Thermodynamics: Calculating ΔG and Temperature

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Questions and Answers

What occurred during the Second Stage of the origin of life?

Primitive drop-like forms of life emerged

Nucleic acids evolved through random combinations

Simple organic molecules combined to form large molecules (correct)

Coacervate drops formed from molecular complexes

What was the result of the Third Stage of the origin of life?

Coacervate drops formed from molecular complexes (correct)

Simple organic molecules combined to form large molecules

Primitive drop-like forms of life emerged

Nucleic acids evolved through random combinations

What was a characteristic of the coacervate drops?

They were heterotrophs that derived food from the environment

They were formed from simple organic molecules

They were able to reproduce through duplication

They had the capacity for chemical reactions and metabolism (correct)

What role did some of the earliest formed proteins play?

They acted like enzymes and affected the rates of reactions Signup and view all the answers

What was the significance of RNA molecules in the primordial soup?

They acted as enzymes and affected the rates of reactions Signup and view all the answers

What was a result of the Fourth Stage of the origin of life?

The capacity for reproduction and chemical reactions emerged Signup and view all the answers

What characteristic did the primitive drop-like forms of life possess?

They were heterotrophs, deriving their food from the environment Signup and view all the answers

What type of molecules might have evolved through random combinations during the Fourth Stage?

Nucleoproteins or nucleic acids Signup and view all the answers

What is the value of ΔG in the given sample calculation?

7,350 J.mol-1 Signup and view all the answers

At what temperature does ΔG equal 0?

200 K Signup and view all the answers

Who proposed the Chemosynthetic Theory?

A.I. Oparin Signup and view all the answers

What were the sources of energy in the First Stage of the origin of life?

Ultraviolet rays, electric discharge, and heat Signup and view all the answers

What is the result of the chemical reactions in the water bodies according to the Chemosynthetic Theory?

Formation of biomolecules Signup and view all the answers

What is the temperature at which the reaction becomes spontaneous?

Above 200 K Signup and view all the answers

What was the composition of the early Earth's atmosphere according to the Chemosynthetic Theory?

Methane and ammonia Signup and view all the answers

What was the experiment conducted by Stanley Miller and Harold Urey in 1953?

An experiment to study the formation of biomolecules Signup and view all the answers

What is the meaning of the Greek root 'chole' in cholesterol?

Bile Signup and view all the answers

What is the function of cholesterol in the synthesis of hormones?

It is a precursor to sex and cortical hormones Signup and view all the answers

What is the effect of ultraviolet radiation on ergosterol?

It converts ergosterol into vitamin D2 Signup and view all the answers

What is the biologically active form of vitamin D?

Calcitriol Signup and view all the answers

What is a characteristic of amphipathic lipids?

They have limited solubility in water Signup and view all the answers

What is the meaning of the Greek word 'proteios' in proteins?

Holding the first place Signup and view all the answers

What is the proportion of the five major elements that constitute proteins?

Predominantly carbon, oxygen, nitrogen, and hydrogen Signup and view all the answers

What is an example of a dynamic function of proteins?

Acting as enzymes Signup and view all the answers

What is the result of adding salts of heavy metals to a protein solution in an alkaline medium?

Precipitate formation Signup and view all the answers

What is the color of the reaction product formed when proteins react with the Biuret reagent?

Purple Signup and view all the answers

Which of the following proteins contains an aromatic nucleus?

Amino acids with an aromatic nucleus Signup and view all the answers

What is the effect of denaturation on proteins?

Change in physical, chemical and biological properties Signup and view all the answers

Which of the following agents is a physical agent of denaturation?

Heat Signup and view all the answers

What is the characteristic of simple proteins?

They are made up of amino acid subunits joined together by peptide bonds Signup and view all the answers

What is the result of hydrolysis of simple proteins?

Only amino acids are produced Signup and view all the answers

What is the classification of proteins based on their functions?

Based on functions Signup and view all the answers

Which type of protein is rich in proline and soluble in dilute acids?

Glutelins Signup and view all the answers

What is the characteristic of fibrous/scleroproteins?

Made up of polypeptide chains that are elongated and fibrous in nature Signup and view all the answers

Which protein is present in exoskeletal structures such as hair and nails?

Keratin Signup and view all the answers

What is the result of the action of acids, enzymes, or alkalis on simple and conjugate proteins?

Formation of derived proteins Signup and view all the answers

What is the characteristic of primary derived proteins?

The size of the protein molecule is not altered Signup and view all the answers

What is the example of primary derived proteins?

Proteans Signup and view all the answers

What is the characteristic of secondary derived proteins?

The protein molecule is broken down into smaller peptides Signup and view all the answers

Which type of protein is present in elastic tissues such as tendons and arteries?

Elastin Signup and view all the answers

Study Notes

Thermodynamics

The Gibbs free energy equation is ΔG = ΔH – T ΔS, which is used to determine the spontaneity of a reaction.
In the sample calculation, the ΔG value is 7,350 J.mol-1, indicating a non-spontaneous reaction.
To find the temperature at which ΔG = 0, the equation 0 = -15,000 J.mol-1 – (X)( -75 J.K-1mol-1) is used, and the solution is X = 200 K or -73℃.

The Origin and Evolution of Life

The Chemosynthetic Theory was proposed by A.I. Oparin, stating that the Earth initially consisted of hot gases and vapors that eventually cooled and formed a solid crust.
Heavy rains led to the formation of water bodies, which contained hot water and dissolved methane and ammonia.
Chemical reactions in the water led to the formation of biomolecules, including amino acids, nitrogenous bases, sugars, and fatty acids.
These biomolecules eventually combined to form proteins and nucleic acids.

Probable Stages of the Origin of Life

Stage 1: Sources of energy, such as ultraviolet rays, lightning, or heat, caused reactions that produced complex organic compounds from ammonia, methane, water, and hydrogen.
Stage 2: Simple organic molecules combined to form large molecules, including peptides, sugars, and fat molecules.
Stage 3: Large molecules combined to form multimolecular heaps or complexes, which eventually separated from the surrounding solution and formed "coacervate drops".
Stage 4: Within the coacervate drops, a form of metabolism occurred, with synthesis and breakdown of substances, and RNA molecules may have shown enzymatic activity.

Steroids

Cholesterol is an animal sterol with a hydroxyl group at C3 and a double bond between C5 and C6, with an 8-carbon aliphatic side chain attached to C17.
Functions of cholesterol include roles in membrane structure and function, synthesis of bile acids, hormones, and vitamin D.
Ergosterol occurs in plants, yeast, and fungi, and is a precursor to vitamin D2 when exposed to ultraviolet radiation.

Amphipathic Lipids

These molecules contain both hydrophobic and hydrophilic groups, making them insoluble in water and forming micelles or bilayers when mixed with water.

Proteins

Proteins are the most abundant organic molecules in living systems, composed of five major elements in a specific proportion.
Functions of proteins include structural, dynamic, and enzymatic roles.
Properties of proteins include precipitation by salts of heavy metals, and color reactions with biuret, ninhydrin, xanthoproteic, and Millon's reagents.
Denaturation of proteins occurs through physical and chemical agents, leading to a change in physical, chemical, and biological properties.
Classification of proteins can be based on chemical nature and solubility, function, or nutrition.

Classification of Proteins

Based on chemical nature and solubility: simple, conjugated, and derived proteins.
Simple proteins yield only amino acids upon hydrolysis, and include fibrous and scleroproteins like keratin, collagen, and elastin.
Derived proteins are denatured or degraded products of simple and conjugate proteins, including primary and secondary derived proteins.

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Description

Practice calculating ΔG and determining the temperature at which ΔG = 0 using the equation ΔG = ΔH – T ΔS. Apply thermodynamic concepts to solve problems.