Chapter 6 Biology

Endergonic Reaction:

non-spontaneous, uses energy, builds bonds

Exergonic Reaction:

spontaneous, breaks bonds, releases energy

What are some examples that we went over lecture that involve an exergonic reaction? What about exergonic reaction? (Hint: think about ATP!)

ATP hydrolysis is going to be exergonic & ATP synthesis is going to be endergonic.

ATP hydrolysis produces ADP+ Pi: ADP is stable—> exergonic

ATP synthesis produces ATP: ATP is unstable —> endergonic

In thermodynamics, a spontaneous reaction is a process that occurs naturally without the use of energy. A non-spontaneous reaction is a process that does not occur without the use of energy. Which reaction (endergonic or exergonic) is spontaneous? Which is non-spontaneous?

Endergonic is non-spontaneous, Exergonic is spontaneous

During cellular respiration and metabolism, various biochemical reactions either release or require energy. An endergonic reaction requires an input of energy to proceed.

Which of the following processes is an example of an endergonic reaction?

A) ATP hydrolysis

B) Glycolysis (overall reaction)

C) The phosphorylation of glucose to glucose-6-phosphate

D) The breakdown of pyruvate into acetyl-CoA

E) None of the above.

C) The phosphorylation of glucose to glucose-6-phosphate —> building bonds, endergonic

A) ATP hydrolysis —> exergonic 

B) Glycolysis (overall reaction) —> Breaking bonds, exergonic reaction

C) The phosphorylation of glucose to glucose-6-phosphate —> building bonds, endergonic

D) The breakdown of pyruvate into acetyl-CoA —> Breaking bonds, exergonic

E) None of the above.

Cells rely on exergonic reactions to release energy for cellular processes. An exergonic reaction releases energy, often driving endergonic reactions.

Which of the following processes is an example of an exergonic reaction?

A) The synthesis of ATP from ADP and Pi

B) The hydrolysis of ATP to ADP and Pi

C) The phosphorylation of glucose to glucose-6-phosphate

D) The formation of glucose from pyruvate in gluconeogenesis

E) None of the above.

B) The hydrolysis of ATP to ADP and Pi

The process of Cells making ATP. Tell me the process! (Hint: It involves NAD+ and NADH!)

To make ATP, cells perform: The First Law of Thermodynamics; energy cannot be created or destroyed, only transferred or transformed from one form to another.

Glucose bonds are broken —> What does this release? —→ Electrons! Where do they go to? —> NAD+ picks up elections, converted into —> NAHD —> goes ETC (electron transport chain) to produce ATP.

Which of the following is FALSE?

A) To make ATP, cells use the first law of thermodynamics.

B) When glucose breaks down, its bonds are broken which releases energy.

C) When NADH contains electrons, it is converted into NAD+.

D) All of the above are true.

E) B and C

C) When NADH contains electrons, it is converted into NAD+. —> NAD+ contains electrons, it converts to NADH

A spontaneous reaction is not necessarily a ____ reaction.

fast

What are enzymes?

Protein catalysts that increase the rate of the reaction

What do enzymes do to the activation barrier?

Lower the activation barrier activation.

Activation barrier: how much energy is require in order for chemical reaction to occur.

Catabolic reactions:

Think: “cata”~ catastrophe —> destruction of molecules

breaking down of macromolecules of smaller molecules —> exergonic reaction

Anabolic reactions:

synthesizing macromolecules from smaller molecules —> endergonic reaction

Catabolic reactions break down larger molecules into smaller ones, releasing energy. Which of the following scenarios describes a false catabolic reaction?

A) The breakdown of glycogen into glucose molecules during exercise.

B) The conversion of pyruvate into lactate in muscle cells under anaerobic conditions.

C) The synthesis of proteins from amino acids in the body.

D) The breakdown of fatty acids into acetyl-CoA for use in the Krebs cycle

C) The synthesis of proteins from amino acids in the body.

Anabolic reactions build larger molecules from smaller ones, requiring energy input. Which of the following scenarios describes a false anabolic reaction?

A) The synthesis of glycogen from glucose molecules after a meal.

B) The production of proteins from amino acids during muscle growth.

C) The formation of glucose from pyruvate during gluconeogenesis.

D) The breakdown of triglycerides into fatty acids and glycerol during fasting.

D) The breakdown of triglycerides into fatty acids and glycerol during fasting.

Oxidation:

• OIL: oxidation is loss, removal of electrons

• Oxidation will increase in the net charge

• NADH is getting oxidized when it deposits its e- into the ETC

Reduction:

• RIG: Reduction is gain, addition of electrons

• Reduction will decrease the net charge of a molecule

• NAD+ is getting reduced as it obtains e-

How does oxidation and reduction apply to NAD+ and NADH?

They are a reversible redox couple where NAD+ is the oxidized form that accepts electrons, becoming reduced to NADH.

While NADH is the reduced form that donates electrons, becoming oxidized back to NAD+

Cellular respiration:

metabolic process in which living cells extract energy from organic molecules

What are the four parts of cell resp?

What is the equation that summarizes cellular respiration?

1. gylcolysis

2. pryruvate oxidation

3. citric acid cycle

4. oxidative phosphorylation

Process of Cellular Respiration! What are the inputs and the location they are in? What are the outputs and the where are they sent to?

1. Glycolysis

Location: cytosol

Inputs: glucose, ATP, NAD+

Output: Pyruvate, ATP NADH

Pyruvate—> mitochondrial matrix, ATP—> Ready for use, NADH—> ETC

2. Pyruvate Oxidation:

Location: mitochondrial matrix

Input: pyruvate, NAD+

Output: Acetyl (coA), NADH, CO2,

Acetyl—> Citric Acid Cycle, NADH—>ETC, CO2—>

3. Citric Acid Cycle:

Input: NAD+, FAD

Outputs: CO2, ATP, NADH, FADH2

NADH—> ETC, FADH2—> ETC, CO2—> Outside, ATP—> other parts of the cell

4. ETC:

Input: O2

Output: NAD+, FAD, H2O, H+ (contributes to gradients)

NAD+—> to glycolysis, FAD—> citric acid cycle, H2O—> go to other process, H+—> ATP synthase

5. ATP Synthase

Input: O2, ADP +Pi

Output: ATP

What is oxidized in the electron transport chain? What is reduced?

NADH and FADH2 is oxidized. NAD+ and FAD is reduced

What happens to the molecule that is oxidized? Where does it go?

NAD+ goes back to Glycolysis, Pyruvate Oxidation, and Citric Acid Cycle.

FAD goes to Citric Acid Cycle.

Where do the electrons go in the electron transport chain?

Goes through a series of complexes, which ultimately allows for H+ to be pushes out & contribute to the H+ gradient

What molecules produce H+ in the electron transport chain?

NADH and FAHD2

The electron transport proteins (the complexes) are a type of _____ transport. They pump ___ into the matrix from ___ concentration to ___ concentration in the ____ _____ _____.

1. active

2. H+

3. low

4. high

5. inner membrane space

In the electron transport chain, what has the chemical energy in glucose from glycolysis ultimately been transformed into? (Hint: think about the electrons from glucose!)

Potential energy of a proton gradient

After H+ ions have been pumped into the inner membrane space, where do they go? What type of diffusion is this?

They go to matrix. This is a Facilitated diffusion

What happens to the transporter as the H+ ions flow through?

Under goes a conformation change

Is this transporter also considered an enzyme? Yes or no? Why?

Yes, because it takes ADP + Pi and uses the energy from the H+ gradient to synthesize ATP.

A genetic mutation affects Complex IV (cytochrome c oxidase) of the electron transport chain, reducing its ability to transfer electrons to oxygen.

Which of the following effects would likely occur as a result of this mutation?

A) ATP production would increase due to a stronger proton gradient.

B) NADH and FADH₂ oxidation would slow down, leading to their accumulation.

C) Oxygen consumption would increase as the cell tries to compensate.

D) The proton gradient across the inner mitochondrial membrane would become stronger.

E) None of the above

B) NADH and FADH₂ oxidation would slow down, leading to their accumulation.

A scientist discovers a mutation in ATP synthase, the enzyme responsible for producing ATP in the mitochondria. This mutation prevents H⁺ ions from passing through the enzyme into the mitochondrial matrix.

Which of the following effects would most likely occur as a result of this mutation?

A) The proton gradient would rapidly dissipate, leading to increased ATP production.

B) The electron transport chain would stop functioning immediately due to the lack of oxygen.

C) NADH and FADH₂ oxidation would slow down, leading to a buildup of electrons in the ETC.

D) The cell would rely more on oxidative phosphorylation to meet its ATP demands.

E) None of the above

C) NADH and FADH₂ oxidation would slow down, leading to a buildup of electrons in the ETC.

Glycolysis is the first stage of cellular respiration and occurs in the cytoplasm. Which of the following correctly identifies the main inputs and outputs of glycolysis?

A) Inputs: Glucose, ATP, NADH | Outputs: Pyruvate, ADP, CO₂

B) Inputs: Glucose, NAD⁺, ADP | Outputs: Pyruvate, ATP, NADH

C) Inputs: Pyruvate, NADH, ADP | Outputs: Glucose, ATP, CO₂

D) Inputs: Glucose, FADH₂, Oxygen | Outputs: Pyruvate, Water, ATP

E) None of the above

B) Inputs: Glucose, NAD⁺, ADP | Outputs: Pyruvate, ATP, NADH

The citric acid cycle (Krebs cycle) is a key metabolic pathway that occurs in the mitochondrial matrix and helps generate energy-rich molecules for the cell. Which of the following correctly identifies the main inputs and outputs of the citric acid cycle?

A) Inputs: Pyruvate, ATP, NADH | Outputs: Acetyl-CoA, CO₂, FADH₂

B) Inputs: Acetyl-CoA, NAD⁺, FAD, ADP | Outputs: CO₂, NADH, FADH₂, ATP

C) Inputs: Acetyl-CoA, FADH₂, Oxygen | Outputs: Pyruvate, NADH, CO₂

D) Inputs: Glucose, NADH, ADP | Outputs: Pyruvate, ATP, Oxygen

E) None of the above

B) Inputs: Acetyl-CoA, NAD⁺, FAD, ADP | Outputs: CO₂, NADH, FADH₂, ATP

When does fermentation occur?

Absence of O2

How does anaerobic respiration obtain its energy?

From the e- in NADH

How does NADH and pyruvate play a role in aerobic respiration?

NADH- transfers e- to pyruvate which will generate NAD+, lactic acid is produced as a by product in humans/ bacteria and ethanol yeast

When pyruvate is reduced, what product does it convert into in bacteria? What about yeast?

Bacteria- lactic acid

Yeast- ethanol