Non-Oxidative Phase of the Pentose Phosphate Pathway

What is the first step in process one of the non-oxidative phase?

• Change ribulose 5-phosphate into glucose 6-phosphate

• Convert ribulose 5-phosphate into xylose 5-phosphate

• Transform ribose 5-phosphate into ribulose 5-phosphate

• Isomerize ribose 5-phosphate into glucose 5-phosphate

Which enzyme catalyzes the transformation of ribose 5-phosphate into ribulose 5-phosphate?

• Phosphopentose isomerase

• Phosphopentose epimerase

• Transaldolase

• Transketolase

What is the stereochemical difference between ribulose 5-phosphate and xylose 5-phosphate?

• They differ at the second carbon

• They differ at the first carbon

• They differ at the fourth carbon

• They differ at the third carbon

What is produced in process two of the non-oxidative phase?

• Ribulose 5-phosphate and xylose 5-phosphate

• Fructose 6-phosphate and glyceraldehyde 3-phosphate

• Ribose 5-phosphate and glucose 6-phosphate

• Xylose 5-phosphate and ribulose 5-phosphate

What cofactor is required by transketolase in process two?

• FADH2

• ATP

• NADPH

• Thiamine pyrophosphate

What type of sugar is formed when a two-carbon group is transferred to ribose 5-phosphate?

• Pentose

• Hexose

• Heptulose

• Tetrose

What is the final product of process three?

• Xylose 5-phosphate

• Glyceraldehyde 3-phosphate

• Fructose 6-phosphate

• Ribulose 5-phosphate

Which enzyme is used in both process three and process four?

• Phosphopentose epimerase

• Transaldolase

• Transketolase

• Phosphopentose isomerase

What is the net input of ribose 5-phosphate molecules in the non-oxidative phase?

• Two

• Four

• Three

• Five

What is the role of glyceraldehyde 3-phosphate in the pathway?

• It is an enzyme in the pathway

• It is converted into glucose 6-phosphate

• It is a precursor for ribose 5-phosphate

• It is a glycolytic intermediate