Biochem exam ch 9-10

What are the 10 reactions of glycolysis

What are the 10 reactions of glycolysis

1. Glucose —hexokinase(ATP)—> Glucose-6-P

2. Glucose-6-P —phosphoglucoisomerase—> Fructose-6-P

3. Fructose-6-P —phosphofructokinase-1(ATP)—> Fructose-1,6-BP

4. Fructose-1,6-BP —Aldolase—> Dihydroxyacetone-P

5. Dihydroxyacetone-P —Triose phosphate isomerase—> Enediol intermediate

6. Glyceraldehyde-3-P —Glyceraldehyde-3-P dehydrogenase(NAD+ → NADH)—> 1,3-BPG

7. 1,3-BPG —Phosphoglycerate kinase (ATP released)—> 3-phosphoglycerate

8. 3-phosphoglycerate —phosphoglycerate mutase—> 2-phosphoglycerate

9. 2-phosphoglycerate —Enolase (water released)—> phosphoenolpyruvate

10. phosphoenolpyruvate —Pyruvate kinase (ATP released)—> pyruvate

what is the rate limiting step in glycolysis

reaction #3 (phosphofructokinase-1)

Rxn #1 in glycolysis (Hexokinase) is what kind of reaction

phosphorylation reaction

Rxn #1 in glycolysis (Hexokinase) utilizes what energy source

ATP

Rxn #1 in glycolysis (Hexokinase) requires what for the reaction to proceed

Mg2+

Rxn #2 in glycolysis (phosphoglucoisomerase) is what type of reaction

isomerization

Rxn #3 in glycolysis (Phosphofructokinase-1) is what type of reaction

phosphorylation

Rxn #3 in glycolysis (Phosphofructokinase-1) utilizes what energy source

ATP

Rxn #4 in glycolysis (Aldolase) is what type of reaction

Cleavage

From an Aldolase reaction (#4 of glycolysis) there are two products, what are they and what are they each used for

Glyceraldehyde-3-P is the main thing that goes on in the glycolysis cycle (can also form an intermediate used in side reactions)

Dihydroxyacetone-P is not used any further in glycolysis but can form an intermediate for side reactions

Rxn #5 in glycolysis (Triose Phosphate Isomerase) is what type of reaction

Isomerization

What 2 groups of reactions are in glycolysis and what are they

Divided into ATP investment and ATP generation

ATP investment are steps 1-5

ATP generation are steps 6-10

Rxn #6 in glycolysis (Glyceraldehyde-3-P dehydrogenase) is what type of reaction

phosphoryl group transfer

Rxn #6 in glycolysis (Glyceraldehyde-3-phosphate dehydrogenase) produces what

NAD+ → NADH and H+

Rxn #7 in glycolysis (Phosphoglycerate Kinase) is what type of reaction

Substrate-level phosphorylation

Rxn #7 in glycolysis (Phosphoglycerate Kinase) produces what

2x ATP

What is the side reaction in RBC that can occur during and result in rxn #7 in glycolysis

1,3-BPG —BPG mutase—> 2,3-BPG

2,3-BPG —2,3-BPG phosphatase (inorganic phosphate leaves)—>3-phosphoglycerate

What is the purpose of the side rxn in RBC instead of glycolysis rxn #7

The side rxn puts hemoglobin in the T-state to maximize O2 release from hemoglobin

Rxn #8 in glycolysis (Phosphoglycerate Mutase) is what type of reaction

Phosphoryl shift

Rxn #9 in glycolysis (Enolase) is what type of reaction

Dehydration

What is the highest energy molecule in glycolysis

Phosphoenolpyruvate (PEP)

Rxn #10 in glycolysis (Pyruvate Kinase) is what type of reaction

Substrate-level phosphorylation

Rxn #10 in glycolysis (Pyruvate Kinase) produces what

2x ATP

When Sucrose is the starting material, how does it get converted to aid in glycolysis

1. Sucrose is changed to Fructose by Sucrase enzyme

2. Fructose can either

   • utilize ATP and Hexokinase (in muscle) to create Fructose-6-P to continue in the glycolysis cycle

   • utilize ATP and Fructokinase (in liver) to create Fructose-1-P.

     • Fructose-1-P can utilize Fructose-1-P aldolase (aldolase B) to form Glyceraldehyde and Dihydroxyaceton-P which can be converted to Glyceraldehyde-3-P to continue in the glycolysis cycle

Which mechanism is preferred for Fructose to aid in glycolysis

Prefers utilizing ATP and Fructokinase to form Fructose-1-P which then utilizes Fructose-1-P aldolase (aldolase B) to form Glyceraldehyde and Dihydroxyacetone-P which can be converted to Glyceraldehyde-6-P to continue in glycolysis

Fructose utilizing ATP and hexokinase to form Fructose-6-P is not preferred

When Lactose is the starting material, how is it converted to aid in glycolysis

Lactose is either:

• Converted to glucose to continue through glycolysis

• converted to Galactose through lactase then Galactose utilizes ATP and Galactokinase to yield Galactose-1-P which is converted to Glucose-1-P by UDP-glucose and UDP-galactose before being converted from Glucose-1-P to Glucose-6-P to continue through glycolysis

When Maltose is the starting material, how does it aid in glycolysis

Maltose is converted to Glucose utilizing Maltase and Glucose starts glycolysis

When triglycerides are the starting material, how is this converted to aid in glycolysis

Triglycerides can either:

• Be converted to Acetyl-CoA by Lipase 1, 2, or 3 converting them to fatty acids to undergo fatty acid oxidation yielding Acetyl-CoA

• Triglycerides can be converted to Glycerol by Lipase 1, 2, and 3. The Glycerol can utilize ATP and Glycerol kinase to yield Glycerol-3-P which can be converted to dihydroxyacetone-P by FAD and Glycerol-3-P dehydrogenase

What are the four steps of Galactose metabolism

1. Galactose —Galactokinase(ATP)—> Galactose-1-P

2. Galactose-1-P —Galactose-1-P uridylyltransferase and UDP-glucose—> Glucose-1-P and UDP-galactose

3. Glucose-1-P —Phosphoglucomutase—> Glucose-6-P (continues to the glycolytic pathway)

4. UDP-galactose —UDP-galactose 4-epimerase—> UDP-glucose

How is glycogen formed as a glycolytic intermediate (anabolic pathway)

Glucose is converted to Glucose-1-P and then to Glycogen

How are nucleotides formed as a glycolytic intermediate (anabolic pathway)

Glucose is converted to Pentose phosphates which can be converted to nucleotides

How are Glycolipids and Glycoproteins formed as a glycolytic intermediate (anabolic pathway)

Fructose-6-P is converted to amino sugars which can be broken down into glycolipids and glycoproteins

How does glucose promote the Pentose phosphate pathway

Glucose is converted to pentose phosphates, which utilize NADP+ → NADPH to activate the Pentose phosphate pathway

How does 1,3-BPG play a role in oxygen transport regulation

1,3-BPG can be converted to 2,3-BPG which regulates oxygen transport

How can Pyruvate be converted to Asparagine and Pyrimidines

Pyruvate can be converted to aspartate which can be broken down to Asparagine and pyrimidines

What type of metabolism happens in Aerobic conditions

ATP production (citrate cycle and electron transport chain)

What type of metabolism happens in Anaerobic conditions

production of lactate

ethanol production

Under what conditions does glycolysis happen

Anaerobic conditions

Under what conditions does fermentation happen

Anaerobic

Under what conditions is Pyruvate turned to Lactate via lactate dehydrogenase

Anaerobic

Under what conditions does electron transport happen

Aerobic metabolism

Under what conditions does oxidative phosphorylation happen

Aerobic metabolism

Under what conditions does the citrate cycle happen

Aerobic metabolism

Where is NAD+ regenerated

in the cytoplasm

What is required in order to maintain flux through GAPDH (Glyceraldehyde dehydrogenase)

NAD+

A lactate dehydrogenase deficiency which enzyme is inadequate and what levels are inadequate

Lactate dehydrogenase is not functional and NAD+ are inadequate

The more sugar alcohol is, what happens to the ETOH concentration

more sugar has greater ETOH content

What is the primary function of the citrate cycle

To oxidize acetyl CoA

What are the end results of the citrate cycle

Transfer of eight electrons

Generates 3x NADH

Generates 1x FADH2

Generates 1x GTP

what group do the reactions in the citrate cycle fall into

redox reactions

How many ATP’s correlate to 1 GTP and how

1 GTP = 1 ATP through work

How many ATP’s does 1 FADH2 yield and how

~1.5 ATP = 1 FADH2 and 2 electrons through electron transport system and ATP synthase

How many ATP’s does 1 NADH yield and how

1 NADH and 2 electrons = ~2.5 ATP

Citrate cycle yields 3 NADH and 6 electrons = ~7.5 ATP

What are the three enzymes involved with pyruvate dehydrogenase

Pyruvate dehydrogenase component

Dihydrolipoyl transacetylase

Dihydrolipoyl dehydrogenase

What do Dihydrolipoyl transacetylase and Dihydrolipoyl dehydrogenase do generally

Aid in regeneration of coenzymes

What are the five coenzymes involved in pyruvate dehydrogenase

NAD+

FAD

CoA

TPP (Thiamine pyrophosphate)

Alpha-lipoic acid

Where is CoA derived from

Vitamin B5

How is Coenzyme A turned into Acetyl coenzyme A

Acetyl-dihydrolipoamide and Pyruvate dehydrogenase switches the reactive thiol group to an acetyl group and dihydrolipoamide is released

where is TPP (Thiamine pyrophosphate) derived from

Vitamin B1

TPP (thiamine pyrophosphate) and ATP are required for what

Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase

What does alpha-lipoic acid provide that participates in redox reactions

provides a reactive disulfide that participates in redox reactions

What does pyruvate dehydrogenase catalyze the conversion of

pyruvate to acetyl coA

Pyruvate dehydrogenase catalyzes a reaction that transitions from what to what

Transition from glycolysis to the citrate cycle

Pyruvate dehydrogenase is regulated by what

phosphorylation, NADH, ATP, and acetyl-CoA levels

The active form of PDH can be inactivated by pyruvate dehydrogenase kinase what stimulates pyruvate dehydrogenase kinase

NADH, acetyl-CoA, and ATP

The active form of PDH can be inactivated by pyruvate dehydrogenase kinase, what inactivates pyruvate dehydrogenase kinase

NAD+, CoA, ADP, and Ca2+

The inactive form of PDH can be activated by pyruvate dehydrogenase phosphatase-1, what activates pyruvate dehydrogenase kinase

Ca2+

What does pyruvate dehydrogenase kinase require to inactivate active PDH

ATP

What does pyruvate dehydrogenase phosphatase-1 need to activate inactive PDH

H20

what energy state are you in when ongoing the citric acid cycle or glycolysis

Low energy state (you need to generate ATP)

What irreversibly blocks catalytic activity of lipoamine-containing enzymes

Arsenic

What type of environment is the citrate cycle in

Aerobic pathway

What do standard reduction potentials indicate

spontaneity

Positive is spontaneous (opposite of G)

Reductant

better at being oxidized, reducing agent

Oxidant

better at being reduced, oxidizing agent

What are the 8 reactions in the citrate cycle

1. Oxaloacetate + Acetyl-CoA —citrate synthase (H20→CoA)—> citrate

2. Citrate —Aconitase(H2O leaves)—> cis-Aconitate —Aconitase(+H2O)—> isocitrate

3. Isocitrate —Isocitrate dehydrogenase (NAD+ → NADH + H+) or (NADP+ → NADPH + H+)—> Oxalosuccinate —isocitrate dehydrogenase (CO2 leaves and H+ enters)—> Alpha-Ketoglutarate

4. Alpha-Ketoglutarate —Alpha-Ketoglutarate dehydrogenase complex (E1: TPP→CO2, E2: CoA in and enzyme Lipoamide needed, E3: NAD+ → NADH + H+ and FAD needed)—> Succinyl-CoA

5. Succinyl-CoA —(Pi→CoA)—(GDP→GTP)—> Succinate

6. Succinate —succinate dehydrogenase—(FAD→FADH2)—> Fumarate

7. Fumarate —Fumerase—(OH- in)—> Carbanion intermediate —Fumarase—(H+ in)—> Malate

8. Malate —Malate dehydrogenase—(NAD+→NADH + H+)—> Oxaloacetate

Rxn #1 of citrate cycle (Citrate synthase) is what type of reaction

condensation

Rxn #1 of citrate cycle (citrate synthase) is it favorable

yes

Rxn #2 in the citrate cycle (aconitase) can be categorized as what types of reaction

Isomerization of citrate

and

Dehydration-hydration

What type of enzyme is aconitase (rxn #2 of citrate cycle)

Fe-S cluster enzyme

Rxn #3 in the citrate cycle (isocitrate dehydrogenase) is what type of reaction

Oxidative decarboxylation

Rxn #3 of citrate cycle (Isocitrate dehydrogenase) produces what

NADH

Rxn #4 in the citrate cycle (Alpha-ketoglutarate dehydrogenase) is what type of reaction

Oxidative decarboxylation

What makes up alpha-ketoglutarate dehydrogenase

multiple subunits

Rxn #4 in the citrate cycle (Alpha-ketoglutarate dehydrogenase) produces what

NADH

Rxn #5 in the citrate cycle (Succinyl-CoA synthetase) is what type of reaction

substrate level phosphorylation

Rxn #5 in the citrate cycle (Succinyl-CoA synthetase) produces what

GTP

Rxn #6 in the citrate cycle (Succinate dehydrogenase) is what type of reaction

redox reaction

Rxn #6 in the citrate cycle (succinate dehydrogenase) produces what

FADH2

Rxn #7 in the citrate cycle (Fumarase) is what type of reaction

hydration

Rxn #7 in the citrate cycle (Fumerase) is what

stereospecific (L-isomer)

Rxn #8 in the citrate cycle (Malate dehydrogenase) is what type of reaction

Oxidation

Rxn #8 in the citrate cycle (Malate dehydrogenase) generates what

NADH

Which reaction in the citrate cycle favors the reverse rxn instead of the forward

Rxn #8 in the citrate cycle (malate dehydrogenase)

What are the three main regulatory enzymes of the citrate cycle

Citrate synthase (rxn #1)

Isocitrate dehydrogenase (rxn #3)

Alpha-ketoglutarate dehydrogenase (rxn #4)

A key control point of the citrate cycle is pyruvate, what two reactions can pyruvate initiate

Pyruvate to Acetyl-CoA with pyruvate dehydrogenase (CO2 released)

Pyruvate to oxaloacetate with pyruvate carboxylase (ATP + HCO3- to ADP)

A key control point of the citrate cycle is Acetyl-CoA, what reaction does this initiate

Acetyl-CoA to citrate with citrate synthase

A key control point of the citrate cycle is Isocitrate, what reaction does this initiate

Isocitrate to alpha-ketoglutarate with isocitrate dehydrogenase

A key control point of the citrate cycle is alpha-ketoglutarate, what reaction does this initiate

Alpha-ketoglutarate to Succinyl-CoA with alpha-ketoglutarate dehydrogenase

What activates pyruvate dehydrogenase

NAD+, CoA, ADP, Ca2+