Ch 26 Pentose Phosphate Pathway (EXAM 4)

products of pentose phosphate pathway

ribose 5-phosphate and NADPH

Ribose 5 phosphate is a biosynthetic precursor of _________

nucleotides

NADPH is an ___________ _________

electron donor (reducing agent)

NADPH, a key product of the PPP, is the source of biosynthetic _________ _________

reducing power

what is the first phase of the pentose phosphate pathway?

oxidative generation of NADPH

G6P + 2 NADP + H2O → ribulose 5-phosphate + 2 NADPH + 2 H + CO2

What is the 2nd phase of the pentose phosphate pathway?

nonoxidative interconversion of a variety of sugars

The oxidative phase generates ___________ which is then isomerized into ____________ by ___________

ribulose 5-phosphate, ribose 5-phosphate, phosphopentose isomerase

Nonoxidative phase recycles ___ to ___ and is used in tissues requiring more ______ than R5P

6 R5P, 5 G6P, NADPH

what enzymes convert pentose phosphates to hexose phosphates, allowing the oxidative reactions to continue

transketolase, transaldolase

ATP is used in the nonoxidative phase, true or false

false

________ regulates partitioning into glycolysis versus pentose phosphate pathway

NADPH

The PPP and glycolysis are linked by

transketolase and transaldolase

The non-oxidative phase consists of ____ reactions. The net result of these reactions is the conversion of three ______ into 2 _______ and 1 __________.

3, pentoses, hexoses, triose

Xylulose 5-phosphate is formed from __________.

ribulose 5-phosphate

Transaldolase

3C + 7C → 6C + 4C

Transketolase

4C + 5C → 6C + 3C

The rate of the oxidative phase of the PPP is controlled by the

concentration of the NADP+

The first reaction of the pentose phosphate pathway, the dehydrogenation of glucose 6-phosphate by glucose 6-phosphate dehydrogenase is the ______________ step

rate-limiting

The PPP can operate in 4 distinct modes:

1. Ribose 5-phosphate needs > the needs for NADPH

2. The NADPH and ribose 5-phosphate needs are balanced

3. More NADPH is needed than ribose 5-phosphate

4. Both NADPH and ATP are required