Question | Answer |
glycolysis | an anaerobic sequence of reactions tha metabolize one molecule of glucose to two molecules of pyruvate |
glucogenesis | sequence of anaerobic reactions in which glucose is synthsized from noncarbohydrate percursors |
why would pyruvate be fermented in to lactate or ethanol instead of being completly oxidized in the citric acid cycle and electron transport chain. | in order to reduce the concentration of pyruvate under anaerobic conditions so that glycolysis is able to move forward. |
chap 14 but why does atp have a high phosphoryl tranfer potential in comparison to adp and amp | adp has greater resonance stability at the normal ph of body fluids 7 the triphospate unit of atp carries 4 negative charges which because of close proximity they repel each other and water can bind more effectivly to adp |
obligate anaerobes | organisms that cannot survive in the presence of o |
facultative anaerobes | orginisms that can function in the presence or absence of o |
list the three enzymes responible for the three reactions that take place in the first stage of glycolysis | hexokinase, phosphoglucose isomerase, phosphofructokinase. |
list the two enzymes responsible for the two reactions in the second stage of glycolysis | aldolase, triose phosphate isomerase |
list the five enzymes responsible for the five reactions that take place in the third stage of glycolysis. | glyceraldehyde 3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, pyruvate kinase. |
what is the function of hexokinase give the starting and end products of the reaction. where does it fit into glycogenesis | hexokinase uses atp to phosphorlate glucose as it diffuses into the cell so that it becomes trapped within the cell. reaction 1 |
describe the structure of glucose | five membered ring with the number 1 position occupied by o positions 2, 3 and 5 have hydroxy groups attached in the down position 4 has a hydroxy group in the up and position 6 has a methoxy group in the up |
describe the structure of glucose 6-phosphate (G-6P) | five membered ring with o in position 1 positions 2,3,5 have hydroxy groups in the down position 4 has a hydroxy group in the up and position 6 has a methoxy group with a phosphate attached |
kinase | an enzyme that catalyze the transfer of a phosphoryl grpup from atp require a divalent metal ion |
describe the conformational changes that take place when glucose binds to hexokinase | hexokinase has two lobes which move together when glucose binds encircling the molecule in nonpolar protine except the hydroxyl on carbon 6 which accepts the phosporyl if this conformation didmt happen h2o could act as the subtrate and act as an atpase |
what is the function of phosphoglucose isomerase. where does it fit into glycogenesis | isomeration of the aldose glucose 6-phosphate to the ketose fructose 6-phosphate. reaction 2 |
describe the structure of glucose 6-phosphate | furan ring with o in position 1 position 2 has a methoxy up and a hydroxyl down position 3 hydrxyl up position 4 hydroxyl down position 5 methoxy with a phosphoryl group up |
what is the function of phosphofructokinase. where does it fit into glycogenesis | uses one atp in the phosphorylation of fructose 6-phosphate to create 1,6-bisphosphate one of three reactions that regulate glycolysis. reaction 3 |
describe the structure of 1,6-bisphosphate | fruan ring with phosphorylated methoxy groups in positions 2 and 5 both up on position 2 there is also a hydroxyl group down on positions 3 and 4 hydroxyl groups up and down respectivly. |
what is the function of aldose? where does it fit into glycogenesis | splits fructose 1,6-bisphosphate into glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP). reaction 4 |
describe the structure of dihydroxyacetone (DHAP) | three carbon chain with a phosphate attached to carbon 1 a double bonded o on carbon 2 and a hydroxyl group on carbon 3. |
describe the structure of glyceraldehyde 3-phosphate (GAP) | three carbon chain with an aldehyde as carbon 1 a hydroxyl group attached to carbon 2 and a phosphate attached to carbon 3 |
what is the purpose of triose phosphate isomerase (TIM) and where does it fit into glycogenesis | isomerize dihydroxyacetone phosphate into glyceraldehyde 3-phosphate so that it can continue on the path of glycolysis. reaction 5 |
how does triose phosphate isomerase transform dihydroxyacetone phosphate into glyceraldehyde 3-phosphate | procedes through an enediol intermediate. glutamate 165 serves as an acid base catalyst pulling a hydrogen from carbon 1 and transfering it to carbon 2 histadine 95 donates a proton to carbon 2 to stabalize the negative charge page 432 |
what are some charateristics of tim | it is a kinetically perfect enzyme and it wuppresses a side reaction the decomposition of the enediol intermediate by preventing it from leaving the enzine by using a loop of ten residues as a lid until the isomerization is complete. |
list the ten enzymes involved in glycolysis in order of action | hexokinase, phosphoglucose isomerase, phosphofructokinase, aldolase, triose phosphate isomerase, gluceraldehyde 3-phosphate dehydrogenase, phosphoglucerate kinase, phosphoglycerate mutase, enolase and pyruvate kinase |