2.1-Secondary Carb Pathways

Question 1

Where are the three steps in glycolysis that Fructose can enter (what tissue type for each?)

Answer 1

1. Step to Fructose-6-Phosphate (from adipose tissue-Burning Fat goes to Fructose!) 2. Step 4b DHAP (Liver) 3. Step 4a G-3-P (Liver)

Question 2

What are the three sources of Fructose in our diet? How is High Fructose Corn Syrup different from Sucrose?

Answer 2

1. Pure Fructose 2. High Fructose Corn Syrup 3. Sucrose. HFC=NO covalent bonds; Sucrose=Covalently bonded

Question 3

Which enzyme hydrolyses Sucrose in the small intestine? What “type” of enzyme is it?

Answer 3

A “Brush Border” Enzyme-Sucrase Isomaltase (S.I.)

Question 4

What happens with an SI deficiency? Think Biome taking over…

Answer 4

osmotic-fermentive diarrhea

Question 5

Which GLUT transporter absorbs Fructose from the Gut into the cell? Which GLUT transports Fructose from the cell to the Blood?

Answer 5

Gut to Cell= GLUT5; Cell to Blood= GLUT2

Question 6

Is there a limit to Fructose absorption in the Small Intestine?

Answer 6

Yes, Excess goes to the colon and causes Diarrhea

Question 7

What are the two locations for Fructose catabolism? What is the bigger one?

Answer 7

Muscle & Liver… MUCH more going on in the liver

Question 8

What is the step that gets Fructose into Glycolysis in muscle cells? What is the enzyme used?

Answer 8

Fructose ——->Fructose-6-Phosphate. The enzyme that does this is HEXOKINASE (WEIRD, I know. Phosphorylating a 6 carbon molecule…)

Question 9

What are the two key enzymes in getting Fructose into glycolysis in the LIVER? Which one is “fast”, which one is “slow”?

Answer 9

1. FructoKinase 2. Aldolase B

Question 10

What does FructoKinase do?

Answer 10

Phosphorylates Fructose—->Fructose-1-Phosphate. WHAAA?

Question 11

What does Aldolase B do?

Answer 11

Splits Fructose-1-Phosphate into 1.G-3-P and 2.DiHydroxyAcetonePhosphate (DHAP)

Question 12

What gets by bypassed in Fructose metabolism in the liver? What is the consequence? THIS HITS HOME :)

Answer 12

PFK1 gets bypassed making more Acetyl-CoA which will then start making FAT

Question 13

What is the result of high Fructose intake and then sequestering of inorganic Phosphate?

Answer 13

HyperUricemia and therefore GOUT. LOOK OUT cause its comin for ya! (ALDOLASE B gets backed up and saturated)

Question 14

Which is more severe a FructoKinase deficiency or an Aldolase B deficiency? Why?

Answer 14

Aldolase B deficiency is more severe because the F-1-P gets stuck in the cell and gathers iPhosphate. (FructoKinase deficiency just excretes fructose from the body)

Question 15

How does the less popular monosaccharide MANNOSE enter glycolysis?

Answer 15

Mannose—->Fructose-6-Phosphate (by a couple of enzymes) and you’re good to go!

Question 16

What is the sugar alcohol made from glucose in the cell? What unique function does this have?

Answer 16

Sorbitol! Helps trap glucose in the cell!

Question 17

Which enzyme is lacking in the lens, nerves, and kidney that causes a build up of sorbitol?

Answer 17

Sorbitol DeHydrogenase

Question 18

What are the 4 enzymes that participate in the conversion of Galactose to G-6-P?

Answer 18

1. GalactoKinase 2. Galactose-1-Phosphate Uridylyl Transferase 3. UDP-Galactose-4-Epimerase 4.PhosphoGlucoMutase

Question 19

What are the two alternate names for the Pentose Phosphate Pathway?

Answer 19

1.Hexose MonoPhosphate Shunt 2. PhosphoGluconate Pathway

Question 20

What are the two main products of the Pentose Phosphate Pathway?

Answer 20

1. NADPH (for anabolism of things-steriods,complex carbs) 2. Ribose-5-Phosphate (for NucleoTides!)

Question 21

What fatty acid synthesis areas are really active in PPP? What is the important area that IS NOT active in PPP?

Answer 21

MammaryGlands, Adipose Tissue, Adrenal Cortex, Liver…..MUSCLE dont care

Question 22

What is the key reaction in the oxidative PPP pathway?

Answer 22

Glucose-6-P—–>Lactone USING: Glucose-6-Phosphate Dehydgrogenase

Question 23

How many NADPHs are yielded from the oxidative PPP pathway?

Answer 23

2 NADPH’s

Question 24

What is the key of the NON oxidative pathway?

Answer 24

If cell needs NADPH to build things, it can recycle Ribose-5-Phosphate

Question 25

What happens when you are low on Ribose-5-Phosphate? What are the two starting ingredients?

Answer 25

Reverse PPP and make more from Fructose-6-Phosphate and Glyceraldehyde-3-Phospahte?

Question 26

Which part of PPP is dominant when NADPH and Ribose-5-Phosphate are balanced your cell?

Answer 26

The Oxidative Part

Question 27

What happens when you are low on NADPH?

Answer 27

GlucoNeoGenesis will make more Glucose-6-Phosphate to then go through the Oxidative PPP!

Question 28

What happens when BOTH NADPH and Ribose-5-Phosphate are low?

Answer 28

Couple PPP with Glycolysis!

Question 29

What is the enzyme that detoxifies H2O2 to H2O? What enzyme rejuvenates this enzyme to get back to work?

Answer 29

Glut-A-Thione Peroxidase…Reduced by GlutAThione Reductase

Question 30

What is the antioxidant GlutAThione made of?

Answer 30

3 amino acids (a tripeptide!)

Question 31

What is the #1 genetic deficiency in all Z world?! Where is the first place you will see it??

Answer 31

Glucose-6-P Dehydrogenase Deficiency..in the RBCs

Question 32

Why is the #1 genetic deficiency a problem in RBCs?

Answer 32

There is lots of Free Radical Oxygen in RBCs and they do not have the enzyme to take care of it!

Question 33

What is the clinical name for the deficiency of the enzyme Glucose-6-Phosphotase Dehydrogenase in a RBC?

Answer 33

Hemolytic Anemia

Question 34

Which enzyme converts Glucose to Sorbitol?

Answer 34

Aldose Reductase

Question 35

Is G6DP inhibited by NADPH?

Answer 35

NO

Question 36

Why is reduced glutathione used in RBCs?

Answer 36

To produce NADPH