Metabolism Flashcards
What is anabolism?
Synthesis of simple products to complex products
What is catabolism?
Breakdown of complex products to simpler products
What are metabolism pathways controlled by?
Enzymes (protein catalysts)
What are cofactors (coenzymes)?
-Additional chemistry to help catalyse a reaction
-Can be permanently attached to the enzyme as a prosthetic group
-Can come on and off when required using reversible binding
What pathways does carbohydrate catabolism involve?
-Glycolysis
-Krebs cycle
-Electron transport chain
What is glycolsis?
The breakdown of the 6 carbon glucose to 2x 3 carbon pyruvate
Where does glycolysis occur?
Cytoplasm
What type of reaction is glycolysis?
Anaerobic (can occur without oxygen)
What is used to activate glycolysis?
2 ATP molecules are required to activate the glucose
What occurs as the glucose splits?
-Energy from the glucose molecule is stripped out and stored in an NADH hydrogen carrier
-Energy is in the form of ATP
What is the net produce of glycolysis?
-4 ATP, 2 net gain
-2 pyruvate
-2 NADH
How does the splitting of glucose occur?
-Adenosine triphosphate (ATP) donates a phosphate group to glucose mol.
-Another phosphate group is then added to the fructose molecule (5C)
-Breaks down to 2x glyceraldehyde 3 phosphate (3C)
-Energy is removed and produces 2 pyruvate
What enzyme catalyses the addition of a phosphate group to glucose?
Hexokinase
What enzyme catalyses the addition of a phosphate group to fructose?
Phosphofructokinase
What enzyme catalyses the production of pyruvate?
pyruvate kinase
What is NAD+?
-Nicotinamide adenine dinucleotide
-A hydrogen ion carrier
What is FAD?
-Flavine adenine dinucleotide
-hydrogen ion carrier
What is ATP?
-Adenosine Triphosphate
-Energy is stored within the bonds between phosphates
What is the first fate of pyruvate?
-Liver can convert pyruvate to glucose via gluconeogenesis
-Occurs in areas where there is a high demand for glucose, e.g. brain
What is the second fate of pyruvate?
-Absorption of ammonia into the pyruvate
-Ammonia is toxic so fuses with pyruvate to form amino acid alanine
What is the fate of pyruvate when there is an absence of oxygen?
-Anaerobic respiration
-Pyruvate converts to ethanol
-Occurs in yeast cells
-Pyruvate converts to lactic acid in animals
What is the fate of pyruvate in the presence of oxygen?
-Aerobic respiration
-Crosses into mitochondria
-Converts to acetyl coA and enters kreb cycle
What is coenzyme A?
-Nucleotide with adenine base
-Carrier of 2 carbon units
Where does the krebs cycle occur?
Mitochondria
What occurs to acetyl CoA in the krebs cycle?
-The 2C molecule is fed in and the 2 carbons are oxidised forming CO2
What is released when acetyl CoA is oxidised in the krebs cycle?
The energy comes out as hydrogen ions and is picked up by NADH and FADH2 carriers
What happens to the 2 carbons from the acetyl CoA in the krebs cycle?
Combine with the 4 carbon oxaloacetate and forms a 6 carbon molecule
What happens to the 6 carbon molecule in the krebs cycle?
-A carbon is lost forming a 5 carbon molecule
-Comes out as CO2
What happens to the 5 carbon molecule in the krebs cycle?
-A carbon is lost forming a 4 carbon molecule
-Comes out as CO2
What is released throughout the krebs cycle?
-Energy is released as hydrogen
-Picked up by NADH and FADH2 carriers
-Used in electron transport chain
What occurs in the electron transport chain?
-NADH and FADH2 hydrogen carriers are fed in
-Oxygen combines with hydrogen
-Produces water and ATP
Where does the electron transport chain occur?
Mitochondria
What is transported through the proteins of the ETC?
Electrons from the bonds between NAD/FAD and the hydrogen ions
What is the final electron acceptor in the ETC?
Oxygen
How is water formed in the ETC?
Electrons combine with hydrogen and oxygen
How is the chemical gradient created in the ETC?
-Energy is stripped from the electrons as they pass through the chain
-Proteins can then pump hydrogen ions down the gradient
How is ATP synthesised in the ETC?
-ATP synthase uses energy from the H+ gradient
-Puts it in the ATP storage molecule
