Andrew Shore's Lectures Flashcards
What are the energy requirements for females?
2000 Kcal
How is glucose taken up by cells of any tissue?
By the glucose transporters GLUT-1, and GLUT- 3
What glut transporters are found at pancreatic Beta cells?
Glut-2, also found at the liver
What Glut transporter is found in muscle or fat?
Glut-4
What glut transporter is found in the small intestine and what is its function?
Glut-5, mainly fructose uptake
What is differences between the different glucose transporters apa from location?
1) they have different affinities for glucose because they have… 2) Different Km values 3) GLUT-2 has a Km value of **15,20** which means it has a lowwww affinity for glucose
Glut 1 and 3 have high affinities for glucose (km = 1) but what ablut Glut2 and 4?
They have high Km values, so a lower affinity for glucose. - Glut-2 regulates blood glucose levels (responds to insulin) - Glut-4 also responds to insulin
What are the three regulatory steps of glycolysis?
Steps 1,3 and 10 in glycolysis
What inhibits hexokinase?
Glucose 6 phophate (the product if the first step in glycolysis)
What is the hexokinase isozyme called in the liver?
Glucokinase
What are the energy requirements for males?
2500 kcal
What is phophofructokinase inhibited by?
1) By ATP 2) downregulatedby citrate
What is phophofructokinase activated by?
- AMP - fructose 2,6 bispohphate (increases affinity for fructose 6 phosphate, diminished inhibitory effect of ATP)
How does ATP inhibit phosphofructokinase?
At high concentrations, ATP bins to a regulatory site rather than the catalytic site of the enzyme
Hoe is phosphofructokinase under adenylate control?
Adenylate kinase; 1) When ATP being used up rapidly 2) ATP is formed from ADP 3) ADP + ADP to ATP + AMP (ATP used up, AMP becomes the signal for low- energy state)
What is substrate level phosphorylation?
“This type of phosphorylation involves the direct synthesis of ATP from ADP and a reactive intermediate, typically a high energy phosphate-containing molecule” Excerpt From: Kevin Ahern & Indira Rajagopal. “Biochemistry Free and Easy.” v2.0. DaVinci Press, 2012. iBooks. This material may be protected by copyright. Check out this book on the iBooks Store: https://itun.es/gb/iDeRG.n
What are the inputs of the link reaction?
Ipyruvate Cofactors: thiamine pyrophosphates (Vitamin B1), lipoic acid, CoA, NAD Enzyme: pyruvate dehydrogenase complex
How is the link reaction regulated?
ATP inhibits the link reaction Ca2+ and ADP activate pyruvate dehydrogenase
What are the products of the link reaction?
NADH Acetyl CoA (2 carbons) CO2+
Where does nadh get produced in the krebs cycle?
1) isocitrate to alpha ketogluterate 1) alpha ketogluterate to succinyl coA 1) malate to oxaloacete
How is Fructose 2,6 bisphosphate controlled?
- By the enzymes that are present on the same polypeptide chain;
- Phophofructokinase-1 phospohorylates Fructose 6-phophate to F2,6BP
- Fructose bisphosphatase 2 dephosphorylates Fructose 2,6 bisphosphate
What is the result of fructose 2,6 bisphosphate formation in the substrate cycle?
- Stimulates PFK-1 so
- Glycolysis is activated
- Gluconeogenesis is inhibited
What is the result of dephosphorylation of fructose 2,6 bisphosphate?
- Glycolysis is inactive
- Gluconeogenesis is active
How does glucagon regulate the substrate cycle involving fructose 2,6 bisphosphate?
- Increase in glucose levels
- Glucagon binds to Gs coupled receptor
- Andeylate cyclase, cAMP pathway produces protein kinase A
- Protein Kinase A shifts to cause FBPase 2 to dephosphorylate Fructose 2,6 bisphosphate so in the end you get less glycolysis and more gluconeogenesis
