Glycolysis, TCA, Oxidative Phosphorylation

Stages of cellular respiration are

1. acetyl coA production (glycolysis)

2. acetyl coA oxidation (TCA)

3. electron transfer and oxidative phosphorylation (ETC)

Most of the major energy-generating pathways of cells eventually result in production of

acetyl coA (2C unit)

What is glucose converted to for storage?

glycogen

What is glucose oxidized to via the pentose phosphate pathway?

ribose 5-phosphate

What is glucose oxidized to via glycolysis?

pyruvate

3 fates of glucose

1. can be stored as a polysaccharide or as sucrose

2. oxidized to 3C compound pyruvate via glycolysis

3. oxidized to pentoses via pentose phosphate pathway

2 phases of glycolysis

preparatory phase

payoff phase

Step 1 of glycolysis

glucose uses a phosphate from ATP (turns ATP to ADP) and glucose is turned to glucose 6-phosphate

What converts glucose to glucose 6 phosphate?

hexokinase

Step 2 of glycolysis

Glucose 6-phosphate is converted to fructose 6-phosphate

What converts G6P to F6P?

phosphohexose isomerase

Step 3 of glycolysis

fructose 6-phosphate is converted to fructose 1,6-bisphosphate using another phsophate from ATP

What converts F6P to F1,6BP?

phosphofructokinase-1

Step 4 of glycolysis

Fructose-1,6-bisphosphate is cleaved into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate

What cleaves F1,6BP into its two products?

aldolase

Step 5 glycolysis

dihydroxyacetone is converted into another molecule of glyceraldehyde 3-phosphate

What converts dihydroxyacetone into G3P?

triose phosphate isomerase

What are the two priming reactions of glycolysis?

glucose to glucose 6-phosphate

fructose 6-phosphate to fructose 1,6-bisphosphate

Step 6 of glycolysis

glyceraldehyde-3-phosphate is oxidizied by NAD producing 1,3-bisphosphoglycerate

What is generated by step 6?

2 NADH + H+

What converts G3P into 1,3BPG?

glyceraldehyde 3-phosphate dehydrogenase

Step 6 involves...

phosphorylation and oxidation

Step 7 of glycolysis

1,3-bisphosphoglycerate is dephosphorylated to form 3-phosphoglycerate

What is formed in step 7?

2 ATP

What catalyzes the formation of 3-PG from 1,3-BPG?

phosphoglycerate kinase

What type of phosphorylation occurs in step 7?

substrate level

Step 8 of glycolysis

3-phosphogylcerate is converted to 2-phosphoglycerate

What converts 3-phosphoglycerate to 2-phosphoglycerate?

phosphoglycerate mutase

Step 9 of glycolysis

2-phosphoglycerate to phosphoenolpyruvate

What converts 2-phosphoglycerate to phosphoenolpyruvate?

enolase

Step 10 of glycolysis

phosphoenolpyruvate to pyruvate

What occurs in step 10?

substrate level phosphorylation

What converts phosphoenolpyruvate to pyruvate?

pyruvate kinase

In the prep phase of glycolysis, the energy of ATP is

invested

In what phase does energy gain come in glycolysis?

payoff phase

Preparatory phase

phosphorylation of glucose and its conversion to glyceraldehyde 3-phosphate

The priming stage of the prep phase involves...

the input of 2 molecules of ATP with the conversion of glucose into fructose 1,6-bisphosphate

The splitting stage of the prep phase does what?

splits the 6 C molecule of fructose 1,6-bisphosphate into 2 molecules of glyceraldehyde 3-phosphate

Payoff phase

oxidative conversion of glyceraldehyde 3-phosphate to pyruvate and the coupled formation of ATP and NADH

In the payoff oxidoreduction-phosphorylation stage ___________ molecules of glyceraldehyde 3-phosphate are converted into ___________ molecules of pyruvate with the production of __________ molecules of ATP

2, 2, 4

How many NADH are produced at the end of glycolysis?

2

The sum reaction for the 10 consecutive steps of glycolysis comes to the generation of...

2 pyruvate

2 NADH

2 ATP

at the expense of 1 glucose molecule

In the reaction of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate, what happens?

an aldehyde is oxidized to a carboxylic acid with the reduction of NAD+ to NADH

1,3-bisphosphoglycerate has a large _____________ free energy of hydrolysis, which enables it to do what?

negative, participate in a subsequent reaction that yields ATP

How many molecules of ATP are invested in the priming stage?

2

The glyceraldehyde 3-phosphate dehydrogenase- phosphoglycerate kinase system is an example of

substrate level phosphorylation

Substrate level phosphorylation

The formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism

Enolase catalyzes the elimination of

water from 2-phosphoglycerate to form phosphoenolpyruvate

Pyruvate kinase accomplishes...

substrate level phosphorylation by the synthesis of ATP with the conversion of the high-energy compound PEP into pyruvate

The reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase requires ________ and produces...

NAD+, NADH

Because the cytosol of cells only has a limited amount of NAD+, it is imperative for continuous glycolytic activity that the ____________ be converted back to ______________

NADH, NAD+

The last step of the glycolytic pathway is

oxidoreduction reaction catalyzed by lactate dehydrogenase

What does lactate dehydrogenase do?

converts pyruvate to lactate, yielding NAD+

oxidizes NADH to NAD+

NADH generated by glyceraldehyde 3-phosphate dehydrogenase is converted back into NAD+ by

lactate dehydrogenase

Cells under what condition require lactate dehydrogenase for regeneration of cytosolic NAD+?

anaerobic conditions

What are the regulatory enzymes of the glycolytic pathway commonly considered to be?

hexokinase

phosphofructokinase-1

pyruvate kinase

What is the rate limiting enzyme of glycolysis?

Phosphofructokinase-1 (PFK-1)

What is the most important regulatory site of glycolysis in most tissues?

PFK-1

Most important negative allosteric effectors of glycolysis

citrate, ATP, hydride ions (low pH)

Most important positive allosteric effectors of glycolysis

AMP, fructose 2,6-bisphosphate, and Pi

Glycolysis is the process by which glucose is ___________ into two molecules of pyruvate, with energy conserved as ______________

oxidized, NADH and ATP

In the preparatory phase, ATP is invested to convert ________________ to _________________. _______________ is then broken down into two molecules of _________________

glucose, fructose 1,6-bisphosphate, fructose 1,6-bisphosphate, glyceraldehyde 3-phosphate

In the payoff phase, each of the two molecules of _________________ undergoes _______________. The energy of this _______________ is conserved in the formation of _______________

G3P, oxidation, oxidation, NADH and ATP

Pyruvate dehydrogenase complex

converts pyruvate to acetyl CoA

Conversion of pyruvate to acetyl CoA is what type of reaction?

oxidative decarboxylation

Pyruvate must enter the ___________ to enter the TCA cycle

mitochondria

Oxidative decarboxylation of pyruvate is catalyzed by the

pyruvate dehydrogenase complex

How many enzymes make up the pyruvate dehydrogenase complex?

3

How many coenzymes are required in the pyruvate dehydrogenase complex?

5

In the TCA cycle, pyruvate from glycolysis is ____________ to _____________

oxidatively decarboxylated, acetate

What is acetate degraded to in the TCA cycle?

CO2

The NADH from the TCA cycle goes on to make more _____________ where?

ATP, ETC and oxidative phosphorylation

Oxidative decarboxylation of isocitrate yields

a-ketoglutarate

Isocitrate dehydrogenase is a link to the ETC pathway because it makes

NADH

Acetyl coA is converted to what in TCA cycle in step 1?

citrate

What converts acetyl-CoA to citrate?

citrate synthase

What is put in and generated in the step that turns acetyl coA to citrate?

water put in, CoA-SH generated

Citrate is next converted to

isocitrate

What converts citrate to isocitrate?

aconitase

Isocitrate next yields

CO2, NADH, and a-ketoglutarate

What converts isocitrate to a-ketoglutarate?

isocitrate dehydrogenase

a-ketoglutarate is converted into

Succinyl CoA and CO2 and NADH

What converts a-ketoglutarate into succinyl-CoA?

a-ketoglutarate dehydrogenase complex

Succinyl CoA is converted to

succinate + GTP

What converts succinyl CoA to succinate?

succinyl-CoA synthetase

Succinate is _________________ to form ______________

dehydrogenated, fumarate

What converts succinate to fumarate?

succinate dehydrogenase

Succinate dehydrogenase is seen where?

TCA cycle and ETC

What is yielded when succinate is dehydrogenated to fumarate?

FADH2

Fumarate is hydrated to

malate

What converts fumarate to malate?

fumarase

Malate is _______ to form ______________

dehydrogenated, oxaloacetate

Converts malate to oxaloacetate

malate dehydrogenase

What does oxaloacetate make?

acetyl CoA

Pyruvate, the product of glycolysis, is converted to ____________, the starting material for the TCA cycle, by what multienzyme complex?

acetyl-CoA, pyruvate dehydrogenase complex

The TCA cycle is a central ____________ pathway in which compounds derived from the breakdown of _______________ are oxidized to _________________

catabolic, carbs, fats, and proteins, CO2

Acetyl-CoA enters the TCA cycle through its condensation with _____________ to form ________________

oxaloacetate, citrate

The TCA cycle converts ____________ to ______________ and releases __________ CO2

citrate, oxaloacetate, 2 CO2

For each acetyl-CoA oxidized, the energy gain consists of _______ NADH, __________ FADH2, and ____________ GTP

3, 1, 1

Steps that generate NADH

isocitrate dehydrogenase

a-ketoglutarate dehydrogenase

malate dehydrogenase