Pentose Pathway

PPP catabolizes what

3 glucose molecules simultaneously

when is the PPP turned on

when glucose concentrations are high following a meal in liver or by insulin in other tissues

what does PPP produce

NADPH

ribose 5-phosphate

what is NADPH needed for

lipid synthesis

what is ribose 5-phosphate needed for

synthesis of nucleotides

synthesis of DNA and RNA

synthesis of proteins

where are enzymes for PPP located

cytosol

how many phases of PPP and are the independent or dependent

2

independent

phase 1 of PPP is it oxidative or nonoxidative, reversible or non reversible

oxidative

nonreversible

what does phase 1 PPP produce

6 molecules of NADPH

main product of the first step of phase 1 PPP

3 6-phosphogluconate

enzyme for phase 1 of PPP

Glucose 6-phosphate dehydrogenase (G6PD)

main product of step 2 of phase 1 PPP

3 ribulose 5-phosphate

phase 2 of PPP is it oxidative or nonoxidative, reversible or non reversible

nonoxidative

reversible

what does phase 2 of PPP produce

1 molecule of ribose 5-phosphate

what type of reactions occur in phase 2 of PPP

series of keto-aldo-epimer rearrangement reactions

is NADPH produced in phase 2 PPP

no

what cells do and dont make ribose-5 phosphate

all cells make it

EXCEPT mature RBCs

why do mature RBCs dont make ribose 5-phosphate

they lack nucleus and ribosomes

what happens if RBCs are deficient or have inactive G6PD

RBC hemolysis due to NADPH deficiency and glutathione peroxidase inactivity

hemolytic anemia

what causes G6PD deficiency

Genetic defect on X chromosome in Mediterranean and Afro Caribbean populations

what can be the causes of hemolytic anemia

infections

certain medications (aspirin, NSAIDs, certain antibiotics)

consumption of fava beans

enzyme in step 1 fructose catabolism

fructokinase

main product of step two of fructose catabolism

glyceraldehyde

when fructose is consumed by itself what is it converted to

glucose

if fructose is consumed in higher amounts with glucose what happens

it will continue down glycolysis, pyruvate catabolism and part of the CAC to synthesize fatty acids while glucose forms energy

fructose catabolism can lead to what

enhanced fat synthesis in the liver

enhanced fat synthesis in the liver can lead to what diseases

MASLD →MASH

what happens with triglyceride and LDL levels in fructose catabolism

raises blood triglyceride levels and LDL cholesterol levels

increased triglyceride levels leads to what

increase in fat storage in adipose tissue (obesity)

increased LDL cholesterol levels leads to what

increasing risk of CVD

enzyme in step 1 of galactose catabolism

galactokinase

main product of step 2 of galactose catabolism

glucose 1-phosphate

main enzyme of galactose catabolism

galactose 1-phosphate uridyl transferase

enzyme of lactose synthesis

lactose synthase

where is lactose synthesis

mammary gland

lactose synthesis

UDP Galactose + glucose → lactose

enzyme for synthesis of acidic sugars

UDP Glucose dehydrogenase

what makes lipids more water soluble

glucuronic acid

what is sorbitol and when can it be found

sugar alcohol

formed when blood glucose or fructose levels are high

what happens to the aldehyde or ketone when its reduced for sorbitol

reduced to alcohol

enzyme for sorbitol

aldose reductase