glycolysis gluconeogenisis Flashcards
(17 cards)
distinguish between the 3 types of dietary carbohydrates
- monosaccharides
- eg. glucose - disaccharides
- two monosaccharides joined by a glycosidic bond
- eg. maltose - polysaccharides
- polymers with hundreds of monosaccharides joined by glycosidic bond
- eg. starch (plants) and glycogen (animal)
identify the location of:
- glycolysis
- gluconeogensis
- citric acid cycle (TCA, pyruvate and oxidative phosphorylation)
- glycolysis -> cytoplasm
- gluconeogenisis -> liver (or kidney during starvation)
- citric acid cycle -> mitochondrial matrix
explain why some body parts uses glycolysis vs oxidative phosphorylation
- mitochondria = oxidative phosphorylation
- TCA cycle at mitochondrial matrix
- generates 30/32 ATP - no mitochondria = glycolysis
- generates 2 ATP only
- fastest ATP production for skeletal muscle during exercise
- RBC, nervous tissue (brain & retina) -> blood-brain barrier
outline the 2 types of carbohydrate (glucose) transport into cells
- symports
- glucose/Na+ symports used to transport glucose and galactose from small intestine into intestinal mucosal cells - uniports
- GLUT family facilitating the uptake of glucose from blood & small intestine into tissue cells
- GLUT 1: for blood-brain/retinal barrier
- GLUT 4: for glucose into adipose tissue, heart and skeletal muscle
which allosteric enzyme is responsible for the rate-limiting step of glycolysis (3)
phosphofructokinase
- catalyses third step of glycolytic pathway
- inhibited by citrate and ATP
- stimulated by AMP and fructose-2,6-bisphosphate
important features of glycolysis phase 1 (3)
- 2 ATP used (1x step 1, 1x step 3)
- phosphofructokinase rate-limiting step (step 3)
- F-1,6-bisP -> 2 GAP (step 4)
important features of glycolysis phase 2 (3)
- 4 ATP formed (2x step 7, 2x step 10)
- reduced co-factor 2 NADH (step 6) -> shuttles electrons to ETC for oxidative phosphorylation
- 2x pyruvate formed
outline ATP production in glycolysis
- used 2 ATP during phase 1
- gained 4 ATP during phase 2
- net gain of 2 ATP when breaking down 1x glucose -> 2x pyruvate
outline the net reaction of glycolysis
glucose + 2 ADP + 2 Pi + 2 NAD
->
2x pyruvate + 2 ATP + 2 NADH + 2H+ + 2 H20
what is gluconeogenesis and when does it occur
- synthesis of glucose from non-carb precursors
- occurs when dietary sources of glucose are not available + live has no supply of glycogen
what are precursors of gluconeogenesis (5)
- pyruvate
- lactate
- glycerol
- TCA cycle intermediates
- amino acids (except leucine & lysine)
- fatty acids, acetyl-CoA & L-amino acids not pre-cursors
identify key differences between glycolysis and gluconeogenesis
- 3 bypasses:
1. Step 10 (specific enzyme)
2. Step 3 (ATP input)
3. Step 1 (ATP input) - 2 ATP produced from glycolysis, 6 ATP used from gluconeogenesis
outline the net reaction of gluconeogenesis
2 pyruvate + 4 ATP + 2 GTP + 2 NADH + 2H+ + 6 H20
->
glucose + 2 NAD+ + 4 ADP + 2 GDP + 6 Pi
identify the importance of fructose-2,6-bisphosphate (2)
- f-2,6-bis is a allosteric ACTIVATOR of phosphofructokinase (glycolysis) and INHIBITOR of frucotse bisphosphatase (gluconeogenesis)
- efficient bc a single compound can control flux through two opposing pathways
outline importance of insulin and glucagon for diabetic patients
- insulin DECREASES blood glucose when concentrations are high (after meals)
- > activates glucose transport into cells via GLUT 4 transport - glucagon INCREASES blood glucose when conc. low
- > stimulates liver to release glucose into blood (from glycogen storage or gluconeogenesis)
identify the correlation between diabetes and cataract formation
- glucose transport into eye cells are not insulin-dependent
- in diabetic patients, cells in eye are constantly exposed to elevated intracellular glucose
- leads to production of sorbital via aldose reductase
- sorbital accumulation causes osmotic imbalances which leads to cataratic formation
difference between synthase and synthetase
synthase = no ATP synthetase = ATP
