Biochemistry: The Pentose Phosphate Pathway and Related Metabolism

This set of flashcards covers key vocabulary and concepts related to the pentose phosphate pathway, its phases, regulation, and connections to other metabolic processes.

Pentose Phosphate Pathway (PPP)

A metabolic pathway that catalyzes the exchange of three-carbon and six-carbon intermediates with five-carbon sugars.

NADPH

A reducing agent generated by the pentose phosphate pathway, used in biosynthetic reactions and cellular defense.

Oxidative Phase

The first phase of the PPP, which oxidizes glucose 6-phosphate, producing NADPH and ribulose 5-phosphate.

Non-oxidative Phase

The second phase of the PPP, which interconverts ribulose 5-phosphate with various carbon sugar intermediates.

Glucose 6-Phosphate Dehydrogenase

The enzyme that catalyzes the committed step in the oxidative phase of the PPP, converting glucose 6-phosphate to 6-phosphogluconate.

Transketolase

An enzyme that catalyzes the transfer of two-carbon units between sugars in the non-oxidative phase of the PPP.

Transaldolase

An enzyme that catalyzes the transfer of three-carbon units between sugars in the non-oxidative phase of the PPP.

Regulation of PPP

The pathway is regulated by NADP+ concentration and NADPH levels.

Ribose 5-Phosphate

A five-carbon sugar produced in the PPP, crucial for nucleotide synthesis.

NADH

A coenzyme that plays a central role in metabolic processes, produced in other pathways such as glycolysis and the citric acid cycle.

Metabolic flux

The rate at which substrates and products are interconverted in metabolic processes, influenced by cellular needs.

Fatty Acid Synthesis

The metabolic process of creating fat molecules (fatty acids) from acetyl CoA, requiring NADPH as a reducing power.

Oxidative Stress

A condition characterized by excessive reactive oxygen species in cells, which can cause damage; NADPH is crucial for cellular defense against ROS.

Glyceraldehyde 3-Phosphate (GAP)

A three-carbon intermediate that can be produced in the non-oxidative phase of the PPP and is a key molecule in glycolysis.

Fructose 6-Phosphate

A six-carbon sugar phosphate produced in the non-oxidative phase of the PPP, involved in glycolysis.

High demand for NADPH

Occurs in biosynthetic pathways such as fatty acid synthesis, where NADPH production from the PPP is prioritized.

Three-carbon and six-carbon intermediates

Intermediates exchanged by the pentose phosphate pathway that play significant roles in cellular metabolism.

Calvin Cycle

A series of biochemical reactions in photosynthesis that also requires NADPH generated by the PPP.

Photosynthesis

The process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water, involving NADPH from the PPP.

Cytoplasm

The site within the cell where the reactions of the pentose phosphate pathway take place.

Hexose Monophosphate Shunt

Another name for the pentose phosphate pathway, emphasizing its role in the metabolism of hexose monosaccharides.