Exercise Biochem Wk 10-12

What is the whole purpose of metabolism?

To produce ATP!

What is oxidation?

Loss of electron OR interaction of oxygen (O2) with other substances

T or F: The oxidation of glucose involves reactions with oxygen through all stages.

False. Oxidation of glucose is an oxygen-requiring process BUT not all stages involve reactions with oxygen.

T or F: Glucose oxidation is the breakdown of glucose to release energy as ATP.

True

What's the input of glucose oxidation?

6 Oxygen (O2) + Glucose (C6H12O6) + 38 ADP

What's the output of Glucose Oxidation?

6 Carbon dioxide (CO2) + 6 Water (H2O) + 38 ATP

What are the 4 phases of Glucose Oxidation?

1. Glycolysis
2. Pyruvate Dehydrogenase Rx (PDH)
3. Citric Acid Cycle (CAC)
4. Electron Chain Transport (ETC)

Where does glycolysis occur in the cell?

In the cytoplasm

Where does pyruvate hydrogenase occur in the cell?

From cytoplasm into the mitochondria (transports pyruvate into mitochondria from cytoplasm)

Where does the citric acid cycle occur in the cell?

Mitochondria - mitochondrial matrix

Where does the electron transport chain occur in the cell?

Mitochondria - inner mitochondrial membrane

T or F: The mitochondria has a double membrane.

True. Which makes it very strong!

T or F: Glucose can diffuse directly into the cell.

False. It's is a polar molecule so it requires a transporter to enter the cell.

What are the 2 transport mechanisms for glucose diffusion?

Facilitated transport via transporters and co-transport with sodium.

What is facilitated glucose transport?

A glucose transporting mechanism mediated by a family of at least five glucose (GLUT-1 to GLUT-5)

What is GLUT-4 and what does it do?

GLUT-4 is a dynamic protein transporter located in the cytoplasm that TRANSLOCATES (moves) to the cell membrane when glucose disposal from the blood is required.

When is glucose disposal required?

After a meal

What are the 7 steps of glucose disposal after a meal?

What triggers the translocation of GLUT-4?

Insulin and muscle contraction

T or F: Type I diabetes is insulin resistant.

False. Type I diabetes doesn't produce insulin and type II diabetes is insulin resistant. Both lead to increased levels of blood-glucose.

T or F: Exercise activates GLUT-4 and helps maintain blood glucose.

True!

When bonds are broken and phosphate is released, how much energy (kJ) is released into the cell for mechanical work?

-30.5kJ

What are hydration/dehydration reactions?

Addition/removal of H2O
Enzyme: hydratase/dehydratase

What are oxidation/reduction reactions?

Loss/gain of electrons
Enzymes: dehydrogenase enzymes; NAD+ and FAD coenzymes

What are phosphorylation/dephosphorylation reactions?

Loss/gain of inorganic phosphate
Enzymes: Kinase/Phosphatase enzymes

What's a simplified overview of the glycolysis process? (6=2x3)

6 carbon glucose is split into 2 molecules of 3 carbon pyruvate (6=2x3). So 1 glucose = 2 pyruvate

What's a simplified overview of the glycolysis pathway? 2:2=2:2:2

1- 2 ADP are consumed
2- 2 NAD+ are consumed
3- 2 net ATP are produced
4- 2 NADH are produced
5- 2 pyruvate are produced

T or F: There are 7 enzymatic steps in glycolysis.

False. There are 10 dude.

What are the 2 main stages of glycolysis?

Preparatory (steps 1-5) and pay-off (steps 6-10)

T or F: The product of one step becomes the reactant of the next.

True.

A large negative delta F usually means a _________ _________ reaction.

spontaneous; irreversible

T or F: Hexokinase is in the liver and glucokinase in every other tissue.

False. Glucokinase in liver; Hexokinase in every other tissue

T or F: Both dietary glucose AND glucose from glycogen breakdown into glycolysis and there first product is glucose-6-phosphate.

TRUE!!!

What's the biochemical process here and the enzyme required?

Isomerization and (phosphohexose) isomerase

A small positive delta G is usually a _________ __________ reaction.

spontaneous; reversible

When ATP/ADP is involved in a step, the enzyme required is always __________.

Kinase

What's a possible enzyme name for this step? Why?

Fructose-6-phosphate kinase because the enzyme is named with substrate followed by enzyme AND in the direction of ATP production.

What is the slowest enzyme of glycolysis and why?

Phosphofructokinase (PFK) in Step 3 because it has the largest Km, but exercise can decrease the Km.

T or F: Having a large Km means having a high attraction for its substrate, meaning it needs less substrate to get to 1/2 Vmax.

FALSE. Large Km = LOW attraction for substrate = MORE substrate needed to get to 1/2 Vmax.

Fill this out. (Step 4 glycolysis)

What is a common name for lyase?

aldolase

A large positive delta G is usually a _________ _________.

non-spontaneous; irreversible

Step 4 of glycolysis should be irreversible but is reversible, why?

Delta G is determined in laboratory via in-vivo conditions which can have varying cellular concentrations in a matter of seconds. Sooo human error.

T or F: There is no production of ATP in the Preparatory phase.

True. ATP is consumed and not yet produced.

What are 3 enzyme naming rules to remember?

1 - Oxidation reaction is always prioritized
2- Enzyme is always named in the direction of ATP being added to the reaction (kinase)
3- Enzyme is always named in direction of dehydrogenation/oxidation of reaction (dehydrogenase)

Step 7 is supposed to be spontaneous and irreversible but is reversible, why?

Because the reverse rx will consume ATP, so delta G will be coupled to the hydrolysis of ATP. This means that instead of having a delta G OF +18.9kj/mol it will be -11.6kj/mol since hydrolysis of ATP is -30.5kJ/mol.

What enzyme is required in this step? Why?

Mutase because it's in isomerization but specifically an internal transfer of phosphatase position.

T or F: NADH doesn't need oxygen to get converted back to NAD+.

False. NADH needs oxygen to convert back to NAD+

Since there is an imbalance in ratio of NADH/NAD+, this forces pyruvate to be converted to ___________.

lactate

What conditions stop energy production at the stage of glycolysis?

Anaerobic

Hydrogenation is also knows as...

reduction (gain of H+)

What are the 3 irreversible steps of glycolysis?

Step 1 (hexokinase) Step 3 (PFK) and Step 10 (pyruvate kinase)

T or F: Glycolysis is the only process of glucose oxidation that doesn't need oxygen.

True. But every other process does so if oxygen isn't available then glucose oxidation stops at glycolysis.

What are the 2 main benefits of lactate?

1- Regeneration of NAD+ so glycolysis can continue
2- Can be converted back to glucose (glucogenesis) as a substrate so it's a valuable energy source

T or F: Lactic acid is the primary cause of fatigue during max exercise.

False! Lactate formation has little change to pH/acidity of cell so it's not the primary cause fatigue during exercise.

What is the rate limiting of glycolysis

Phospofructokinase (PFK)

T or F: The glucose from glycogen enter glycolysis at step 4.

False. Enters at step 2

What is the actual enzyme name for a reaction of glycolysis when ADP is added as a substrate and ATP is a product?

Kinase

The overall ΔG of glycolysis is...

-85kJ/mol so it's highly exergonic

Pyruvate is found in the body as an ______, carrying a negative charge on oxygen following dissociation of a hydrogen atom.

anion

Pyruvate can be converted into 4 things: alanine and oxoacetate if levels are _____, to lactate in _______ glycolysis and to acetyl-coA in _________ glycolysis.

low; anaerobic; aerobic

1 pyruvate generate ___ NADH.

1

The citric acid cycle (CAC) is used to generate energy through the oxidation of _____________.

Acetyl CoA

T or F: CAC is a dispensable part of aerobic respiration amongst plants, animals, and fungi.

False. It's INDISPENSABLE

What is decarboxylation?

Loss of carboxylic acid group (decarboxylase enzymes)

What is GTP in the CAC?

Guanine Adenosine Trisphosphate

T or F: There are 2 citric acid cycles per glucose.

True.

1 CAC generates: ___ GTP, ___ NADH, and ____ FADH2

1;3;1

What are the 3 highly exergonic reactions in CAC?

Reactions 1,4, and 5

What is the overall delta G of CAC?

-40kJ/mol

T or F: CAC only operates in one direction.

True

Per glucose molecule, the yield of CAC is ____ GTP, _____ NADH, and _____ FADH2

2;6;2 (because 1 cycle 1;3;1 goes twice per glucose)

T or F: The fate of pyruvate is determined by three main factors, the need for ATP (energy status of the cell), NAD+, and glucose.

True

What essential substrate for glycolysis is produced by the conversion of pyruvate to lactate?

NAD+

What is the name of the enzyme that catalyzes the conversion of pyruvate to lactate and pyruvate to acetyl CoA respectively?

lactate dehydrogenase; pyruvate dehydrogenase

Lactate is an energy source in the body and can be converted back to glucose in the liver, heart, kidney, and inactive muscle.

True!

Acetyl CoA is a large molecule that has 21 carbons.

False. It's a coenzyme that has 21 carbons (the acetyl group has 2 carbons)

During the conversion of pyruvate to acetyl-CoA, what 2 types of biochemical processes
take place?

Dehydrogenase and decarboxylase

How does pyruvate get transported into the mitochondria?

What type of protein structure does pyruvate dehydrogenase have?

Quaternary

How many enzymes are in the pyruvate dehydrogenase enzyme complex?

Dehydrogenase, decarboxylatase, hydratase, substrate level phosphorylatase enzymes (5)

What molecule does acetyl-CoA react with in the first reaction of the citric acid cycle?

Oxoloacetate

What is the limiting factor for the functioning of the ETC?

Oxygen