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?

Thermal Energy Signup and view all the answers

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

Change its form Signup and view all the answers

What type of reactions are anabolic reactions primarily involved in?

Assembling large molecules from smaller ones Signup and view all the answers

Which of the following statements about catabolism is correct?

It degrades nutrient molecules. Signup and view all the answers

What characterizes saturated hydrocarbons?

They contain C-C and C-H covalent bonds. Signup and view all the answers

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

Carboxyl group Signup and view all the answers

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

Multiple types, including cleavage and condensation Signup and view all the answers

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

It donates electrons and has a partial negative charge. Signup and view all the answers

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

Amino group (H-N) Signup and view all the answers

What role do electrophiles play in biochemical reactions?

They accept electrons during the reaction. Signup and view all the answers

What drives reactants and products toward equilibrium?

Free energy changes Signup and view all the answers

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

G = R * T * ln(Keq) Signup and view all the answers

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

The reaction occurs spontaneously Signup and view all the answers

What happens to the total energy in a closed system?

It remains constant Signup and view all the answers

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

-7.3 kJ/mol Signup and view all the answers

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

The energy profile of reactants and products Signup and view all the answers

Which of the following best defines entropy?

The measure of disorder in a system Signup and view all the answers

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

Energy spreads over time Signup and view all the answers

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

It is not a reliable predictor of spontaneity Signup and view all the answers

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

The change has no energy impact Signup and view all the answers

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

The energy available to do work at constant temperature and pressure Signup and view all the answers

Which statement is true regarding entropy?

Entropy increases spontaneously in a closed system Signup and view all the answers

What is measured in joules/Kelvin?

Entropy Signup and view all the answers

Which statement regarding spontaneous mixing of gases is true?

It occurs irreversibly without energy change Signup and view all the answers

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

The reaction absorbs heat, being endothermic Signup and view all the answers

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

The reaction absorbs energy Signup and view all the answers

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

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

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

Energy spreads out over time Signup and view all the answers

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

G = H - TS Signup and view all the answers

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

In an isolated system Signup and view all the answers

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

The reaction is spontaneous Signup and view all the answers

Which of the following processes is considered endothermic?

Melting of ice Signup and view all the answers

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

More work can be done by the system Signup and view all the answers

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

The system has increased in disorder. Signup and view all the answers

Which condition represents an exergonic reaction?

G is negative and energy is released. Signup and view all the answers

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

It is used to predict the spontaneity of a chemical reaction. Signup and view all the answers

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

The reaction releases free energy to the surroundings. Signup and view all the answers

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

Living cells increase the disorder of the universe. Signup and view all the answers

What characterizes an endergonic reaction?

It absorbs free energy from its surroundings. Signup and view all the answers

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

The total entropy change of the system. Signup and view all the answers

What indicates that a reaction is non-spontaneous?

Positive change in free energy (G). Signup and view all the answers

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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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.