Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
3 Fates of glucose
|
1.) storage to glycogen, starch, and sucrose
2.) oxidation via glycolysis to make pyruvate 3.) oxidation by pentose phosphate pathway to make ribose 5-phosphate |
|
|
Preparatory phase
|
phosphorylation of glucose and its conversion to glyceraldehyde 3-phosphate
|
|
|
Payoff phase
|
oxidative conversion of glyceraldehyde 3-phosphate to pyruvate and the coupled formatin of ATP and NADH
|
|
|
Step 1: Phosphorylation of Glucose
|
- Glucose phosphorylation at C-6 making Glucose 6-phosphate
- use 1 ATP - catalyzed by hexokinase - 1st irreversible and regulated step |
|
|
Step 2: Conversion of G6P to what?
|
- G6P to Fructose 6-phosphate
- catalyzed by Phophohexose Isomerase - reversible |
|
|
Step 3: Phosphorylation of F6P to what?
|
- phosphorylation of F6P to Fructose 1,6-bisphosphate
- use 1 ATP - catalyzed by Phosphofructokinase-1 - 2nd irreversible - major point of regulation |
|
|
Step 4: Cleavage of F16BP to what?
|
- cleavage of F16BP to Dihydroxyacetone phosphate and Glyceraldehyde 3-phosphate
- catalyzed by Aldolase - reversible |
|
|
Step 5: Interconversion of the triose phosphates
|
- Dihydroxyacetone phosphate is converted to Glyceraldehyde 3-phosphate by Triose phosphate isomerase
- reversible |
|
|
Step 6: Oxidation of Glyceraldehyde 3-phosphate to what?
|
- oxidation of glyc3P to 1,3-bisphosphoglycerate
- glyc3P is phosphorylated with inorganic phophate - catalyzed by Glyceraldehyde 3-phosphate dehydrogenase - reduction of NAD+ (electron acceptor) to NADH and H+ - free energy conserved in phosphate group formation - reversible - everything x2 |
|
|
Step 7: Phophoryl transfer from 13BPG to ADP
|
- generate 2 ATP
- phosphoryl grp from 13BPG donated to ADP to make ATP - forms 3-Phospoglycerate - catalyzed by phophoglycerate kinase (named for the reversible rxn) |
|
|
Step 8: 3-Phosphoglycerate what?
|
- 3-Phosphoglycerate to 2-Phosphoglycerate
- catalyzed by phophoglycerate mutase - reversible |
|
|
Step 9: Dehydration of 2-Phosphoglycerate to what?
|
- 2-Phosphoglycerate to Phosphoenolpyruvate
- removes H2O causes redistribution of energy - has high phosphoryl grp transfer potential - reversible |
|
|
Step 10: Transfer of phosphoryl group from Phosphoenolpyruvate to ADP
|
- PEP donates its Pi group to ADP making ATP and pyruvate
- catalyzed by pyruvate kinase - makes 2 more ATPs - 3rd irreversible step and regulated |
|
|
3 enzymes that are regulated
|
1.) hexokinase
2.) phosphofructokinase-1 3.) pyruvate kinase |
|
|
How is energy conserved in glycolysis?
|
- by the couple phosphorylation of 4 ADP to ATP by high energy cps
- in formation of 2 NADH per 1 glucose |
|
|
What are the products of glycolysis?
|
- 2 pyruvates
- 2 ATP - 2 NADH |
|
|
3 Fates of pyruvate
|
1.) in anaerobic conditions, fermentation to alcohol and yeast
2.) in aeobic, oxidized to Acetyl-CoA to be put in TCA 3.) in anaerobic, fermentation to lactate in vigorously contracting muscles * lactate can be used to reoxidize NADH |
|
|
Importance of phosphorylated intermediates
|
- are charged at pH 7, therefore can't leave the cell
- phosphorylation is a form of conservation of energy through the phosphate bond - energy derived from binding the phosphate grp to the active site helps lower the activation energy for the rxn |
|
|
How does lactose entery glycolysis?
|
- lactose turn into glucose and galactose (which can be turned in to glucose)
|
|
|
Conversion of galactose to glucose
|
- galactose phosphorylated at C-1 using 1 ATP
- add urindine diphosphate nucleotide - UPD-galactose converted to UPD-glucose by oxidation of C-4 by NAD+, then reduction of C-4 by NADH - UPD-glucose recycled to get Glucose 1-Phosphate - G1P converted to G6P by phophoglucomutase, which can then enter glycolysis |
|
|
How does glycogen enter glycolysis?
|
- breakdown of glycogen to G1P
- glycogen phosphorylase attacks nonreducing glycosidic link end - G1P turn to G6P to enter glycolysis |
|
|
How does sucrose enter glycolysis?
|
- sucrose can be broken down to glucose and fructose
- fructose can bypass and enter at F6P in glycolysis when catalyzed by hexokinase - fructose can turn into F1P then glyceraldehyde and dihydroxyacetone phosphate then to Glyceraldehyde 3-phosphate where it enters in glycolysis |
|
|
How does trehalose enter glycolysis?
|
- trehalose breaks down to glucose which can enter glycolysis
|
