6-Phosphate to Fructose-2,6-BisPhosphate.

Fructose-2,6-BisPhosphate then activates PFK1 which leads to _______ glycolysis and _______ gluconeogenesis

A

In a fed state, insulin levels rise and induce phosphatases that Dephosphorylate (PFK2) which converts Fructose-6-Phosphate to Fructose-2,6-BisPhosphate.

Fructose-2,6-BisPhosphate then activates PFK1 which leads to Increased** glycolysis and **Decreased gluconeogenesis

37
Q

In a fasted state, glucagon levels rise _______ is activated and phosphorylates PFK2 which becomes a phosphatase.

F-2-6-BisPhosphate is then converted to Fructose-6-Phosphate → levels of fructose-2,6-Bisphosphate fall → PFK1 less active→ _______ glycolysis and _________ gluconeogenesis

A

In a fasted state, glucagon levels rise PKA-cAMP is activated and phosphorylates PFK2 which becomes a phosphatase

F-2-6-P is then converted to Fructose-6-Phosphate→levels of fructose-2,6-Bisphosphate fall →PFK1 less active→ Decreased** glycolysis and **Increased gluconeogenesis

38
Q
  • Dephosphorylated PFK2 = ______(Adds or removes phosphate groups?)*
  • Phosphorylated PFK2 = _______(Adds or removes phosphate groups?)*
A

Dephosphorylated PFK2 = Kinase (Adds phosphate groups)

Phosphorylated PFK2 = Phosphatase (Removes phosphate groups)

39
Q

Several tissues use triglyceride breakdown products as intermediates in energy generation and glucose synthesis. Which of the following is a liver-specific enzyme that facilitates such reactions?

A.Acyl CoA synthetase

B.Glycerol kinase

C.Glucose-6-phosphate dehydrogenase

D.Acetyl CoA carboxylase

E.ATP-citrate lyase

A

Several tissues use triglyceride breakdown products as intermediates in energy generation and glucose synthesis. Which of the following is a liver-specific enzyme that facilitates such reactions?

A.Acyl CoA synthetase

B.Glycerol kinase

C.Glucose-6-phosphate dehydrogenase

D.Acetyl CoA carboxylase

E.ATP-citrate lyase

40
Q

A 78-year old female suffers from nausea, anorexia, fatigue and skin rash on her legs. She is mildly demented and is believed to have severe malnutrition. Laboratory findings include lactic acidosis. You suspect that biotin deficiency may contribute to this patient’s symptoms. Which of the following conversions is impaired in those with biotin deficiency?

A.Pyruvate to alanine

B.Pyruvate to oxaloacetate

C.Glucose to ribose-5-phosphate

D.Pyruvate to acetyl-CoA

E.Succinate to oxaloacetate

A

A 78-year old female suffers from nausea, anorexia, fatigue and skin rash on her legs. She is mildly demented and is believed to have severe malnutrition. Laboratory findings include lactic acidosis. You suspect that biotin deficiency may contribute to this patient’s symptoms. Which of the following conversions is impaired in those with biotin deficiency?

A.Pyruvate to alanine

B. Pyruvate to oxaloacetate

C.Glucose to ribose-5-phosphate

D.Pyruvate to acetyl-CoA

E.Succinate to oxaloacetate

41
Q

________________:

  • Enzyme responsible for cleavage of glucose-6-phosphate to glucose
  • This glucose can now be secreted into circulation
  • Enzyme important for both ________ and _______
A

Glucose-6-phosphatase

  • Enzyme responsible for cleavage of glucose-6-phosphate to glucose
  • This glucose can now be secreted into circulation
  • Enzyme important for both gluconeogenesis and glycogenolysis
42
Q

Regulation of Gluconeogenesis in the Liver

A

Sem 1: PATH20000 (22 decks)

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