Metabolism Flashcards
What is the standard 16 carbon fatty acid found in the diet?
Palmitate
What enzymes are activated by insulin in the liver?
Glucokinase
Glycogen synthase
What enzymes are inhibited by insulin in the liver?
Glycogen Phosphorylase
Glucose -6 - Phosphotase
Phosphophenolpyruvate carboxykinase
Pyruvate carboxylase
What is the incretin effect and what enzymes are released?/
release of G.I hormones that stimulate insulin release
Glucagon like peptide -1
Gastric inhibitory peptide
What enzyme stimulates the formation of glycerol?
Dihydroxyacteone - 1
DHAP
What hormones are needed for the formation of TAGs via vLDL?
Lipoprotein lipase - breaks fatty acids off the vLDL
Diaglycerol Acyl Transferase (DGAT)
- reforming the fatty acids with glycerol in the adipocyte
What is the enzyme that reverses PFK-1?
Fructose 1,6 Bisphosphotase
What is the committed step in the pentose pathway?
Glucose - 6 - Phosphate being dehydrogenated by:
Glucose - 6 - phosphate dehydrogenase
What does Glycogen synthase use for its production?
G-6-P is turned into Glucose - 1 - phosphate
this is then activated into UDP glucose by G-1-P Uridlytrasnferase
Why can’t muscles contribute to blood glucose levels?
They lack Glucose-6-phosphates and thus are unable to remove the phosphate keeping the glucose in the cell.
What determines whether a glucose molecule is Alpha or Beta?
Where the hydroxy group is located on carbon 1.
If below it is alpha formation
What bond does fructose have?
Alpha 1-2 Glycosidic bond
What are the different type of starch structures and how do they affect digestion? with examples.
Type A - Latice structure with high surface area - easily digestible: wheat.
Type B - Helical structure - low surface area difficult to digest: Potato starch
Some cooking methods and storage methods cause starch to take on a helical structure which make it completely indigestible. what is this called?
Retrograde starch
turning type A into type B
What happens to carbohydrates that are not digested in the small intestine?
Within the first half of the colon, bacteria ferment them into short chained fatty acids, which can be exchanged for HCO3-
How do GLUT receptors differ form SGLT receptors?
GLUT allow glucose in down its concentration gradient
SGLT - force glucose against its concentration gradient
What GLUT receptors can carry fructose?
GLUT 2 and GLUT 5
What are the theoretical fates of glucose?
To be used by the cell for energy
Glycogen formation
Pentose pathway
Used to make triglycerides
Formation of glycoproteins - this is a small %
What is the yield from glycolysis?
2 ATP
2 NAHD+
2 Pyruvate
4 H+
Between what reactions do you get the ATP production during Glycolysis?
1,3 Bisphosphoglycerate - 3 Phosphoglycerate (x2)
Phosphophenolpyruvate - Pyruvate acid (x2)
What is the committed step for glycolysis?
PFK-1
What is the yield from Krebs cycle? and how does this equate to ATP production from one glucose?
3 NADH+ (x2)
1 GTP (x2)
1 FADH+ (x2)
24 ATP - taking into account both split molecules off the glucose molecule
How ATP does one glucose molecule yield?
36 ATP
What is the pentose pathway important for?
NADPH production - reductive abilites
Ribose - 5 - phospahte - DNA and RNA synthesis
In order for glycogen to be formed, what must happen to Glucose - 6 - phosphate and what enzyme achieves this?
converted to glucose - 1 - phosphate
phospho- glucomutase
What enzyme reverses hexokinase/ Glucokinase activity? and where is it found and what up-regulates it?
Glucose - 6 - phosphatase.
expressed in R.E.R
- Glucagon
- adrenaline
- cortisol
What are the two enzymes needed to reverse pyruvate?
[Pyruvate Carboxylase] creating Oxaloacetate which is then converted to Phosphophenopyruvate via:
[Phosphophenopyruvate Carboxykinase]
What protein kinase does insulin work through?
Protein kinase B
How does Glucagon work intracellularly?
Increases cAMP levels. induces PKA
What is fasting glucose level normally? and what are levels post prandial?
4-5mmol
8-12mmol
What are the functions of insulin in adipose tissue?
Supress lipolysis
Increase GLUT 4 and fatty acid synthesis
What does DGAT stand for and when is it used?
Diacylglycerol acyl transferase
Used to convert Fatty acids into triglycerides
What is the target of orlistat?
Pancreatic lipases and colic lipsases
What is the fate of triglycerides and fatty acids?
Storage - adipose tissue
Beta - oxidation
Ketone production
Phospholipid production
How much ATP does a 16 carbon fatty acid (Palmitate) produce?
106 ATP
What are the two key regulatory hormones in fatty acid synthesis?
Acetly CoA carboxylase
Fatty Acid synthesis
What does Acetly CoA carboxylase need in order to produce malonyl CoA
Biotin
ATP
CO2
Where does the enzyme fatty acid synthesis work? and what does it require?
Cytosol of the cell
NADPH - derived from pentose pathway
What are the major ketones produced?
Acetoacetate
Acetone
Beta - hydroxybutyrate
Name two essential fatty acids?
and why are they important?
w- 3
w- 6
precursors for: eicosanoids and prostanoids - pro-inflammatory responders
Decrease LDL
**high levels may also lower HDL
What 3 main areas does insulin regulate triglyceride production?
Up-regulates GLUT 4
Acetyl CoA Carboxylase enzyme
Lipoprotein lipase
What occurs to the lipoprotein lipase activity during the fed state in muscles and cardiac tissue?
Activity goes down - the tissues don’t need fatty acids within the cells for energy
