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BIOCHEMISTRY > ME03 - GLYCOLYSIS > Flashcards

ME03 - GLYCOLYSIS Flashcards

1
Q

Major pathway for glucose metabolism

A

Glycolysis

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2
Q

Substrate and Product

A

Substrate: Glucose
Product: Pyruvate

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3
Q

Overall Reaction

A

Glucose + 2ADP + 2P&raquo_space; 2Lactate or Pyruvate + 2 ATP + 2 H2O

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4
Q

Where does Glycolysis occur?

A

Cytoplasm of all cells

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5
Q

GLUT TRANSPORTERS

A

1 - Erythrocytes, BBB | Uptake of glucose
2- Liver, Pancreatic B Cells | Uptake of glucose
3- BRAIN, Neurons, Placenta | Uptake of glucose
4- Heart and Skeletal Muscle, Adipose Tissue | “Insulin-timulated uptake of Glucose”
5 - Small Intestine | Absorption of Fructose at luminal side of Small Intestine

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6
Q

Types of Glycolysis

A

Anaerobic - Cells without mitochondria (RBC, White Muscle
Final Product: Lactate | Lactic Acidosis
Aerobic - Cells with mitochondria and supply of O2
Final Product: Pyruvate

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7
Q

2 Stages of Glycolysis

A
  1. Energy Investment Phase - 2 ATPs Phosphorylation

2. Energy Generation Phase - 2 molecules of ATP are formed by substrate level phosphorylation (produce ATP)

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8
Q

Purpose of PO4

A

Trap Glucose inside the cells

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9
Q

Irreversible steps in Gycolysis

A
  1. Phosphorylation of Glucose
  2. Phosphorylation of fructose 6-phosphate (RATE LIMITING STEP)
  3. Formation of pyruvate
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10
Q
  1. Glucose&raquo_space; Glucose 6P
A

Hexokinase vs Glucokinase

Hexokinase - in most tissues | Phosphorylate Glu, Fru, Gal | Inhibited by Glucose 6P | Low Km, Low Vmax | High affinity for glucose - UTILIZE ENERGY FIRST

Glucokinase - in liver parenchymal cells, islets of pancreatic cells | Phosphorylate glucose alone | Inhibited by Fructose 6P | High Km, High Vmax | Low affinity for Glucose
- HELPS STORE EXCESS ENERGY

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11
Q
  1. Fructose 6P&raquo_space; Fructose 1,6BP
A

Enzyme: Phosphofructokinase

IRREVERSIBLE AND RATE-LIMITING STEP OF GLYCOLYSIS

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12
Q

Difference of PFK1 and PFK2

A

PFK1 - converts fructose 6P to fructose 1,6BP | Inhibited by ATP and citrate | Activated by Fructose 2,6BP (Most potent, via allosteric activation) and AMP

PFK2 - coverts fructose 6P to fructose 2,6BP | Inhibited by DEC insulin, INC glucagon (Starvation) | Activated by (Well-fed state) INC insulin DEC glucagon

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13
Q
  1. PEP&raquo_space; Pyruvate
A

Substrate-level phosphorylation to yield 1 ATP per molecule of phosphoenolpyruvate
Enzyme: Pyruvate kinase
Activated by: Fructose 1,6BP
Inhibited by Phosphorylation, Which occurs when INC glucagon, INC cAMP

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14
Q

Steps involved in production of ATP

A

1,3BP&raquo_space; 3 Phosphoglycerate (Phosphoglycerate kinase)

PEP&raquo_space; Pyruvate (Pyruvate kinase)

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15
Q

Most common defect in Glycolysis

A

PK Deficiency
Manifest Chronic Hemolytic Anemia
Aldolase A deficiency can also cause Hemolytic Anemia

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16
Q

Px has low exercise capacity, particularly on HIGH CHO diets

A

Muscle Phosphofructokinase Deficiency

17
Q

Role of NADH in Glycolysis

A

Oxidation of Glyceraldehyde 3 PO4&raquo_space; 1,3BPG

Enzyme: Glyceraldehyde PO4 dehydrogenase

18
Q

Possible fates of NADH

A

Enter malate-aspartate or G3P shuttle and be converted to ATP.
Can also convert pyruvate to Lactate

19
Q

In AEROBIC GLYCOLYSIS, NADH is converted to ATP and trnasported using 2 shuttles

A

Malate-Aspartate Shuttle&raquo_space; Yields 3 ATPs each (liver, kidney and heart)

Glycerol Phosphate Shuttle&raquo_space; Yields 2 ATPs each (Skeletal muscle, brain)

20
Q

In ANAEROBIC GLYCOLYSIS, Pyruvate is converted to Lactate by the action of

A

Lactate dehydrogenase

21
Q

Possible fates of Pyruvate

A

RBCs, Lens, and Corneas of the Eye, Kidney Medulla, WBC, Testes

22
Q

Synthesis of 2,3 BPG

A

Enzyme: Bisphosphoglycerate mutase
Fx: Binds to Hgb and cause shift to the R of the HgbO2 dissociation curve
Example: Chronic Hypoxia&raquo_space; Reactive Polycythemia&raquo_space; INC BPG mutase,&raquo_space; INC 2,3 BPG&raquo_space; SHIFT TO THE R

23
Q

Pyruvate&raquo_space; Acetyl CoA

A

Enzyme: Pyruvate Dehydrogenase complex with co-enzymes:

  1. Thiamine pyrophosphate
  2. FAD
  3. NAD+
  4. Coenzyme A (contains pantothenic acid)
  5. Lipoic acid
24
Q

Pyruvate and Acetyl CoA is activated and inhibited by

A

Activated by: NAD+ CoA and pyruvate

Inhibited by: ATP, Acetyl CoA, NADH

25
Q

Most common biochemical cause of congenital lactic acidoses, Brain is deprived of Acetyl CoA

A

Pyruvate Dehydrogenase Deficiency

Treatment: ketogenic diet

26
Q

Inactivates PDH by binding to lipoic acid so it competes with inorganic phosphate as a substrate for glyceraldehyde 3P Dehydrogenase

A

Arsenic Poisoning

27
Q

Prone to thalamine - deficiency and may develop potentially fatal pyruvate and lactic acidosis

A

Chronic alcoholism

28
Q

ATP Yield in Aerobic and Anaerobic

A

ATPs in Substrate-Level Phosphorylation : 4 both
ATPs from NADH (aerobic 4-6) (anaerobic 0)
ATPs consumed (aerobic -2) (anaerobic -2)
Total (Aerobic - 6 or 8) (Anaerobic 2)

BIOCHEMISTRY (25 decks)

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