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MCBM > Gluconeogenesis > Flashcards

Gluconeogenesis Flashcards

1
Q

Glucuneogensis

A

new production of glucose. makes sugar

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2
Q

Liver glycogen depleted in:

A

overnight fast

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3
Q

Glucose is the major fuel in

A

brain

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4
Q

No glycogen stores in the

A

brain; gets it from bloodstrea.

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5
Q

Uses ketone bodies when

A

body is starved or uncontrolled diabetes from the breakdown of fat.

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6
Q

Where is the site for gluconeogenesis

A

Liver; a little in the renal cortex (kidney deals with excess lactate) and intestinal lining

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7
Q

3 carbon precursosrs that are starting point

A
  1. Lactate
  2. Pyruvate
  3. Glycerol
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8
Q

Where do most gluconeogenesis reaction occur

A

in the cytoplasm

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9
Q

3 irreversible steps are catalyzed by:

A
  1. Hexokinase
  2. Phosphofructokinase (Rate limiting, commited step)
  3. Pyruvate kinase (converts PEP to pyruvate and makes ATP)
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10
Q

In gluconeogenesis we need

A

NADH

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11
Q

Part of converting Pyruvate to PEP occurs in the

A

mitochondria

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12
Q

Pyruvate or _____usually initate gluconeogenesis

A

oxaloacetate

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13
Q

Pyruvate usually comes from

A

skeletal muscle via Cori cycle or nitrogen groups from protein breakdown in skeletal muscle which is sent to liver as alanine

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14
Q

Alanaine and pyruvate are

A

related; bc they only differ by the carbonyl group

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15
Q

Oxaloacetate comes from

A

aspartate or TCA cycle; it is an alpha keto acid (amino acid relative, whos sister is aspartate)

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16
Q

What shunts oxaloacetate from TCA cycle

A

malate shuttle

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17
Q

Glycerol is also a starting point for

A

gluconeiogenis; it is the backbone for tryglycerides.

18
Q

No way to build glucose from

A

acetyl CoA; one exception is glycerol

19
Q

Kinaseses add

A

phosphate

20
Q

Phosphateases remove

A

phosphate

21
Q

Glucose 6 phosphatase

A

removes phosphate grouop from glucose. Bc once its phosphorylated it stays in the cell and we dont want this

22
Q

Hook on CO2 in one step to make oxalocetate and take it off in next step to make PEP

A

drive reaction forward. Production of CO2 gas drives reaction forward

23
Q

Pyruvate carboxylase is found in

A

mitochondria

24
Q

CO2 gets attached to pyruvate via

A

pyruvate carboxylase and goes back into cytoplasm via malate shuttle and is converted from oxaloacetate to PEP

25
Q

Any time you see additon of CO2 you know it needs which cofactor

A

biotin

26
Q

No transporter for

A

oxaloacetate; you have to convert it to malate via malate shuttle and convert it back to oxoacelatate

27
Q

Need to take off CO2 and add on phosphate group to make

A

PEP

28
Q

Use GTP as a phosphate

A

donor

29
Q

PEP synthesis can occur

PEP carboxykinase step

A

in cytoplasm or mitochondira

30
Q

Use ATP and ___carrier in the first step of gluconeogenesis

A

biotin

31
Q

Use GTP for second step of

A

gluconeogenesis

32
Q

Last step of glycolysis and first step of gluconeogenesis are very highly:

A

regulated.

33
Q

Biotin attaches

A

to epsilon amino group of lysine. Makes a flexible structure to move CO2 around the structure

34
Q

The mitochondria is very :

A

impermeable; very selective and has a lot of proteins

35
Q

What are the mitochondrial transporters

A
  1. Pyruvate
  2. PEP
  3. Malate
    Not oxaloacetate!
36
Q

How are we going to decide whether or not we have to use the mallate shuttle to send oxalocetate out of the cell:

A

Depends on starting point and whether or not starting point is going to provide us with the NADH we need for gluconeogensis to occur

37
Q

If starting point is lactate (from muscle glycogen) the first step in the conversion of lactate back to pyruvate once it gets in liver cell provides us:

A

with NADH that we need to continue with gluconeogenesis; we dont need malate shuttle; we can convert oxaolocaetate to PEP in mitochondria using PEPCK. PEP transporter sends it to cytoplasm to go foward. Didnt have to borrow any reducing power from mitochondria!

38
Q

If its coming from alanine

protein breakdown

A

Alanine traseminates to pyruvate. No NADH is produced. Pyruvate goes to mitochondria, converts to oxaloacetate, which converts to malate. Send malate to cytoplasm through malate shuttle and convert it back to oxaloacetate (take off alcohol and make it a keto) using NAD+ and making NADH.

39
Q

If pyruvate is the main source of carbon:

A

the malate shuttle is used. By transporting malate to the cytoplasm, reducing power is also moved with it and NADH is produced as malate is converted to oxaloacetate. This NADH is needed for gluconeogenesis to proceed

40
Q

Malate needs ____to convert malate (from malate shuttle) to oxaloaceate

A

NAD+

MCBM (59 decks)

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