Metabolism Flashcards
How is energy stored in ATP
Through the phosphoanhydride bonds. When the bonds are broken the energy is released.
If more energy is needed to be released we break the phosphoanhydride bonds between the beta and alpha bonds releasing ppi ( pyrophosphate).
Substrate- level phosphorylation
The transfer of a phosphate from a molecule to ATP.
How is energy stored in NADH and FADH2?
Through their reduction potentials
Secondary v. Primary active transport
Secondary transport is when the energy released from a molecule moving down it’s concentration gradient powers the movement of molecule against their concentration gradients.
Primary active transport is when the hydrolysis of ATP moves molecules against their concentration gradients.
Catabolism v. Anabolism
Catabolism is the breakdown of molecules whereas anabolism is the creation of larger molecules from metabolites.
What happens when the free energy of a reaction is large?
Not all the energy is captured and therefore some of it is wasted and the reaction is irreversible.
Futile cycle
Unregulated recycling of substrates between catabolic and anabolic reactions .
Purpose of glucose in the cell
Primary energy source for the cell
it’s skeleton can be used to form other molecules
it’s byproducts can be used to protect cell against oxidative damage to build other molecules.
Net products of glycolysis
for every 1 molecule of glucose you get 2 ATP, 2 NADH, and 2 pyruvate
Energy- investment phase v. Energy- payoff phase of glycolysis
Energy- investment phase is the first five steps of glycolysis and uses ATP.
The energy- payoff phase is the last steps of glycolysis and is where the lost is recuperated and we gain net energy products.
Incorporation of mannose into the glycolytic cycle
Mannose is phosphorylated by hexokinase into mannose-6-phosphate.
Mannose-6- phosphate is converted to fructose-6-phosphate by phosphomannose isomerase.
Incorporation of fructose into the glycolytic cycle
Fructose is converted to fructose-6-phosphate by hexokinase.
In the liver it’s converted to fructose-1-phosphate by fructokinase. Fructose-1-phosphate is then converted to DHAP and glyceraldehyde via aldolase. Glycerol is converted to glyceraldehyde-3- phosphate by triose. These then go on to glycolysis.
Incorporation of galactose into the glycolytic cycle
Galactokinase converts galactose to galactose-1-phosphate. GALT transfers UDP from UDP- glucose to galactose creating UDP- galactose and glucose-1-phosphate.
The enzyme phosphoglucomutase converts the glucose-1-phosphate to glucose-6- phosphate.
Process of gluconeogenesis and the enzymes involved
Primarily happens in the liver and serves to make glucose via the reverse of glycolysis, using enzymes to bypass the irreversible steps.
pyruvate carboxylase converts pyruvate to oxaloacetate. Phosphenolpyruvate carboxykinase (PEPCK) converts oxaloacetate into phosphenolpyruvate.
fructose-1,6-bisphosphatase converts fructose-1,6- bisphosphate to fructose-6- phosphate.
glucose-6-phosphatase converts glucose-6-phosphate to phosphate.
How can alanine be ushered into gluconeogenesis?
By converting alanine to pyruvate via deamination.
How does lactic acid fermentation and gluconeogenesis are linked?
During lactic acid fermentation pyruvate is converted to lactate but in the liver it’s reversed so pyruvate can enter gluconeogenesis.
How can catabolism of triacylglycerol participate in gluconeogenesis?
Glycerol is produced by the breakdown of triacylglycerol which is phosphorylated to glycerol-3-phosphate. This is then oxidized to DHAP which can enter glycolysis directly.
Purpose of the Cori cycle?
It’s a method that allows humans to thrive in diverse environments.
In systems in hypoxic environments or that lack mitochondria lactic acid fermentation creates lactate which is then exported to the blood and to the liver where it’s converted back to pyruvate where it undergoes gluconeogenesis. The glucose is released by the liver into the bloodstream where it’s taken up by muscles that need it.
