Pentose Phosphate Shunt

Question 1

where are the enzymes for the pentose phosphate shunt found

Answer 1

in the cytosol

Question 2

important products of the pentose phosphate shunt?

Answer 2

NADPH and ribose-5-phosphate (R5P)

Question 3

The first three steps are referred to as the ___ phase

Answer 3

oxidative

Question 4

oxidative phase

G6P is converted to what? what is released

Answer 4

G6P converted to Ru5_

Co2 is released

Question 5

what is formed during the oxidative phase per glucose

Answer 5

6 NADPH are formed

3 co2 is released

3 Ru5P

Question 6

enzymes invovled in the oxidative phase (G6P–>Ru5P)

Answer 6

two dehydrogenases and lactose

Question 7

phase after the oxidaitive phase?

Answer 7

nonoxidative phase

Question 8

nonoxidative phase

converts Ru5P to

Answer 8

intermediates of the glycolytic pathway

Ru5P → 2 F6P + 1 GAP

Question 9

isomerase, epimerase, transketolase, and transaldolase

are all invovled in

Answer 9

non oxidative phase

Ru5P → 2 F6P + 1 GAP

Question 10

nonoxidative phase

the enzyme ___ has TPP as a prosthetic group for transferring C2 groups

Answer 10

transketolase

Question 11

how many Co2 does the oxidative phase yeild?

Answer 11

3

glucose has 18 carbons = three CO2 (3 carbons), three Ru5P (15 carbons), and six NADPH

Question 12

how many Ru5P does the oxidative phase yeidl?

Answer 12

3 Ru5P

glucose has 18 carbons = three CO2 (3 carbons), three Ru5P (15 carbons), and six NADPH

Question 13

how many nadph does the oxidative phase yield?

Answer 13

6 nadph

glucose has 18 carbons = three CO2 (3 carbons), three Ru5P (15 carbons), and six NADPH

Question 14

In the nonoxidative phase, we use the three Ru5P to make___ before F6P and GAP

Answer 14

one R5P and two Xu5P

Question 15

one R5P and two Xu5P from the 3 Ru5P are used to make

Answer 15

two F6P and one GAP

Question 16

from phosphate shunt, you gain 6 nadph at the expense of

Answer 16

one GAP → three CO2

Question 17

___ is used primarily as a reductant,

Answer 17

NADPH

Question 18

NAD+ is used primarily as an ___

Answer 18

oxidant

Question 19

which tissues have pentose phopshate pathways?

Answer 19

Question 20

The main uses of NADPH are in ___ and ___

Answer 20

biosynthesis and detoxification

Question 21

**_NADPH_** is used by **_cytochrome P450_**  in the
 small intestine (and liver) to detoxify \_\_\_\_

Answer 21

xenobiotics

Question 22

In red blood cells, NADPH is needed to detoxify

Answer 22

reactive oxygen species (ROS)

Question 23

Most common human enzyme deficiency is

Answer 23

G6PDH Deficiency

Question 24

consequences of G6PDH Deficiency

Answer 24

Favism (Hemolytic anemia) when they take antimalralial drugs (quinine or chloroquine)

Selective advantage where malaria is endemic

Question 25

why does G6PDH Deficiency have an advantage with malaria?

Answer 25

it’s better to pay the metabolic cost of a faster rate of turnover of RBC’s than to die from malaria

Question 26

If we need ribose but not NADPH, we can

Answer 26

un the nonoxidative phase of the Shunt in reverse, starting with F6P and GAP and ending with R5P

Question 27

If we need ribose but not NADPH, what do you start with?

Answer 27

starting with F6P and GAP and ending with R5P

Question 28

what do we need ribose for?

Answer 28

information storage, energy transfer, oxidation/reduction reactions, and enzyme catalysis

Question 29

how does the body get both nadph and ribose from the shunt?

Answer 29

run just the oxidative phase of the Shunt and convert all of the Ru5P produced to R5P

Question 30

Any ratio other than 2 nadph/ribose can be obtained by

Answer 30

running the oxidative phase in the forward direction and the nonoxidative phase in either direction.

Question 31

In liver, up to \_\_\_\_% of the Glu metabolized goes through the pentose phosphate shunt

Answer 31

30

Question 32

• G6Pase is only present in

Answer 32

liver and to a small extent in kidney

Question 33

Glu is the primary fuel in (2)

Answer 33

brain and RBC

Question 34

During \_\_\_\_, liver uses its glycogen to maintain blood Glu

Answer 34

fasting

Question 35

**_Glucose-6-P_** + NADP+ —\> **_6-Phosphoglucono-δ-lactone_** + NADPH enzyme?

Answer 35

Glucose-6-P Dehydrogenase

Question 36

6-Phosphoglucono-δ-lactone + H2O —\>

Answer 36

6-Phosphogluconate

Question 37

6-Phosphoglucono-δ-lactone + H2O —\> 6-Phosphogluconate enzyme?

Answer 37

6-Phosphoglucono Lactonase

Question 38

6-Phosphoglucono-δ-lactone + H2O —\> 6-Phosphogluconate rxn type?

Answer 38

hydrolysis

Question 39

6-Phosphogluconate + NADP+ —\> Ribulose-5-P + NADPH + CO2 enzyme?

Answer 39

6-Phosphogluconate Dehydrogenase

Question 40

6-Phosphogluconate + NADP+ —\> Ribulose-5-P + NADPH + CO2 reaction type?

Answer 40

oxidation, decarboxylatoon

Question 41

6-Phosphogluconate + NADP+ —\>

Answer 41

Ribulose-5-P + NADPH + CO2

Question 42

3 Ribulose-5-P \<—\>

Answer 42

Ribose-5-P 2 Xylulose-5-P

Question 43

Ribulose-5-P \<—\> Ribose-5-P enzyme?

Answer 43

Ribulose-5-P Isomerase

Question 44

Ribulose-5-P \<—\> Ribose-5-P reaction type?

Answer 44

isomerization

Question 45

Ribulose-5-P \<—\> Xylulose-5-P type?

Answer 45

epimierization

Question 46

Ribulose-5-P \<—\> Xylulose-5-P enzyme?

Answer 46

Ribulose-5-P Epimerase

Question 47

Ribose-5-P + Xylulose-5-P \<—\> Glyceraldehyde-3-P + Sedoheptulose-7-P enzyme?

Answer 47

Transketolase

Question 48

Ribose-5-P + Xylulose-5-P \<—\> Glyceraldehyde-3-P + Sedoheptulose-7-P ## Footnote reactino type

Answer 48

Intermolecular Transfer of a C2 Unit (

Question 49

Ribose-5-P + Xylulose-5-P \<—\>

Answer 49

Glyceraldehyde-3-P + Sedoheptulose-7-P

Question 50

Glyceraldehyde-3-P + Sedoheptulose-7-P \<—\>

Answer 50

Fructose-6-P + Erythrose-4-P

Question 51

Glyceraldehyde-3-P + Sedoheptulose-7-P \<—\> Fructose-6-P + Erythrose-4-P enzyme?

Answer 51

Transaldolase

Question 52

Glyceraldehyde-3-P + Sedoheptulose-7-P \<—\> Fructose-6-P + Erythrose-4-P enzyme type?

Answer 52

Intermolecular Transfer of a C3 Unit

Question 53

Erythrose-4-P + Xylulose-5-P \<—\> Fructose-6-P + Glyceraldehyde-3-P enzyme?

Answer 53

Transketolase

Question 54

Erythrose-4-P + Xylulose-5-P \<—\> Fructose-6-P + Glyceraldehyde-3-P reaction type?

Answer 54

Intermolecular Transfer of a C2 Unit (Dihydroxyethyl)

Question 55

Erythrose-4-P + Xylulose-5-P \<—\>

Answer 55

Fructose-6-P + Glyceraldehyde-3-P

Question 56

As glycogen is depleted, gluconeogenesis kicks in using what as substrates?

Answer 56

lactate, pyruvate, CAC intermediates, and most aa

Question 57

what in glucogensis are the Three bypasses that circumvent three glycolytic steps that are irreversible? what is the benefit to them?

Answer 57

The three Bypasses provide **thermodynamically favored alternative steps**

Question 58

first step in glucogenesis? what is used up?

Answer 58

pyruvate --\> oxaloacetate via pyruvate carboxylase **1 atp is used up in the activation of bicarbonate** (which is needed to run the rxn)

Question 59

pyruvate --\> oxaloacetate ## Footnote via \_\_\_

Answer 59

pyruvate carboxylase

Question 60

**pyruvate carboxylase** catalyzes the _carboxylation_ of the –\_\_\_ group of Pyruvate

Answer 60

CH3

Question 61

what is needed for pyruvate to be converted to oxaloacetate?

Answer 61

bicarbonate must be activated at the expense of an ATP in a process that involves the enzyme’s prosthetic group, biotin

Question 62

Bicarbonate is activated by the transfer of a\_\_ from ATP

Answer 62

Phosphoryl group (PO3)

Question 63

what convertes oxaloacetete to PEP?

Answer 63

y PEP carboxykinase,

Question 64

what is generated from oxaloacetate ---\> PEP what is consumed?

Answer 64

consumed? **GDP goes to GTP** released? **CO2**

Question 65

Gluconeogenesis begins in the \_\_\_

Answer 65

mitochondrion

Question 66

• The only aa’s that cannot contribute to gluconeo are

Answer 66

Leu and Lys

Question 67

One minor exception to mito as the starting point for gluconeogenesis is \_\_\_\_?

Answer 67

glycerol

Question 68

glycerol which gets converted to DHAP in the \_\_\_

Answer 68

cytosol

Question 69

There is no transport system for OAA, but it can exit mito by the\_\_\_ in reverse after first being reduced to malate.

Answer 69

Mal/Asp shuttle running

Question 70

where is OAA converted back to?

Answer 70

cytosol

Question 71

Human mito contain PEPCK, and there is a ___ transporter

Answer 71

PEP

Question 72

All glycolytic reactions from ___ are reversible

Answer 72

PEP back to FBP

Question 73

Bypass\_\_\_, present in liver, is G6Pase

Answer 73

3

Question 74

When ATP demands in muscle exceed the capacity of Ox Phos for generating ATP, ___ is produced

Answer 74

lactate

Question 75

The lactate is carried to the liver where it is converted to

Answer 75

Glu and released back into the bloodstream

Question 76

what is the cori cycle?

Answer 76

The lactate is carried to the liver where it is converted to Glu and released back into the bloodstream

Question 77

the cori cycle after/durign exercise?

Answer 77

• After exercise this continues as muscle glycogen stores are replenished

Question 78

what is oxygen debt

Answer 78

The amount of O2 consumed in liver during this rebuilding of muscle glycogen