Integrating Metabolism Flashcards
Define “energy coupling”
Energy produced by one action or system being used to drive another reaction.
What is an exergonic reaction?
A reaction which releases energy (negative ∆G).
What is an endergonic reaction?
A reaction which absorbs energy (positive ∆G).
What is anabolism?
A reductive reaction.
Energy requiring reaction.
Produce larger complexes from smaller ones.
Uses the energy from catabolism.
What is catabolism?
An oxidative reaction.
Energy releasing.
Breakdown of complex molecules to form simpler ones.
What mechanism converts glycogen to glucose-6-phosphate?
Glycogenolysis (via glycogen phosphorylase).
Where in the body is glucose-6-phosphate (G6P) primarily used?
Muscles:
Important source of energy during high intensity, shorter exercise.
Liver:
G6P converts to glucose and enters bloodstream.
What mechanism converts Glucose-1-phosphate (G1P) to glycogen?
Glycogenesis (via glycogen synthase).
Define gluconeogenesis?
The synthesis of glucose from non-carbohydrates (i.e. lactate, glycerol, AAs).
Define the Cori cycle.
Lactate produced by muscular glycolysis.
Transported to liver.
Converted to glucose.
Returns to muscles for re-use.
What is the term used to describe the sacrifice of muscle protein to produce glucose for the brain?
Starvation
Describe what happens during fatty acid oxidation in mitochondria?
Short and medium chain fatty acids enter directly.
Long chains shuttle in using carnitine carriers.
Fatty acids broken down to generate Acetyl-CoA molecules.
Beta oxidation occurs.
Describe the beta oxidation of fatty acids?
The breaking down of fatty acids to acetyl-coa to either:
Feed into the TCA cycle
OR
Generate ketone bodies.
Each turn generates:
Acetyl-CoA.
A reducing equivalent for electron transport chain.
How is Acetyl-CoA used post-beta oxidation?
Acetyl CoA either generates ketone bodies or feeds into tricarboxylic acid cycle.
How is your body supplied with essential and non-essential amino acids?
Essential - from diet.
Non-essential - derived from transamination.
What happens in a scenario where there is excess amino acids?
The excess are catabolised to urea via deamination.
The deaminated carbon skeletons are oxidised via the tricarboxylic acid cycle.
Where does catabolism of amino acids mainly occur?
In the liver.
What occurs during catabolism of amino acids?
Amino group is removed from amino acids (enters urea cycle for excretion).
Carbon skeleton either: Oxidised to CO2 + H20.
Used for gluconeogenesis.
Used for ketogenesis.
How is nitrogen metabolised?
Amino nitrogen enters urea cycle for excretion.
What is the meaning of the term “amphibolic”?
A cycle which serves as both catatonic and anabolic.
What is anaplerosis?
The replenishment of tricarboxylic acid cycle (TCAC) intermediates.
What are tricarboxylic acid intermediates? What are their uses?
Metabolites which are not used up in the oxidation of acetyl CoA.
Are used in the synthesis of pyrimidines, porphyrins, lipids etc.
In anaplerosis, What does pyruvate carboxylase yield?
Oxaloacetate.
In anaplerosis, what does glutamate dehydrogenase yield?
Oxaloacetate.
In anaplerosis, what does beta-oxidation of odd-chain fatty acids yield?
Succinyl CoA.
Briefly describe the meaning of fed -> fasted.
Contribution of dietary glucose is replaced firstly at the expense of liver glycogen.
Next is the expense of muscle protein by gluconeogenesis.
Key roles in:
Insulin.
Glucagon.
Cortisol.
How does your body deal with carbohydrates in a “fed state” of metabolism?
Processes the carbohydrates through:
Glycolysis.
Glycogenesis.
Lipogenesis.
How does your body utilise free fatty acids in a “fed state” of metabolism?
Triglycerides are synthesised from free fatty acids (FFA).
For storage in adipose tissue
How does your body react to a “fed state” of metabolism in terms of amino acids and proteins?
Amino acid synthesis occurs.
Protein metabolism occurs.
What is the key signal for a “fed” metabolic state?
Insulin.
In a “fasted state” of metabolism, which mechanisms supply your body with glucose?
Glycogenolysis and gluconeogenesis.
During a “fasted state” of metabolism, how is adipose tissue utilised?
Lipolysis of adipose tissue releases free fatty acids and glycerol.
Glycerol converted to glucose via gluconeogenesis.
Why does the body begin oxidating free fatty acids and ketones in the fasted state? How does this affect the body?
Oxidation creates a supply of energy, sparing glucose.
Causes ketosis.
How does the body utilise proteins and amino acids when in a “fasted state”?
Protein catabolism occurs.
Amino acids converted to glucose through gluconeogenesis.
How are pancreatic hormones affected by a “fasted state”?
Glucagon active.
Insulin suppressed.
