39. Biosynthetic Pathways Flashcards
What are the general features of anabolic pathways?
Use chemical energy
Form precursors
Form complex molecules from simple precursors
Link these complex molecules together
What are the substrates in gluconeogenesis?
Lactate
Glycerol
Amino acids
What converts lactate to pyruvate?
Lactate dehydrogenase
What is glycerol converted to?
Glycerol phosphate
DHAP
Glyceraldehyde-3-phosphate
What are amino acids converted to?
Oxaloacetate
PEP
What converts pyruvate to oxaloacetate?
Pyruvate carboxylase
What activates pyruvate carboxylase?
acetyl coA
What converts oxaloacetate to PEP?
PEP carboxykinase
What dephosphorylates fructose-6-phosphate?
fructose-1,6-phosphatase
What is gluconeogenesis inhibited by?
AMP
Fructose-2,6-bisphosphate
What is gluconeogenesis increased by?
Glucagon
What dephosphorylates glucose-6-phosphate?
Glucose-6-phosphatase
Phosphate is released into the endoplasmic reticulum
What does glucose-6-phosphate translocase do?
Transports G6P to the endoplasmic reticulum
What is the pentose phosphate pathway?
Alternative branch off glycolysis to produce the sugars that make up DNA and RNA
What happens in the oxidative stage of the pentose phosphate pathway
Glucose-6-phosphate is oxidised to lactone
NAD+ reduced to NADPH
Glucose-6-phosphate and water used to make 6-phosphogluconate
Carbon removed and CO2 released
Electrons used to make NADPH
New molecule is ribulose-5-phosphate
What enzymes catalyse the oxidative phase of the pentose phosphate pathway?
Glucose 6-phosphate dehydrogenase
6-phosphogluconolactone hydrolase
What happens in the cyclic phase of the pentose phosphate pathway?
Ribulose-5-phosphate is converted to another 5-carbon sugar
2 added together to make one 10-carbon molecule
Can make a 3C and 6C molecule for glycolysis
Or 4C precursor for amino acids
What are the anabolic uses of NADPH?
Synthesis of : cholesterol steroid hormones fatty acids sphingomyelin phospholipids
Which amino acids are ketogenic?
Alanine
Aspartate
Glutamate
What do ketogenic amino acids produce when deaminated?
a-keto acids
How are asparagine and glutamine produced?
Amidation
How is proline produced?
Cyclization of glutamate
How is tyrosine produced?
Hydroxylation of phenylalanine
Where are purines gotten from?
Made de novo
Salvaged
What is needed to produce pyramidines?
Glutamine
CO2
ATP
Folic acid
What is needed to make purines?
Pentose-5-phosphate
Phosphate
What is purine synthesis inhibited by?
Purine nucleotides
Where are pyrimidines gotten from?
Made de novo
What are purines degraded into?
Xanthine Uric acid (excreted)
