Glycolysis Flashcards
What is metabolism?
All the chemical reactions that maintain the living state of cells and organisms
What is anabolism?
The building up of molecules to form the building blocks of life. Requires energy
What is catabolism?
The breakdown of molecules to obtain the anabolic building blocks of life and substrates for energy. It yields energy
What is the mechanism in anabolism?
Oxidised precursors are reduced to form reduced biosynthesic products. It is endergonic and reductive
What is the mechanism present in catabolism?
Reduced fuel is oxidised to form oxidised products. Exergonic and oxidative
What is oxidative phosphorylation?
The addition of an electron to oxygen to form water, creating energy
What can glucose be in the form of?
In plants: Starch or cellulose
In animals: Glycogen
What cell types require ATP as an energy source?
Erythrocytes Retina Renal medulla Brain Cancer cells
What are the fates of glucose?
Glycogen, starch, sucrose, lipids
Pyruvate via oxidation through aerobic glycolysis
Lactate via fermentation in anaerobic glycolysis
Ribose-5-phosphate via oxidation through the pentose phosphate pathway
How is glucose transported into cells?
Via Na+/glucse symporters
Via passive facilitated diffusion glucose transporters:
GLUT 1 = Brain - low Km
GLUT 2 = Liver, beta cells - High Km, insulin dependent
GLUT 3 = Brain - low Km
GLUT 4 = Muscle and adipose tissue - insulin dependent
GLUT 5 = Gut - fructose transport
What is GLUT 1 used for?
The binding of glucose on the outside of GLUT 1 triggers a conformational change causing the binding site to change and face inwards. Glucose is then released on the inside of the cells which results in a conformational change regenerating the binding site on the outside
In simple terms, what is glycolysis?
The initial pathway for the conversion of glucose to pyruvate
Glucose + 2 ADP + Pi + 2NAD+ = 2 pyruvate, 2 ATP, 2 H20, 2 NADH, 2H+
What is the pathway for glycolysis?
Glucose - fructose-1,6-biphosphate - 2 triose phosphates - 2 pyruvate
What occurs during stage one of glycolysis?
Glucose is trapped and destabilised - glucose to fructose-1,6-biphosphate
What occurs during stage 2 of glycolysis?
Two interconvertible 2-carbon molecules are formed
What occurs during stage 3?
1 pyruvate molecules is formed and 2 ATP are formed. Stage 3 occurs twice and therefore at the end of glycolysis, there is 2 pyruvate molecules and 4 ATP molecules
What are the three control points in glycolysis?
- Hexokinase controls substrate entry
- Phosphofructokinase controls the rate of flow
- Pyruvate kinase controls the product exit
What is the reaction for hexokinase?
Glucose + ATP = glucose-6-phosphate + ADP + H+
What is the reaction for phosphfructokinase?
Fructose-6-phosphate + ATP = fructose-1.6-biphosphate + ADP + H+
What is the reaction for ppyruvate kinase?
Phosphoenolypyruvate + ADP + H+ = pyruvate + ATP
What does phosphfructokinase (PFK) do?
Key enzyme for controlling the rate of substrate movement along the glycolytic pathway
What activates PFK?
AMP and fructose-2,6-biphosphate. These will be used if energy is needed
What inhibits PFK?
ATP - will slow glycolysis if ATP is abundant
Citrate - Will slow downstream pyruvate entry to TCA cycle
H+ - slows glycolysis if too much lactic acid is being produced
What is the ATP/AMP ratio called?
The energy charge
