E2 Gluconeogenesis (Bobby) Flashcards
T/F. GNG synthesizes glucose from carbohydrate precursors.
False; non-carbohydrate precursors
In order from most to least, which tissues perform GNG?
- Liver (90%) 2. Kidney (40%) 3. SI (minimal)
During fasting, which tissue performs GNG?
Kidney
What is the purpose of GNG?
Maintain blood glucose concentration
During which 3 states will GNG be required and what is used to make glucose in each?
- Starving- aa
- Fasting or low carbohydrate- aa
- Exercise- lactic acid and alanine
Which produces glucose faster, glycolysis or GNG?
Glycolysis
How much glucose can we store?
Enough for 1 day
Which hormone will stimulate GNG? Inhibit GNG?
Stimulate- Glucagon
Inhibit- Insulin
Matching.
1. Glycerol 2. Lactic Acid 3. Amino Acids
A. Produced during anaerobic glycolysis
B. TG backbone
C. Convert into pyruvate and OAA
- B
- A
- C
What tissue does glycerol come from?
Adipose
Glycerol is produced from TG’s by what process?
Hydrolysis
T/F. Glycerol is a major source of making glucose via GNG.
False
What are the 3 substrates of GNG?
Glycerol
Lactic Acid
Amino Acids
What enzyme converts glycerol —> glycerol phosphate?
Glycerol Kinase
T/F. GNG uses coupled rxn’s due to energy requirement.
True
What enzyme converts glycerol phosphate —> DHAP?
G-3-P DH
Once DHAP is produced, it can enter:
A. GNG
B. Glycolysis
C. Both
C. Both
Cells without mitochondria release which substrate?
Lactic Acid
T/F. Muscle release lactate via aerobic glycolysis.
False; anaerobic glycolysis
How are glucose and lactate exchanged between muscle and the liver?
Via Blood
Which enzyme facilitates pyruvate —> lactate?
Lactate DH
What condition would stimulate conversation of amino acids to glucose?
Starvation and low carbohydrates
Before becoming glucose, amino acids are turned into ________ (carbon skeleton).
Alpha ketoacid (pyruvate)
Which 2 amino acids are non-glucogenic and thus cannot be used as substrates for GNG?
Leucine and Lysine
What is the fate of an amino group after amino acid catabolism?
Use or Secrete it
What is the primary source of glucose for GNG at rest and during fasting?
Amino Acids
In which tissue does lactate —> pyruvate via lactate DH occur?
Liver
What are the 3 fates of alpha ketoacid?
- Energy
- Glucose
- Fatty Acid
What 4 factors direct breakdown of amino acids?
- High energy charge
- Hormones (glucagon)
- Low glucose concentration
- Tissue (liver vs. muscle)
What is the coenzyme of pyruvate carboxylase?
Biotin
What regulates pyruvate carboxylase?
Acetyl CoA
What enzyme facilitates alanine —> pyruvate?
ALT (alanine aminotransferase)
How many irreversible rxn’s are in glycolysis? GNG?
Glycolysis- 3
GNG- 4
Which irreversible GNG rxn requires ATP? GTP?
ATP= pyruvate ---> OAA GTP= OAA ---> PEP
Which GNG enzymes require Mg2+?
PEP carboxykinase
F-1-6 bisphosphatase
G-6- phosphatase
Pyruvate carboxylase is found in the mitochondria of which 2 tissues?
Liver and Kidney
T/F. Pyruvate carboxylase is not found in muscle and the brain.
False; it is found there but does not synthesize glucose
What is the location of the 1st half of the 1st obstacle of GNG?
Matrix
What effect does acetyl CoA have on pyruvate carboxylase?
Stimulate
What is the location of the 2nd half of the 1st obstacle of GNG?
Cytosol (pyruvate/ALA) or Matrix (lactate)
What enzyme facilitates OAA —> PEP?
PEP carboxykinase
Which specific obstacle requires ATP? GTP?
ATP- 1st half of 1
GTP- 2nd half of 1
What are the precursors for PEP carboxykinase?
Pyruvate, alanine, lactate
Which precursor(s) require a malate shuttle?
Pyruvate and Alanine
What structure does the malate shuttle transport?
OAA
What is location for the precursors for PEP carboxykinase?
1. Pyruvate 2. Lactate 3. Alanine
A. Cytosol
B. Matrix
- A
- B
- A
What enzyme facilitates OAA malate?
Malate DH
What is the location of lactate DH?
Cytosol
What is the key regulatory step in GNG?
F-1-6 bisphosphatase
What is the key regulatory step in glycolysis?
PFK
What enzyme facilitates F-6-P —> F-1,6-bisphosphate?
PFK
What inhibits the 2nd obstacle of GNG?
- Low energy
2. High F-6-P
What enzyme facilitates F-1,6-bisphosphate —> F-6-P?
F-1,6-bisphosphatase
Where does the 2nd obstacle take place?
Cytosol
What enzyme facilitates glucose —> G-6-P in the muscle?
Hexokinase
What enzyme facilitates G-6-P —> glucose?
G-6-phosphatase
What enzyme facilitates glucose —> G-6-P in the liver?
Glucokinase
What is the location of the 3rd obstacle of GNG?
Endoplasmic reticulum (rxn)
Where is glucose from the 3rd obstacle sent?
Cytosol
T/F. Muscle does have G-6-phosphatase?
False
T/F. In muscle, glucose is trapped when phosphorylated.
True
T/F. Glycogen in muscle will be released as glucose.
False
What two tissues release glucose, this maintaining glucose homeostasis?
Liver and Kidney
How many pyruvates are used in GNG per 1 glucose made?
2
How many total phosphate groups are produced via GNG per 1 glucose made?
6
How many ATP, GTP, and NADH are used in GNG per 1 glucose produced?
4 ATP, 2 GTP, 2 NADH
What secretes insulin?
Beta cells from the pancreas
What effect does insulin have on GNG?
Inhibit
What secretes glucagon?
Alpha cells in pancreas
What effect does glucagon have on GNG?
Stimulate
What effect does high AMP have on PFK?
Stimulate
What effect does high ATP have on F-1,6-bisphosphate?
Stimulate
What effect does high citrate have on PFK?
Inhibit
What effect does high ADP have on pyruvate carboxylase and PEP carboxykinase?
Inhibit
What effect does high F-2,6-bisphosphate have on F-1,6-bisphophatase?
Inhibit
What effect does low blood glucose concentration have on GNG? CAMP cascade?
GNG- stimulate
CAMP- stimulate
What effect does high citrate concentration have on GNG?
Stimulate
