CHEM 8020: Pentose Phosphate Pathway and Insulin/Glucagon

These flashcards review important vocabulary and concepts related to the Pentose Phosphate Pathway and insulin/glucagon signaling.

Pentose Phosphate Pathway (PPP)

A metabolic pathway that produces NADPH and ribose-5-phosphate for anabolic reactions.

Starting material for the PPP

Glucose-6-phosphate (G-6-P).

Phases of the PPP

The pathway has two phases: the oxidative phase (irreversible) and the non-oxidative phase (reversible).

Rate-limiting enzyme in PPP

Glucose-6-phosphate dehydrogenase (G-6-P Dehydrogenase).

Major byproduct of the first phase of PPP

NADPH, which is essential for lipid synthesis.

Regulation of G-6-P Dehydrogenase

It is allosterically activated by NADP+ and inhibited by NADPH.

End product of the first phase that enters the second phase of PPP

Ribulose-5-phosphate.

Major products formed in the second phase of PPP

Ribose-5-phosphate and various sugars.

Major functions of ribose-5-phosphate

It is used in nucleotide synthesis.

Major functions of NADPH

It serves as a reducing agent in biosynthetic reactions and helps in fatty acid and cholesterol synthesis.

G-6-P Dehydrogenase deficiency

It compromises red blood cells, leading to symptoms like hemolytic anemia.

Fasting hormone

Glucagon.

Fed hormone

Insulin.

Hormone that activates a tyrosine kinase

Insulin.

Hormone that activates a G-coupled protein

Glucagon.

Hormone that stimulates the phosphorylation of regulated enzymes

Glucagon.

Hormone that stimulates de-phosphorylation of regulated enzymes

Insulin.

Hormone stimulated by stress hormones

Glucagon.

Hormone inhibited by stress hormones

Insulin.

Hormone that turns on glycolysis

Insulin.

Hormone that turns on gluconeogenesis

Glucagon.

Hormone that turns off glycogenesis

Glucagon.

Hormone that turns off glycogenolysis

Insulin.

Hormone that turns on lipogenesis and proteogenesis

Insulin.

Hormone that turns on lipolysis and proteolysis

Glucagon.

Anabolic hormone

Insulin.

Catabolic hormone

Glucagon.

Pentose Phosphate Pathway (PPP)

A metabolic pathway that produces NADPH and ribose-5-phosphate for anabolic reactions.

Starting material for the PPP

Glucose-6-phosphate (G-6-P).

Phases of the PPP

The pathway has two phases: the oxidative phase (irreversible) and the non-oxidative phase (reversible).

Rate-limiting enzyme in PPP

Glucose-6-phosphate dehydrogenase (G-6-P Dehydrogenase).

Major byproduct of the first phase of PPP

NADPH, which is essential for lipid synthesis.

Regulation of G-6-P Dehydrogenase

It is allosterically activated by NADP+ and inhibited by NADPH.

End product of the first phase that enters the second phase of PPP

Ribulose-5-phosphate.

Major products formed in the second phase of PPP

Ribose-5-phosphate and various sugars.

Major functions of ribose-5-phosphate

It is used in nucleotide synthesis.

Major functions of NADPH

It serves as a reducing agent in biosynthetic reactions and helps in fatty acid and cholesterol synthesis.

G-6-P Dehydrogenase deficiency

It compromises red blood cells, leading to symptoms like hemolytic anemia.

How does NADPH protect against oxidative stress?

NADPH reduces oxidized glutathione via glutathione reductase, which then converts reactive oxygen species (ROS) into harmless compounds. This is particularly crucial in red blood cells.

What is the fate of the "various sugars" produced in the non-oxidative phase of the PPP?

These sugars (e.g., fructose-6-phosphate, glyceraldehyde-3-phosphate) can be re-routed to glycolysis.

Fasting hormone

Glucagon.

Fed hormone

Insulin.

Hormone that activates a tyrosine kinase

Insulin.

Hormone that activates a G-coupled protein

Glucagon.

Hormone that stimulates the phosphorylation of regulated enzymes

Glucagon.

Hormone that stimulates de-phosphorylation of regulated enzymes

Insulin.

Hormone stimulated by stress hormones

Glucagon.

Hormone inhibited by stress hormones

Insulin.

Hormone that turns on glycolysis

Insulin.

Hormone that turns on gluconeogenesis

Glucagon.

Hormone that turns off glycogenesis

Glucagon.

Hormone that turns off glycogenolysis

Insulin.

Hormone that turns on lipogenesis and proteogenesis

Insulin.

Hormone that turns on lipolysis and proteolysis

Glucagon.

Anabolic hormone

Insulin.

Catabolic hormone

Glucagon.