Glycolysis and TCA Cycle - QUIZ #1 Macronutrient Biochemistry - KENT STATE UNIVERSITY

what is the first step of glycolysis?

Glycosylation of glucose; glucose is phosphorylated becoming Glucose-6-phosphate; irreversible reaction

what enzyme is needed to phosphorylate glucose to glucose-6-phosphate?

hexokinase; this step of phosphorylation also requires ATP --> ADP and Mg2+

what is the second step of glycolysis?

isomerization of glucose-6-phosphate; this is where the carbonyl oxygen of glc-6P is shifted from C1 --> C2 via the enzyme phosphoglucose isomerase; this turns glucose-6-phosphate into fructose-6-phosphate; reversible reaction

what enzyme is required in the isomerization of glucose-6-phosphate?

phosphoglucose isomerase; this is what allows the transformation of G6P --> F6P

what is the third step of glycolysis?

phosphorylation of fructose-6-phosphate; this is where PFK-1 phosphorylation of C1 turns Fruc-6P into Fruc-1,6-bisphosphate; irreversible reaction

what enzyme is required in the phosphorylation of Fructose-6-phosphate?

phosphofructokinase-1; this step also requires ATP --> ADP and Mg2+

what is the fourth step of glycolysis?

cleavage of Fruc-1,6-bisphosphate (splitting phase); fruc-1,6-bisphosphate is split by aldolase to become DHAP (dihydroxyacetone phosphate) and G3P (Glyceraldehyde-3-phosphate); reversible reaction

what enzyme is used in cleavage of fructose-1,6-bisphosphate to DHAP and G3P?

aldolase; this conversion also utilizes the enzyme triosephosphate isomerase to convert DHAP to G3P, this is because DHAP cannot enter the second phase of glycolysis and needs to convert into G3P; aldolase alongside triosephosphate isomerase ultimately allow for utilization of two molecules of G3P

what is the fifth step of glycolysis?

isomerization of dihydroxyacetone phosphate; this isomerization requires the enzyme triosephosphate isomerase to become glyceraldehyde-3-phosphate; reversible reaction

what is the sixth step of glycolysis?

oxidation of glyceraldehyde-3-phosphate (2); this is the first E yielding step converting G3P (2) into 1,3-bisphosphoglycerate (2) via G3P dehydrogenase, this step requires 2 Pi as well as 2 NAD+ to become 2 NADH + H+; reversible reaction - first redox reaction of glycolysis, NADH must be reoxidized to NAD+ for glycolysis to continue

what is the enzyme required in the oxidation of glyceraldehyde-3-phosphate (2) to 1,3-bisphosphoglycerate (2)?

glyceraldehyde-3-phosphate dehydrogenase (G3P DH); this reaction also requires 2 NAD+ and 2 Pi to provide energy in the form of 2 NADH + H+

what is the seventh step of glycolysis?

formation of 3-phosphoglycerate producing ATP; phosphoglycerate kinase enzyme transfers phosphate groups from 1,3-BPG (2) to ADP (2) forming ATP (2) and 3-phosphoglycerate (2); unlike most other kinases this reaction IS physiologically reversible, substrate-level-phosphorylation, ATP is formed at the expense of a substrate, first ATP synthesizing rxn of glycolysis

what enzyme is required in the formation of 3-phosphoglycerate producing ATP?

1,3-BPG kinase (phosphoglycerate kinase); this reaction requires Mg2+

what is the eighth step of glycolysis?

shift of the phosphate group from C3 --> C2; 3PG (2) becomes 2PG (2) due to the action of the enzyme 3PG mutase, 3PG mutase (phosphoglycerate mutase) is applied to enzymes that catalyze migration of a functional group within a molecule; reversible reaction

what is the enzyme utilized in the shift of the phosphate group from C3 --> C2 which changes 3PG to 2PG?

phosphoglycerate mutase, or 3PG mutase; mutases are used to catalyze the migration of a functional group within its own molecule

what is the ninth step of glycolysis?

dehydration of 2-phosphoglycerate (2) to phosphoenolpyruvate (2); 2PG (2) is dehydrated to 2 PEP (2) via enzyme enolase releasing H2O (2)

what is the enzyme involved in dehydration of 2-phosphoglycerate?

enolase; enolase creates PEP (2) with the release of H2O (2) from 2PG (2)

what is the tenth step of glycolysis?

formation of pyruvate producing ATP; PEP (2) provides phosphate groups for the phosphorylation of ADP (2) --> ATP (2), this is the second ATP synthesizing reaction of glycolysis and the third and final irreversible reaction; in this step, pyruvate kinase mediates the transfer of a PO3- group from PEP (2) to ADP (2) with the generation of ATP

what is the enzyme involved in the formation of pyruvate producing ATP?

PEP kinase (pyruvate kinase) this kinase phosphorylates ADP (2) to ATP (2) providing E, this reaction requires Mg2+ and K+ to take place

what is the TCA cycle?

final pathway where the metabolism of CHO, AAs, and FAs converge (Acetyl CoA); oxidation provides E for the production of the majority of ATP; totally occurs in mitochondria; TCA = aerobic pathway requiring O2

How does pyruvate interact with TCA cycle?

pyruvate is converted to Acetyl CoA with the introduction of CoA and NAD+ with the release of CO2 and NADH + H+ as E

what is the first reaction of the TCA cycle?

the synthesis of citrate (condensation reaction, 1st irreversible reaction); citrate synthase catalyzes the condensation reaction of Acetyl-CoA and Oxaloacetate as well as the introduction of H2O yielding the release of CoA-SH to ultimately form citrate

what is the enzyme involved in the synthesis of citrate?

citrate synthase; this enzyme allows for the condensation reaction of Acetyl CoA and oxaloacetate to become citrate

what is the second step of the TCA cycle?

isomerization of citrate; citrate becomes isocitrate via the enzyme aconitase which catalyzes this conversion

what is the enzyme involved in the isomerization of citrate?

aconitase; this enzyme catalyzes the conversion of citrate to isocitrate

what is the third step of the TCA cycle?

oxidative decarboxylation of isocitrate (2nd irreversible reaction); isocitrate dehydrogenase is utilized to catalyze the conversion of isocitrate to alpha-ketoglutarate, this reaction releases CO2 and reduces NAD+ to NADH + H+

what is the enzyme used in the oxidative decarboxylation of isocitrate?

isocitrate dehydrogenase; this enzyme catalyzes the conversion of isocitrate to alpha-ketoglutarate

what is the fourth step of the TCA cycle?

oxidative decarboxylation of alpha-ketoglutarate (3rd irreversible reaction); alpha-KG DH catalyzes the conversion of alpha-KG to succinyl CoA alongside the introduction of CoA-SH, and NAD+ which is reduced to NADH + H+, while CO2 is released

what is the name of the enzyme used in the oxidative decarboxylation of alpha-ketoglutarate?

alpha-KG dehydrogenase, this enzyme is used to catalyze the conversion of Alpha-KG to Succinyl CoA

what is the fifth step of the TCA cycle?

cleavage of Succinyl CoA; in this step, succinyl CoA synthetase releases CoA-SH as well as allows for the conversion of GDP + Pi to GTP which ultimately results in the formation of ATP from ADP succinyl CoA becomes succinate in the end.

what is the enzyme used in the cleavage of succinyl CoA?

succinyl CoA synthetase, this enzyme catalyzes the conversion of succinyl CoA to succinate

what is the sixth step of the TCA cycle?

oxidation of succinate; succinate dehydrogenase is utilized to catalyze the conversion of succinate to fumarate with the reduction of FAD to FADH2

what is the enzyme utilized in the oxidation of succinate?

succinate dehydrogenase, this enzyme catalyzes the conversion of succinate to fumarate with the reduction of FAD to FADH2

what is special about succinate dehydrogenase?

only enzyme of TCA cycle that is embedded in the inner mitochondrial membrane & is a part of the ETC

what is the seventh step in the TCA cycle?

hydration of fumarate; fumarase utilizes a molecule of H2O catalyzing the conversion of fumarate to malate

what is the enzyme used in the hydration of fumarate?

fumarase, this enzyme is utilized to draw in a molecule of water catalyzing the conversion of fumarate to malate

what is the eighth step of the TCA cycle?

oxidation of malate; malate dehydrogenase is utilized to catalyze the conversion of malate to oxaloacetate while simultaneously reducing NAD+ to NADH + H+

what is the enzyme utilized in the oxidation of malate?

malate dehydrogenase, this enzyme is utilized to catalyze the conversion of malate to oxaloacetate, OAA goes on through the cycle combining with Acetyl CoA to remake citrate and begin the process over again