Unit 4: Chapter 17, Gluconeogenesis

Question 1

Gluconeogenesis

Answer 1

Synthesis of glucose from pyruvate and related 3 and 4 carbon compounds (lactate, amino acids, and glycerol)

Question 2

Major sites of gluconeogenesis

Answer 2

Liver and kidney

Question 3

Reactions of glucogenesis of enzymes occur

Answer 3

cytoplasm, mitochondria, ER by enzymes

Question 4

During fasting or starvation ____ is important and why

Answer 4

gluconeogenesis since glucose is primary fuel for brain and only fuel for red blood cells

Question 5

gluconeogenesis converts ____ into each glucose

Answer 5

2 pyruvates

Question 6

Pruvate is formed from

Answer 6

lacid acid fermentation: muscle derived lactate in the liver by lactate dehydrogenase

Question 7

Carbon skeletons of some _____ can be converted into gluconeogenesis intermediates

Answer 7

amino acids

Question 8

___ is derived fom hydrolysis of triaglycerols which cna be converted into dihydroxyacetorne phosphate to be processed by glucogenesis or glycolysis

Answer 8

Glycerol

Question 9

What molecules can go through gluconeogenesis

Answer 9

LActate, amino acids, and glycerol

Question 10

Why is gluconeogenesis is not complete reversal of glycolysis?

Answer 10

Due to the 3 irreversible steps in glycolysis
Step 1: hexokinase
Step 3: phosphofructokinase (PFK)
Step 10: Pyruvate kinase

Question 11

To reverse irreversible steps of glycolysis, reactions must turn

Answer 11

endergonic

Question 12

Why is gluconeogensis expensive process?

Answer 12

Have to spend ATP and GTP since reaction is anabolic and endergonic

Question 13

Hexokinase will be reversed by and where is location

Answer 13

G6Phosphatase (G6Pase) and occurs in ER

Question 14

Phosphofructokinase will be reversed by and where is location

Answer 14

F 1,6 biphosphatase (F1, 6BPase) and occurs in cytosol

Question 15

Pyruvate kinase will be reversed by

Answer 15

Pyruvate Carboxylase which occurs in mitochondria and PEP Carboxykinase which occurs in cytoplasm

Question 16

Formation of _____ requires 2 enzymes of pyruvate carboxylase and PEP carboxykinase

Answer 16

phosphoneol (PEP) pyruvate
Step 10

Question 17

Conversion of step 10 begins with formation of ______

Answer 17

oxaloacetate

Question 18

What is reaction equation of formation oxaloacetate?

Answer 18

pyruvate + CO2 + ATP + H20 –> oxaloacetate + ADP + Pi + 2H+

Question 19

Formation of oxaloacetate occurs in

Answer 19

mitochondria

Question 20

Formation of oxaloaetate occurs in 3 stages by

Answer 20

pruvate carboxylase

Question 21

Pyruvate carboxylase requires what

Answer 21

Vitamin biotin as cofactor

Question 22

The molecule of ATP invested to form oxaloacetate to bypass step 10 is used to power

Answer 22

addition of CO2 to pyruvate
(carboxylation)

Question 23

Oxaloactetate is reduced to ______

Answer 23

maltate

Question 24

Why is oxaloacetate reduced to maltate?

Answer 24

• Maltate can be transported into the cytoplasm where it is reoxidized to oxaloacetate with generation of cytoplasmic NADH
• Oxaloacetate cannot simply just cross the mitcondria and go to cytoplasm since mitochondrial membrane does not have a transporter for oxaloacetate

Question 25

Oxaloacetate create phosphoneol (PEP) pyruvate in cytosol by

Answer 25

Phosphoenolpyruvate (PEP) carboxykinase

Question 26

When oxaloacetate becomes Phosphoneol pyruvate what occurs?

Answer 26

- CO2 that was added to pyruvate by pyruvate carboxylase comes off in this step (Decarboxylation) - Decarboxylation makes reaction exergonic

Question 27

What enzyme is involved in electron carriers such as NAD+/NADH and FADH/FADH2?

Answer 27

Dehydrogenase (substrate + dehydrogenase)

Question 28

What is reaction equation for formation of PEP pyruvate from oxaloacetate

Answer 28

Oxaloacetate + GTP --> PEP pyruvate + GDP + CO2

Question 29

Sume of reactions in step 10 of gluconeogenesis

Answer 29

pyruvate + ATP + GTP + H20 --> Phosphoenol (PEP) pyruvate + ADP + GDP + Pi + 2 H+

Question 30

Phosphatase

Answer 30

catalyzes reactions which removes phosphates

Question 31

Reactions of step 3 of gluconeogenesis

Answer 31

Fructose 1,6 biphosphate + H20 --> Fructose 6 Phosphate + Pi

Question 32

Which step of gluconeogenesis if generation of free glucose?

Answer 32

Step 1

Question 33

Why is the generation of free gluocse important?

Answer 33

Important control point

Question 34

What ocurs in final step of gluconeogenesis?

Answer 34

- Occurs only in liver - Glucose 6 phosphate is transported into the lumen of ER - catalyzed by glucose 6 phosphatase

Question 35

How many high transfer potential phosphoryl groups are spent in gluconeogenesis?

Answer 35

6

Question 36

Overall reaction for gluconeogenesis

Answer 36

2 pyruvate + 4 ATP + 2 GTP + 2 NADH + 2 H+ and 6 H20 --> glucose + 4ADP + 2 GDP + 6Pi + 2NAD+

Question 37

Is gluconeogensis exergonic or endergonic?

Answer 37

Exergonic

Question 38

Gluconeogensis and glycolysis are ____ reaction

Answer 38

Futile

Question 39

Futile reaction

Answer 39

occurs when two metabolic pathways run simultaneously in opposite directions and have no overall effect other than to burn ATP/GTP and heat produced