Lecture 29: Glucose Anabolism (Gluconeogenesis)

Question 1

Gluconeogenesis Overview

What type of precersors create glucose?

Answer 1

noncarbohydrate precursors

Question 2

Gluconeogenesis Overview

What are the main precursors?

Answer 2

Lactate
AA
Glycerol

Question 3

Gluconeogenesis Overview

Where in the body does gluconeogenesis primarily take place?

Answer 3

The liver

Question 4

Gluconeogenesis Overview

When is gluconeogensis important?

Answer 4

During fasting and starvation
* when glucose cannot be obtained through fuel
** glucose is the primary fuel for the brain and only fuel for red blood cells

Question 5

Gluconeogenesis Overview

Where does gluconeogenesis happen (cell wise)?

Answer 5

cytosol
mitrochondria
ER

Question 6

Gluconeogenesis Overview

What is gluconeogensis in relation to glycolosis?

Answer 6

It opperates in the opposite direction to glycolosis but is not the reverse since glycolosis has 3 irreversible reactions that must be bypassed

Question 7

Gluconeogenesis Overview

What does glyconeogenesis have to combat Hexokinase?

Answer 7

Glucose-6-phosphotase

Question 8

Gluconeogenesis Overview

What does glyconeogenesis have to combat phosphofructokinase?

Answer 8

Fructose 1,6-biphosphotase

Question 9

Gluconeogenesis Overview

What does glyconeogenesis have to combat pyruvate kinase?

Answer 9

pyruvate carboxylase and phosphoenolpyruvate carboxykinase

Question 10

Bypass of Pyruvate Kinase

How many energy consuming steps are there in this section?

Answer 10

2

Question 11

Bypass of Pyruvate Kinase

What is the first step?

Answer 11

Pyruvate carboxylase concerts pyruvate to oxaloacetate

Question 12

Bypass of Pyruvate Kinase

Where does this step take place?

Answer 12

Inside the mitrochondria

Question 13

Bypass of Pyruvate Kinase

How does oxaloacetate leave the mitochondria for use in step 2?

Answer 13

It cannot leave directly, it is shuttled out using malate

Question 14

Bypass of Pyruvate Kinase

What does shuttled through Malate mean?

Answer 14

The oxaloacetate is reduced to malate to exit the mitochondia then oxidized back into oxaloacetate once in the cytosol (uses NADH and NAD)

Question 15

Bypass of Pyruvate Kinase

What molecules are used to transform pyruvate to oxaloacetate?

Answer 15

CO2 and H2O

Question 16

Bypass of Pyruvate Kinase

What cofactor is needed for any carboxylation?

Answer 16

Biotin

Question 17

Bypass of Pyruvate Kinase

What is the second step?

Answer 17

Phosphoenolpyruvate caboxykinase converts ocaloacetate to Phosphoenopyruvate (PEP) via phosphorylation

Question 18

Bypass of Pyruvate Kinase

Where does this step happen?

Answer 18

within the cytosol

Question 19

Bypass of Pyruvate Kinase

What energy is used during step 2?

Answer 19

GTP

Question 20

Bypass of Pyruvate Kinase

What is the summed reaction?

Answer 20

Pyruvate + ATP + GTP + H2O
–>
phosphoenolpyruvate + ADP + GDP + Pi + 2 H

Question 21

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What do cells use to bypass kinases?

Answer 21

phosphatase

Question 22

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What does phosphatase do?

Answer 22

hydrolyzes out the phosphate

Question 23

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What does Fructose 1,6-biphosphatase do?

Answer 23

converts Fructose 1,6 -phosphate to Fructore 6-phosphate by removing a phosphate from the C1 position

Question 24

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What type of enam is fructose 1,6-biphosphatase?

Answer 24

Allosteric, meaning it is oppositely regulated with PFK (if one is higher, the other is lower. This regulates if the cell is breaking down glucose or building it)

Question 25

# Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase What does glucose 6-phosphatase do?

Answer 25

hydrolyzes glucose-6-phosphate to glucose by removing the phosphate (mainly happens in liver)

Question 26

# Gluconeogenesis and glycolysis are reciprocally regulated What is reciprocally regulated?

Answer 26

With these two pathways being opposite, only one is able to be running at a time to not form a futile cycle

Question 27

# Gluconeogenesis and glycolysis are reciprocally regulated What is a futile cycle?

Answer 27

When both pathways, that have opposite effects, are simutaneously active in a cell and thus wasting energy

Question 28

# Gluconeogenesis and glycolysis are reciprocally regulated Q from Lecture: Glycolysis yields how many high-energy phosphate bonds (ATP)?

Answer 28

2

Question 29

# Gluconeogenesis and glycolysis are reciprocally regulated Q from Lecture: Gluconeogenesis expends how many high-energy phosphate bonds (ATP and GTP)?

Answer 29

6

Question 30

# Gluconeogenesis and glycolysis are reciprocally regulated Q from Lecture: A futile cycle of both pathways would waste how many high-energy phosphate bonds per cycle (ATP and GTP)?

Answer 30

4

Question 31

# Gluconeogenesis and glycolysis are reciprocally regulated What happens in the other pathway if one irreversible step is active in a pathway?

Answer 31

The matching opposite step in the other pathway is inhibited by the first

Question 32

# Gluconeogenesis and glycolysis are reciprocally regulated When is each pathway active?

Answer 32

If ATP is required, glycolysis is active If glucose is required, gluconeogenesis is active