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Physiology > Overview of Metabolism and Glycolysis > Flashcards

Overview of Metabolism and Glycolysis Flashcards

1
Q

What is metabolism?

A

Metabolism refers a series of chemical reactions in which the product of one reaction is the substrate for the next reaction.

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2
Q

What is catabolism?

A

Catabolism refers to chemical reactions that result in the breakdown of more complex organic molecules into simpler substances, release energy (ATP) that is used to drive chemical reactions.

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3
Q

What is anabolism?

A

Anabolism refers to chemical reactions in which simpler substances are combined to form more complex, new, molecules, usually require energy (ATP).

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4
Q

What are NAD+ and NADP+?

A

Oxidizing agents

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5
Q

What are NADH and NADPH?

A

Reducing agents

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6
Q

What is the end product of glycolysis?

A

Pyruvate

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7
Q

What is the importance of ketone bodies?

A

They are important in starvation as they allow for the operation of neurons

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8
Q

What is glucose stored as in the body?

A

Glycogen

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9
Q

What is fat stored as in the body?

A

Triacylglycerol

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10
Q

What is the main molecule fed into the TCA cycle?

A

Acetyl Coenzyme A (AcCoA)

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11
Q

What is the common cause of lactose intolerance?

A

Lactose intolerance occurs in most adults as a result of decreased lactase enzyme production

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12
Q

In the fed state, what glucose pathways are occurring?

A
  • Glycogenesis
  • Pentose Phosphate Pathway
  • Citric Acid Cycle
  • Glycolysis
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13
Q

What hormone is important in balancing the glucose level in the fed state?

A

Insulin

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14
Q

In the fasting state, what glucose pathways are occurring?

A
  • Glycogenolysis

- Gluconeogenesis

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15
Q

What hormones are important for the glucose balance in the fasting state?

A

Glucagon and Epinephrine

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16
Q

What is the main product of anaerobic respiration?

A

Lactate

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17
Q

What is the main product of aerobic respiration?

A

Pyruvate

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18
Q

What is glycogenesis?

A

Glycogenesis is the formation of glycogen from glucose (hyperglycemia – Insulin increased)

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19
Q

What is glycogenolysis?

A

Glycogenolysis is the break down of glycogen to glucose-1- phosphate and glucose in the liver and in the muscles by the enzyme glycogen phosphorylase (hypoglycemia – glucagon increased)

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20
Q

What is gluconeogenesis?

A

Gluconeogenesis results in the generation of glucose from non- carbohydrate carbon substrates such as pyruvate, lactate, glycerol, and glucogenic amino acids (hypoglycemia – glucagon increased)

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21
Q

What is glycolysis?

A

Glycolysis (means “splitting sugars

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22
Q

What is the sole form of metabolism in RBCs?

A

Glycolysis

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23
Q

What metabolism is found in neurons?

A

Citric Acid Cycle

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24
Q

What metabolism is found in adipose tissue?

A

Glycolysis but no TCA cycle

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25
Q

What glucose receptor is found in liver cells?

A

GLUT 2

26
Q

What glucose receptor is found in skeletal muscle?

A

GLUT 4

27
Q

In the fed state in the liver cell what is the process on glucose?

A

Insulin binds -> Glucose transport into cell via GLUT2 -> Glucokinase converts glucose into G6P

28
Q

In the fasting state in the liver cell what is the process on glucose?

A

Glucagon binds -> G6Pase converts G6P into glucose -> Glucose transport out of cell via GLUT2

29
Q

In the contracting state of a muscle cell what is the process on glucose?

A

Glucose transported into the cell via GLUT4 -> Hexokinase converts it into G6P -> G6P is turned into ATP via glycolysis

30
Q

In the resting state of a muscle cell what is the process on glucose?

A

Glucose transported into the cell via GLUT4 -> Hexokinase converts it into G6P -> G6P is turned into glycogen

31
Q

What are the main 3 enzymes in glycolysis that have irreversible reactions?

A

Hexokinase/Glucokinase
Phosphofructokinase
Pyruvate Kinase

32
Q

What is allosteric regulation and what are the types?

A

Allosteric activation of inhibition of enzyme activity and it can be negative or positive

33
Q

What are the types of enzyme regulation?

A
  • Allosteric
  • Phosphorylation
  • Induction/Suppression of enzyme synthesis
34
Q

What is the first step of glycolysis?

A

Conversion of glucose to G6P via hexokinase/glucokinase

35
Q

What is the importance of the glucose -> G6P reaction?

A

G6P cannot leave the cell and the reaction is irreversible as G6P is impermeable to the membrane as it is too polar

36
Q

Where is hexokinase found?

A

All cells

37
Q

Where is glucokinase found?

A

Liver and pancreas cells

38
Q

What regulates hexokinase?

A

It is allosterically inhibited by its product G6P.

39
Q

Where is glucokinase in its active form and inactive form?

A

Active: Cytosol
Inactive: Nucleus

40
Q

What will promote glucokinase activity?

A

Glucose does so by promoting glucokinase translocation into the cytosol

41
Q

What will inhibit glucokinase activity?

A

Fructose-6-P will decrease glucokinase activity by promoting translocation into the nucleus

42
Q

What will increase glucokinase synthesis?

A

Insulin

43
Q

What has the higher glucose affinity, hexokinase or glucokinase?

A

Hexokinase

44
Q

What converts Fructose-6-Phosphate to Fructose-2,6-Bisphosphate?

A

PFK-2

45
Q

What converts Fructose-6-Phosphate to Fructose-1,6-Bisphosphate?

A

PFK-1

46
Q

What regulates the activity of PFK-1?

A

The activity of PFK-1 is regulated by Fructose-2,6-Bisphosphate, the product of PFK-2

47
Q

In the liver what is the effect of E and glucagon on PFK-2 and hepatic glycolysis?

A

Inhibitory

48
Q

How does glucagon inhibit PFK-2?

A

Glucagon stimulates the formation of cAMP. cAMP activates protein kinase A. Protein kinase A phosphorylates PFK-2 and inhibits the production of fructose 2,6-bisP.

49
Q

What is the effect of epinephrine and glucagon on hepatic glycolysis?

A

Inhibits

50
Q

What is the effect of epinephrine and glucagon on muscular and cardiac glycolysis?

A

Stimulates. Epinephrine (but not glucagon) activates heart and skeletal muscle PFK-2 by inhibiting the phosphatase activity

51
Q

What are some of the effects of glucagon and epinephrine?

A
  • Inhibits PFK-2 which leads to decreased fructose-2,6-bisphosphate and decreases the activity of PFK-1
  • Inhibits pyruvate kinase
52
Q

How is NAD+ regenerated?

A
  • Lactate dehydrogenase (Cytosolic reaction)
  • Malate-aspartate shuttle (Cytosol and mitochondria)
  • Glycerol-phosphate shuttle (Cytosol and mitochondria)
53
Q

What is the function of lactate dehydrogenase?

A

LDH regulates pyruvate concentration by converting pyruvate to lactate and vice versa

54
Q

What is the reaction of LDH in skeletal muscle?

A

In skeletal muscle, the LDH5 M4 ISOZYME prefers to catalyze the conversion of pyruvate to lactate; this allows for high bursts of energy.

55
Q

What is the reaction of LDH in the cardiac muscle?

A

In heart muscle, the H4 ISOZYME prefers to catalyze the conversion of lactate to pyruvate; this allows for a sustained production of energy.

56
Q

What is the function of pyruvate dehydrogenase?

A

Pyruvate dehydrogenase is a enzyme complex that converts pyruvate and coenzyme A to acetyl-CoA

57
Q

How is pyruvate dehydrogenase regulated?

A

NADH and Ac-CoA, end-products of PDH reaction promote the phosphorylation and inhibition of this enzyme.

58
Q

What do anaerobic conditions favor?

A

Anaerobic conditions favor the formation of lactate

59
Q

What is the problem in Lactate Dehydrogenase Deficiency?

A

When lactate dehydrogenase levels are insufficient, the level of NAD+ becomes limiting during exercise and flux through the glyceraldehyde-3-P dehydrogenase reaction is inhibited.

60
Q

What is the problem in galactosemia?

A

Deficiency in:
- galactokinase
OR
- galactose 1-phosphate uridyltransferase

61
Q

What enzyme is implicated in fructose intolerance?

A

Aldolase B

Physiology (81 decks)

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