Flashcards in EXAM3_Gluconeogenesis Deck (21)
What are the four regulatory enzymes of Gluconeogenesis?
1. Pyruvate Carboxylase (requires ATP)
2. PEP carboxylase (via malate aspartate shuttle)
3. FBPase-1* (step 3)
4. G6Pase (step 1)
What/how much energy carriers needed for gluconeogenesis for each glucose?
4 ATP (pyruvate to OAA, and 1,3BPG)
2GTP (OAA to PEP)
2NADH (1,3BPG to GA3P)
What are 4 types of precursors that can be used for gluconeogenesis?
GLYCOGEN IS GLYCOGENOLYSIS NOT GLUCONEOGENESIS FAG!
3. AA's (glucogenic)
4. Propionyl-CoA (odd chain FA's only!)
What are the products of Beta oxidation
When using beta oxidation during fasting, we have a surplus of Acetyl coA, NADH, FADH2 which inhibits the TCA cycle (slows it down). We will have plenty of energy in the form of ATP but what is Lacking?
What is done to compensate?
Glucose for the brain and RBC's
Gluconeogenesis makes glucose from AA's/Muscle breakdown
FAT USED for ATP Energy but
Glucose required/used for brain and RBCs
When you see a CARBOXYLASE what should you immediately think?
BIOTIN (coenzyme of carboxylase)
Biotin Attaches CO2 to the molecule!
GET IT STRAIGHT!
During fasting, Beta oxidation produces acetyl-CoA which allosterically activates what enzyme of gluconeogenesis?
Pyruvate carboxylase has what two roles in the fasting state?
The malate aspartate shuttle is used for what?
What energy used/required?
used to transfer OAA into cytosol.
(using pep carboxylase) OAA-> PEP
USES 2 GTP
GTP in glycolysis is used for what?
OAA to PEP (pep carboxylase)
What is the rate limiting step in gluconeogenesis?
What is it inhibited by?
inhibited by high levels of F2,6-BisP
What activates the rate limiting step of gluconeogenesis?
think basic concept first then dive deeper:
Gluconeogenesis= low IG = phosphorylation of target enzy
FBP2 complex= activated>decreases F26bisP- low glycolysis- activated fbpase1- activates gluconeogenesis
Low IG > phosphorylation of FBP2 > active FBP2 > Decreases F2,6-bisP
- Inhibits PFK1 --> Glycolysis not active
- Activates FBPase1 --> Gluconeogenesis active
G6Pase is shared in two liver pathways:
Converts g6p to glucose into blood stream
what AA from muscle? what does it influence?
Alanine from muscle- influences rate of hepatic glucose synthesis
Cori Cycle links what two pathways in what two tissues?
1. Anaerobic glycolysis (muscle and RBC's) and
2. Liver gluconeogenesis (liver)
What is the physiological significance of the Cori Cycle?
Shifts the burden of RBC metabolism and Exercising muscle metabolism to the liver
What molecules cycle in the cori cycle? (what changes to what)
GLUCOSE >liver> LACTOSE >muscle> GLUCOSE>>liver
Glucose in liver (via gluconeogenesis) is anaerobically used in muscles and converted to LACTATE which is then used as a precursor in the liver again (in gluconeogenesis) to reform glucose
Why is starving yourself to lose weight (anorexia) such a bad idea?
Your brain requires glucose to live-
when no glucose is available, your body breaks down muscle (aa's) to make glucose.
Breaks down your skeletal and cardiac muscle
What are 3 protein sparing molecules?
1. Ketone bodies
2. Dietary Carbohydrates
3. Liver Glycogen
In beta oxidation (high NADH, FADH2, Acetyl CoA) what regulatory TCA enzyme is inhibited?
Why is that good?
- ensures OAA enters into gluconeogenesis