Thermodynamics and Biochemical Reactions Quiz
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Questions and Answers

What is the correct definition of kinetic energy?

  • Energy associated with the heat content of a material.
  • Energy stored in an object due to its position.
  • Energy an object possesses due to its motion. (correct)
  • Energy transferred from a hot region to a cold region.

Which law of thermodynamics states that the total energy of the universe is constant?

  • Third Law of Thermodynamics
  • Second Law of Thermodynamics
  • Law of Conservation of Energy
  • First Law of Thermodynamics (correct)

Which of the following is an example of group transfer reactions?

  • Combustion reaction
  • Electrophilic addition reaction
  • Nucleophilic addition reaction (correct)
  • Acid-base reaction

What type of energy is associated with the motion of atoms or molecules?

<p>Thermal Energy (A)</p> Signup and view all the answers

In a physical or chemical change, energy is able to do which of the following?

<p>Change its form (A)</p> Signup and view all the answers

What type of reactions are anabolic reactions primarily involved in?

<p>Assembling large molecules from smaller ones (C)</p> Signup and view all the answers

Which of the following statements about catabolism is correct?

<p>It degrades nutrient molecules. (A)</p> Signup and view all the answers

What characterizes saturated hydrocarbons?

<p>They contain C-C and C-H covalent bonds. (B)</p> Signup and view all the answers

Which functional group is represented by the structure -O-C=O?

<p>Carboxyl group (A)</p> Signup and view all the answers

Which type of reaction involves the formation or breaking of chemical bonds?

<p>Multiple types, including cleavage and condensation (C)</p> Signup and view all the answers

What is the primary characteristic of a nucleophile in a biochemical reaction?

<p>It donates electrons and has a partial negative charge. (A)</p> Signup and view all the answers

Which of the following groups is a common nucleophile in biochemical reactions?

<p>Amino group (H-N) (B)</p> Signup and view all the answers

What role do electrophiles play in biochemical reactions?

<p>They accept electrons during the reaction. (A)</p> Signup and view all the answers

What drives reactants and products toward equilibrium?

<p>Free energy changes (D)</p> Signup and view all the answers

Which equation represents the relationship between free energy change and equilibrium?

<p>G = R * T * ln(Keq) (D)</p> Signup and view all the answers

What does a negative free energy change indicate about the reaction?

<p>The reaction occurs spontaneously (B)</p> Signup and view all the answers

What happens to the total energy in a closed system?

<p>It remains constant (B), It can interconvert between forms (C)</p> Signup and view all the answers

If Keq = 19 at 25°C, what will be the value of RT ln(Keq)?

<p>-7.3 kJ/mol (A)</p> Signup and view all the answers

What does the term 'free energy hill' represent in a chemical reaction?

<p>The energy profile of reactants and products (C)</p> Signup and view all the answers

Which of the following best defines entropy?

<p>The measure of disorder in a system (D)</p> Signup and view all the answers

According to the second law of thermodynamics, what occurs in the universe?

<p>Energy spreads over time (C)</p> Signup and view all the answers

What is the significance of the value of $H = H2 - H1$ in terms of spontaneity?

<p>It is not a reliable predictor of spontaneity (D)</p> Signup and view all the answers

What occurs during a spontaneous change with $H_a = igtriangleup H = 0$?

<p>The change has no energy impact (B), The change is irreversible (D)</p> Signup and view all the answers

What is Gibb's Free Energy (G) used to measure?

<p>The energy available to do work at constant temperature and pressure (B)</p> Signup and view all the answers

Which statement is true regarding entropy?

<p>Entropy increases spontaneously in a closed system (C)</p> Signup and view all the answers

What is measured in joules/Kelvin?

<p>Entropy (C)</p> Signup and view all the answers

Which statement regarding spontaneous mixing of gases is true?

<p>It occurs irreversibly without energy change (C)</p> Signup and view all the answers

What does a positive change in enthalpy (ΔH) indicate?

<p>The reaction absorbs heat, being endothermic (A)</p> Signup and view all the answers

When considering a reaction where $H = +6 kJ/mole$, what conclusion can be drawn?

<p>The reaction absorbs energy (C)</p> Signup and view all the answers

In which situation is energy wasted according to the first and second laws of thermodynamics?

<p>When TS (temperature multiplied by entropy) is subtracted from total energy (H) (A)</p> Signup and view all the answers

What implication does the increase of entropy have on a system?

<p>Energy spreads out over time (A)</p> Signup and view all the answers

Which of the following equations correctly represents the relationship of Gibb's Free Energy (G)?

<p>G = H - TS (B)</p> Signup and view all the answers

During which of the following scenarios is the total energy constant?

<p>In an isolated system (A), When energy is converted from one form to another (D)</p> Signup and view all the answers

What is the implication of a negative change in Gibb's Free Energy (ΔG)?

<p>The reaction is spontaneous (C)</p> Signup and view all the answers

Which of the following processes is considered endothermic?

<p>Melting of ice (B)</p> Signup and view all the answers

What outcome occurs when the total energy (H) of a system increases?

<p>More work can be done by the system (C)</p> Signup and view all the answers

What does a positive change in entropy ($ riangle S$) indicate about a system?

<p>The system has increased in disorder. (D)</p> Signup and view all the answers

Which condition represents an exergonic reaction?

<p>G is negative and energy is released. (D)</p> Signup and view all the answers

What is the relationship described by the equation $G = H - TS$?

<p>It is used to predict the spontaneity of a chemical reaction. (B), It defines the relationship between enthalpy, entropy, and free energy. (D)</p> Signup and view all the answers

If a reaction has a negative Gibbs free energy ($G$), what can be inferred about the reaction?

<p>The reaction releases free energy to the surroundings. (B)</p> Signup and view all the answers

How does the 2nd Law of Thermodynamics relate to living cells?

<p>Living cells increase the disorder of the universe. (B)</p> Signup and view all the answers

What characterizes an endergonic reaction?

<p>It absorbs free energy from its surroundings. (A)</p> Signup and view all the answers

In the equation $S = SC + SD – (SA + SB)$, what does $S$ represent?

<p>The total entropy change of the system. (A)</p> Signup and view all the answers

What indicates that a reaction is non-spontaneous?

<p>Positive change in free energy (G). (C)</p> Signup and view all the answers

Flashcards

Catabolism

The breakdown of complex molecules into simpler ones and releases energy.

Anabolism

The construction of complex molecules from simpler ones and requires energy.

Electronegativity

A measure of an atom's ability to attract electrons towards itself in a chemical bond. The higher the electronegativity, the stronger the attraction.

Saturated Hydrocarbons

Hydrocarbons containing only single bonds between carbon atoms. They are nonpolar and relatively unreactive.

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Functional Groups

Groups of atoms within a molecule that are responsible for its characteristic chemical reactions.

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Nucleophiles

Molecules that are attracted to positively charged atoms or regions. Often possess a lone pair of electrons or a negatively charged atom.

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Electrophiles

Molecules that are attracted to negatively charged atoms or regions. Often have a positively charged atom or a partially positive region.

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Nucleophile-Electrophile Reactions

Biochemical reactions where nucleophiles and electrophiles interact to form new bonds or break existing ones. This forms the foundation of many metabolic pathways.

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Group Transfer

A chemical reaction where a functional group, like a nucleophile, is transferred from one molecule to another.

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Nucleophilic Substitution

A type of group transfer reaction where a nucleophile attacks an electrophile and replaces a leaving group.

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Thermodynamics

The study of energy and how it changes in physical and chemical processes.

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The First Law of Thermodynamics

The total energy of the universe remains constant, it cannot be created or destroyed.

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Potential Energy

The energy stored in an object due to its position or state. For example, a book on a shelf has potential energy.

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Kinetic Energy

The energy possessed by an object due to its motion. For example, a moving car has kinetic energy.

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Conservation of Energy

The total energy of a closed system remains constant, even when energy changes form.

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Entropy (S)

The spontaneous movement of energy from a concentrated state to a dispersed state.

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Entropy (S)

A measure of the disorder or randomness in a system.

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Entropy (S)

The tendency of energy to spread over time, increasing disorder.

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Joules per Kelvin (J/K)

A unit of measurement for entropy.

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Enthalpy Change (DH)

The change in enthalpy (heat) during a reaction, indicating whether heat is absorbed or released.

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Spontaneous Change

Enthalpy change alone is not sufficient to predict the spontaneity of a reaction.

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Spontaneous Change

A change that occurs without external intervention, and often proceeds towards a state of higher entropy.

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Second Law of Thermodynamics

The entropy of the universe always increases during any spontaneous process.

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Gas Mixing

Gases mix spontaneously and irreversibly, even if there is no change in the energy of the atoms.

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Gibbs Free Energy (G)

The energy available to do work at a constant temperature and pressure.

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Gibbs Free Energy Equation

The total energy of a system (H) minus the energy wasted as disorder (TS).

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Gibbs Free Energy and Enthalpy (H)

The more energy the system has, the more potential for work.

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Gibbs Free Energy and Entropy (S)

The more ordered the system is, the more work can be done.

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Change in Gibbs Free Energy (ΔG)

The change in Gibbs Free Energy (G) during a reaction. It represents the change in useful energy.

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Exothermic Reaction

A process that releases heat energy to the surroundings. (ΔH is negative)

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Endothermic Reaction

A process that absorbs heat energy from the surroundings. (ΔH is positive)

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Spontaneous Change (Negative Δ G)

The change in Gibbs Free Energy that occurs when a reaction moves forward.

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Free Energy Change at Equilibrium

The change in free energy that occurs when a reaction reaches equilibrium.

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Equilibrium Constant (Keq)

The ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.

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Free Energy Change (ΔG)

A measure of the spontaneity of a reaction. A negative value indicates the reaction is spontaneous, while a positive value indicates it is nonspontaneous.

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Equilibrium

A state where the rates of the forward and reverse reactions are equal, resulting in no net change in the concentrations of reactants and products.

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Relationship between Free Energy Change and Equilibrium Constant

The relationship between the free energy change of a reaction and its equilibrium constant.

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Change in Entropy (DS)

The change in entropy between the initial and final states of a system. Positive change means increased disorder, negative means decreased disorder.

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Standard Free Energy Change (DG°)

The change in Gibbs free energy (DG) under standard conditions. This allows comparison of different reactions without worrying about different starting conditions.

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Exergonic Reaction

A spontaneous reaction that releases free energy, resulting in a negative DG. Cells use this to do work, like muscle contraction.

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Endergonic Reaction

A non-spontaneous reaction that requires energy input to occur, resulting in a positive DG. This type of reaction builds complex molecules.

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Do living cells defy the second law of thermodynamics?

The second law of thermodynamics states that the total entropy of the universe is always increasing. However, living organisms can appear to decrease their internal entropy by ordering molecules. This is because cells use energy from the environment to maintain order, creating more disorder elsewhere in the universe. The overall entropy of the universe is still increasing.

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Study Notes

Lecture #1: Introduction to Biochemistry

  • This is an introductory lecture to biochemistry
  • Biochemistry is the study of chemical processes within and relating to living organisms.

The Cell

  • Animal Cell vs Plant Cell: Animal cells and plant cells differ in their structures.
  • Animal Cell: Contains endoplasmic reticulum, nucleus, cytosol, nuclear envelope, plasma membrane, Golgi apparatus, vesicles, cytoskeleton, lysosomes, peroxisome, and mitochondria.
  • Plant Cell: Contains endoplasmic reticulum, nucleus, cytosol, nuclear envelope, plasma membrane, Golgi apparatus, vesicles, cytoskeleton, peroxisome, mitochondria, vacuole, cell wall, and chloroplasts.

What is Biochemistry?

  • Biochemistry connects the biological world with the chemical world.
  • 'Bios' (Greek) means life
  • 'Al-Kimya' (Arabic) means transmutation (change)
  • Chemical changes occur through electron rearrangements.
  • Life principles are explained by biological molecules' atomic structures.

The Periodic Table of the Elements

  • The Periodic Table organizes elements by atomic structural properties.
  • Elements are categorized as most abundant, common, trace, and less common.

Diversity of Life

  • Approximately 10 million different species exist in the biosphere.
  • Some species are simple, single-celled organisms; others are complex, multi-cellular organisms.
  • Biomolecules in E. coli include proteins (15%), nucleic acids (7%), carbohydrates (3%), lipids (2%), water (70%), and other (3%).

Metabolism

  • Metabolism is the summation of all catabolic and anabolic chemical reactions in a cell.
  • E. coli: Contains approximately 1000 metabolites interconverted by approximately 2000 enzymes.
  • Catabolism: Breaks down large molecules for energy.
  • Anabolism: Builds large molecules from smaller molecules, requiring energy.
  • Biochemical reactions involve 5 common types of chemical bonds changes: group transfer, internal rearrangement, cleavage, condensation, and oxidation-reduction.

Chemical Bonds

  • Electronegativity: An atom's ability to attract electrons in a chemical bond.
  • Key electronegativity values are provided.
  • Saturated Hydrocarbons: Primarily composed of carbon and hydrogen, are nonpolar.

Functional Groups

  • Functional groups containing polar covalent bonds determine molecule reactivity.
  • Examples include carbonyl, carboxyl, alcohol/hydroxyl, amino, thiol, and phosphate groups.

Nucleophiles and Electrophiles

  • Nucleophiles are electron-rich molecules that attract electron-poor molecules.
  • Electrophiles are electron-poor molecules that attract electron-rich molecules.
  • Reactivity is determined by functional group reactivity, and involves arrow pushing.

Functional Group Reactivity

  • There are specific reaction mechanisms for group transfer such as nucleophilic addition reactions and nucleophilic substitution reactions.
  • Condensation reactions are also important biochemical reactions for building molecules by linking smaller molecules.

Thermodynamics

  • All living things require energy to function.

  • Thermodynamics describes energy transformation.

  • The first law of thermodynamics asserts conservation of energy.

  • The second law of thermodynamics asserts the increase in entropy (disorder) of the universe.

  • Entropy is the measure of disorder of a system.

  • Enthalpy is the heat energy of a material at constant pressure.

  • The chemical bonds in organic molecules have different forms of energy, kinetic and potential.

  • Gibbs Free Energy (G) describes the energy available to do work at a constant temperature and pressure.

  • ΔG (change in free energy ) can determine whether a reaction is spontaneous and/or exergonic or endergonic (non-spontaneous).

  • Chemical, physical and thermal processes change states of matter and energy in predictable ways.

  • Spontaneous processes increase the entropy of the universe.

Equilibrium

  • In a closed system, reactions proceed to equilibrium where the forward and reverse reaction rates are equal.
  • Equilibrium is determined by the equilibrium constant (Keq)

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CHEM2770 Lecture #1 - Introduction to Biochemistry PDF

Description

Test your understanding of kinetic energy, thermodynamic laws, and biochemical reactions with this quiz. It covers key concepts such as group transfer reactions, nucleophiles, and the characteristics of hydrocarbons. Perfect for students looking to reinforce their knowledge in chemistry and thermodynamics.

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