Gluconeogenesis Flashcards Preview

MCBM > Gluconeogenesis > Flashcards

Flashcards in Gluconeogenesis Deck (40):
1

Glucuneogensis

new production of glucose. makes sugar

2

Liver glycogen depleted in:

overnight fast

3

Glucose is the major fuel in

brain

4

No glycogen stores in the

brain; gets it from bloodstrea.

5

Uses ketone bodies when

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

6

Where is the site for gluconeogenesis

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

7

3 carbon precursosrs that are starting point

1. Lactate
2. Pyruvate
3. Glycerol

8

Where do most gluconeogenesis reaction occur

in the cytoplasm

9

3 irreversible steps are catalyzed by:

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

10

In gluconeogenesis we need

NADH

11

Part of converting Pyruvate to PEP occurs in the

mitochondria

12

Pyruvate or _____usually initate gluconeogenesis

oxaloacetate

13

Pyruvate usually comes from

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

14

Alanaine and pyruvate are

related; bc they only differ by the carbonyl group

15

Oxaloacetate comes from

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

16

What shunts oxaloacetate from TCA cycle

malate shuttle

17

Glycerol is also a starting point for

gluconeiogenis; it is the backbone for tryglycerides.

18

No way to build glucose from

acetyl CoA; one exception is glycerol

19

Kinaseses add

phosphate

20

Phosphateases remove

phosphate

21

Glucose 6 phosphatase

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

22

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

drive reaction forward. Production of CO2 gas drives reaction forward

23

Pyruvate carboxylase is found in

mitochondria

24

CO2 gets attached to pyruvate via

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

25

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

biotin

26

No transporter for

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

27

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

PEP

28

Use GTP as a phosphate

donor

29

PEP synthesis can occur
(PEP carboxykinase step)

in cytoplasm or mitochondira

30

Use ATP and ___carrier in the first step of gluconeogenesis

biotin

31

Use GTP for second step of

gluconeogenesis

32

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

regulated.

33

Biotin attaches

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

34

The mitochondria is very :

impermeable; very selective and has a lot of proteins

35

What are the mitochondrial transporters

1. Pyruvate
2. PEP
3. Malate
Not oxaloacetate!

36

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

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

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:

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

If its coming from alanine
(protein breakdown)

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

If pyruvate is the main source of carbon:

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

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

NAD+