General metabolism Flashcards
Reaction pathway locations
Reactions occurring in the cytoplasm
Glycolysis, glycogenolysis, fatty acid synthesis, PPP, part of the urea cycle.
Reaction pathway locations
Reactions occurring in the mitochondria
Citric acid cycle, oxidative phosphorylation, β-oxidation, part of the urea cycle, pyruvate oxidation (mitochondrial matrix)
The highest energy pathways occur in the mitochondria; everything else in the cytoplasm. Urea cycle is unique in that it spans both.
Metabolic organs
Liver
Primary site of glucose regulation through gluconeogenesis and glycogen formation/breakdown, in response to insulin and glucagon.
Metabolic organs
Adipocytes
These store lipids which are released in response to catecholamines.
Metabolic organs
Thyroid
Help regulate the basal metabolic rate.
Metabolic organs
Pancreas
The site of insulin and glucagon production.
Insulin versus glucagon
Organic phosphates
Structure
ATP consists of an adenosine connected to three phosphate groups;
GTP consists of guanosine connected to three phosphate groups.
The phosphates are labeled as α-, β-, and γ-phosphates, starting from the nucleotide.
Organic phosphates
carbon-containing compounds with phosphate groups, most commonly ATP and GTP.
Organic phosphates
ATP hydrolysis
The endmost phosphate (γ-phosphate) bond is broken in an ATP hydrolysis reaction, releasing 30 kJ/mol of energy.
Organic phosphates
Coupling
ATP hydrolysis is a favorable reaction with -ΔG.
Many reactions will couple to the ATP hydrolysis reaction to become more favorable.
Organic phosphates
Phosphorylation
The process of adding a phosphate group to a compound, usually catalyzed by a kinase.
Organic phosphates
Flavoproteins
A class of electron carrier molecules that are derived from riboflavin and contain FAD.
Metabolic regulation
Regulation of appetite
Ghrelin and orexin increase appetite while leptin decreases appetite.
Metabolic regulation
Thyroid hormones (T3 and T4)
Released by the thyroid in response to TSH.
Increases basal metabolic rate.
Urea cycle
Amino acid metabolism results in the toxic product ammonia (NH3).
Through the urea cycle, this is converted to urea and excreted through the kidneys.
Urea cycle
Location
A series of reactions that occurs in both the cytoplasm and mitochondria of the cell.
Occurs in the liver.
Urea cycle
Link to other pathways
The urea cycle produces oxaloacetate and fumarate which are part of the citric acid cycle as well.
