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BioChem Exam 4 > Lecture 29: Glucose Anabolism (Gluconeogenesis) > Flashcards

Lecture 29: Glucose Anabolism (Gluconeogenesis) Flashcards

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1
Q

Gluconeogenesis Overview

What type of precersors create glucose?

A

noncarbohydrate precursors

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2
Q

Gluconeogenesis Overview

What are the main precursors?

A

Lactate
AA
Glycerol

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3
Q

Gluconeogenesis Overview

Where in the body does gluconeogenesis primarily take place?

A

The liver

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4
Q

Gluconeogenesis Overview

When is gluconeogensis important?

A

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

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5
Q

Gluconeogenesis Overview

Where does gluconeogenesis happen (cell wise)?

A

cytosol
mitrochondria
ER

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6
Q

Gluconeogenesis Overview

What is gluconeogensis in relation to glycolosis?

A

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

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7
Q

Gluconeogenesis Overview

What does glyconeogenesis have to combat Hexokinase?

A

Glucose-6-phosphotase

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8
Q

Gluconeogenesis Overview

What does glyconeogenesis have to combat phosphofructokinase?

A

Fructose 1,6-biphosphotase

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9
Q

Gluconeogenesis Overview

What does glyconeogenesis have to combat pyruvate kinase?

A

pyruvate carboxylase and phosphoenolpyruvate carboxykinase

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10
Q

Bypass of Pyruvate Kinase

How many energy consuming steps are there in this section?

A

2

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11
Q

Bypass of Pyruvate Kinase

What is the first step?

A

Pyruvate carboxylase concerts pyruvate to oxaloacetate

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12
Q

Bypass of Pyruvate Kinase

Where does this step take place?

A

Inside the mitrochondria

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13
Q

Bypass of Pyruvate Kinase

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

A

It cannot leave directly, it is shuttled out using malate

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14
Q

Bypass of Pyruvate Kinase

What does shuttled through Malate mean?

A

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

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15
Q

Bypass of Pyruvate Kinase

What molecules are used to transform pyruvate to oxaloacetate?

A

CO2 and H2O

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16
Q

Bypass of Pyruvate Kinase

What cofactor is needed for any carboxylation?

A

Biotin

17
Q

Bypass of Pyruvate Kinase

What is the second step?

A

Phosphoenolpyruvate caboxykinase converts ocaloacetate to Phosphoenopyruvate (PEP) via phosphorylation

18
Q

Bypass of Pyruvate Kinase

Where does this step happen?

A

within the cytosol

19
Q

Bypass of Pyruvate Kinase

What energy is used during step 2?

A

GTP

20
Q

Bypass of Pyruvate Kinase

What is the summed reaction?

A

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

21
Q

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What do cells use to bypass kinases?

A

phosphatase

22
Q

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What does phosphatase do?

A

hydrolyzes out the phosphate

23
Q

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What does Fructose 1,6-biphosphatase do?

A

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

24
Q

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

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

A

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)

25
Q

Hydrolytic reactions bypass phosphofrucotkinase and Hexokinase

What does glucose 6-phosphatase do?

A

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

26
Q

Gluconeogenesis and glycolysis are reciprocally regulated

What is reciprocally regulated?

A

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

27
Q

Gluconeogenesis and glycolysis are reciprocally regulated

What is a futile cycle?

A

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

28
Q

Gluconeogenesis and glycolysis are reciprocally regulated

Q from Lecture: Glycolysis yields how many high-energy phosphate bonds (ATP)?

A

2

29
Q

Gluconeogenesis and glycolysis are reciprocally regulated

Q from Lecture: Gluconeogenesis expends how many high-energy phosphate bonds (ATP and GTP)?

A

6

30
Q

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)?

A

4

31
Q

Gluconeogenesis and glycolysis are reciprocally regulated

What happens in the other pathway if one irreversible step is active in a pathway?

A

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

32
Q

Gluconeogenesis and glycolysis are reciprocally regulated

When is each pathway active?

A

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

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