Energy Forms and Thermodynamics

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Questions and Answers

Which statement best summarizes the First Law of Thermodynamics?

Energy naturally flows from low to high concentration.

Energy can be created and absorbed.

Energy is only conserved in closed systems.

Energy is transformed but cannot be created or destroyed. (correct)

What is the role of Gibbs Free Energy in chemical reactions?

It indicates whether a reaction can occur spontaneously. (correct)

It measures the total energy in a closed system.

It predicts the speed of enzyme reactions.

It determines the temperature of a reaction.

What is the main function of ATP in cellular processes?

To serve as a substrate for enzymatic reactions.

To store genetic information.

To act as an energy currency for coupling reactions. (correct)

To act as a transport molecule across membranes.

How do enzymes influence chemical reactions?

They lower the activation energy required for a reaction. Signup and view all the answers

What can happen if the pH of an enzyme's environment changes significantly?

The enzyme may denature and lose its functionality. Signup and view all the answers

Which statement best describes feedback inhibition in metabolic pathways?

Excess product can inhibit enzyme activity to regulate the pathway. Signup and view all the answers

Which type of inhibitor binds to an active site of an enzyme?

Competitive inhibitor. Signup and view all the answers

Which of the following is NOT a type of work done by a cell?

Thermal work. Signup and view all the answers

What is the primary role of oxygen in cellular respiration?

It serves as the final electron acceptor. Signup and view all the answers

Which process directly results in the production of ATP in glycolysis?

Substrate level phosphorylation Signup and view all the answers

What is the net gain of NADH molecules produced during glycolysis?

2 NADH Signup and view all the answers

Where does the citric acid cycle occur within the mitochondria?

In the matrix Signup and view all the answers

Which component is primarily responsible for driving ATP synthesis during oxidative phosphorylation?

Proton gradient Signup and view all the answers

How many ATP molecules are produced during oxidative phosphorylation?

28 ATP Signup and view all the answers

What is the role of phosphofructokinase in cellular respiration?

To regulate glycolysis Signup and view all the answers

What is produced during the preparation step before the citric acid cycle?

0 ATP and 2 NADH Signup and view all the answers

Study Notes

Forms of Energy

Kinetic energy is the energy of motion.
Potential energy is stored energy due to an object's position or structure.
Thermodynamics is the study of energy transformations.

The Laws of Thermodynamics

First Law: Energy cannot be created or destroyed, only converted from one form to another.
Second Law: The entropy (disorder) of the universe always increases.

Gibbs Free Energy

Gibbs Free Energy (G) is the portion of a system's energy available to do work.
A negative Gibbs Free Energy value indicates a spontaneous reaction (energy releasing).
Exergonic reactions release energy (e.g., cellular respiration).
Endergonic reactions require energy (e.g., photosynthesis).

Energy Coupling

ATP (adenosine triphosphate) is the primary energy currency of cells.
ATP hydrolysis releases energy and is coupled with endergonic reactions.
ATP hydrolysis equation: ATP + H₂O → ADP + Pi + energy

Types of Cellular Work

Chemical work: synthesis of molecules
Transport work: moving molecules across membranes
Mechanical work: movement of cells or cellular structures

Role of Enzymes in Chemical Reactions

Enzymes are biological catalysts that speed up reactions by lowering activation energy.
Activation energy is the minimum energy required for a reaction to occur.

Factors Affecting Enzyme Activity

Cofactors: non-protein molecules that assist enzyme function (e.g., calcium, iron).
pH: changes in pH can alter an enzyme's shape and function.
Temperature: extreme temperatures can denature enzymes.
Inhibitors: molecules that block enzyme activity.
- Competitive inhibitors bind to the active site.
- Non-competitive inhibitors bind to a different site, changing the enzyme's shape.
Feedback inhibition: excess product can act as an inhibitor to regulate enzyme activity.

Cellular Respiration

Cellular respiration is the process of breaking down glucose to generate ATP, CO₂, water, and heat.
Redox reactions involve the transfer of electrons.
- Oxidation is the loss of electrons.
- Reduction is the gain of electrons.
Glucose + 6O₂ → 6CO₂ + 6H₂O + ATP + Heat
Electron Transport Chain is located in the cristae of mitochondria.
Oxygen is the final electron acceptor in cellular respiration.

Stages of Cellular Respiration

Glycolysis: occurs in the cytoplasm.
- Energy investment phase uses 2 ATP.
- Energy payoff phase produces 4 ATP, 2 NADH, and 2 pyruvate.
Preparation Step: oxidizes pyruvate to acetyl-CoA, generates CO₂, and produces NADH.
Citric Acid Cycle: occurs in the mitochondrial matrix.
- Produces 2 ATP, 4 CO₂, 6 NADH, and 2 FADH₂.
Oxidative Phosphorylation: occurs in the inner mitochondrial membrane.
- Electron transport chain uses NADH and FADH₂ to generate a proton gradient.
- ATP synthase uses the proton gradient to produce ATP.

Breathing and Cellular Respiration

Breathing is the exchange of gases (oxygen in, CO₂ out).
Cellular respiration uses oxygen as the final electron acceptor and produces CO₂.

Substrate Level Phosphorylation vs. Oxidative Phosphorylation

Substrate level phosphorylation: an enzyme directly transfers a phosphate group from a substrate to ADP to produce ATP.
Oxidative phosphorylation: the electron transport chain generates a proton gradient that drives ATP synthesis.

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Description

Test your knowledge on the different forms of energy, including kinetic and potential energy, and explore the laws of thermodynamics. Additionally, understand Gibbs Free Energy and its implications for exergonic and endergonic reactions. This quiz will enhance your grasp of energy transformations in physical science.