Page 118 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

74 SECTION II BIOCHEmISTRY ``BIOCHEMISTRY—METABOlISM BIOCHEmISTRY ``BIOCHEMISTRY—METABOlISM

Summary of pathways

Galactokinase (mild galactosemia) Galactose metabolism
Galactose-1-phosphate Galactose B Requires biotin cofactor
uridyltransferase T Requires thiamine cofactor (TPP)
(severe galactosemia) Glycolysis #
Hexokinase/glucokinase Glycogen Galactose-1-phosphate Glucose Irreversible, important point of regulation
Glucose-6-phosphatase HMP shunt
(von Gierke disease)
UDP-glucose Glucose-1-phosphate Glucose-6-phosphate 6-phosphogluconolactone
Glucose-6-phosphate
dehydrogenase Glycogenesis / glycogenolysis
Transketolase Fructose-6-phosphate T Ribulose-5-phosphate
Phosphofructokinase-1 Gluconeogenesis
Fructose-1,6-bisphosphatase Fructose-1,6-bisphosphate Fructose metabolism
Fructokinase (essential fructosuria)
Aldolase B (fructose intolerance) Glyceraldehyde-3-P DHAP Fructose-1-phosphate Fructose
Aldolase B (liver), A (muscle)
Triose phosphate isomerase 1,3-bisphosphoglycerate Glyceraldehyde
Pyruvate kinase
3-phosphoglycerate Glycerol Lipid metabolism
Pyruvate dehydrogenase
Pyruvate carboxylase
2-phosphoglycerate Triglycerides
PEP carboxykinase
Citrate synthase
Phosphoenolpyruvate (PEP) Fatty acids
Isocitrate dehydrogenase
α-ketoglutarate dehydrogenase Alanine Pyruvate Lactate Cholesterol
Malonyl-CoA
Carbamoyl phosphate synthetase I T
B
Ornithine transcarbamylase B Acetyl-CoA Mevalonate
Propionyl-CoA carboxylase Acetoacetyl-CoA HMG-CoA
HMG-CoA reductase
Citrate Acetoacetate
Oxaloacetate
Aspartate
NH + CO 2
3
Citrulline Isocitrate β-hydroxybutyrate
Ketogenesis
Carbamoyl phosphate Argininosuccinate
Malate TCA cycle
Ornithine Odd-chain fatty acids,
Urea cycle α-ketoglutarate isoleucine, valine,
Fumarate methionine, threonine
T
Arginine
Urea Succinate Succinyl-CoA B 12 Methylmalonyl-CoA B Propionyl-CoA
H O Protein metabolism
2

ATP production Aerobic metabolism of one glucose molecule Arsenic causes glycolysis to produce zero net
produces 32 net ATP via malate-aspartate ATP.
shuttle (heart and liver), 30 net ATP via
glycerol-3-phosphate shuttle (muscle).
Anaerobic glycolysis produces only 2 net ATP
per glucose molecule.
ATP hydrolysis can be coupled to energetically
unfavorable reactions.

FAS1_2019_01-Biochem.indd 74 11/7/19 3:16 PM