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?

<p>They acted like enzymes and affected the rates of reactions (A)</p> Signup and view all the answers

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

<p>They acted as enzymes and affected the rates of reactions (A)</p> Signup and view all the answers

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

<p>The capacity for reproduction and chemical reactions emerged (C)</p> Signup and view all the answers

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

<p>They were heterotrophs, deriving their food from the environment (B)</p> Signup and view all the answers

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

<p>Nucleoproteins or nucleic acids (B)</p> Signup and view all the answers

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

<p>7,350 J.mol-1 (D)</p> Signup and view all the answers

At what temperature does ΔG equal 0?

<p>200 K (C)</p> Signup and view all the answers

Who proposed the Chemosynthetic Theory?

<p>A.I. Oparin (A)</p> Signup and view all the answers

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

<p>Ultraviolet rays, electric discharge, and heat (B)</p> Signup and view all the answers

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

<p>Formation of biomolecules (D)</p> Signup and view all the answers

What is the temperature at which the reaction becomes spontaneous?

<p>Above 200 K (B)</p> Signup and view all the answers

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

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

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

<p>An experiment to study the formation of biomolecules (A)</p> Signup and view all the answers

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

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

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

<p>It is a precursor to sex and cortical hormones (D)</p> Signup and view all the answers

What is the effect of ultraviolet radiation on ergosterol?

<p>It converts ergosterol into vitamin D2 (A)</p> Signup and view all the answers

What is the biologically active form of vitamin D?

<p>Calcitriol (D)</p> Signup and view all the answers

What is a characteristic of amphipathic lipids?

<p>They have limited solubility in water (C)</p> Signup and view all the answers

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

<p>Holding the first place (B)</p> Signup and view all the answers

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

<p>Predominantly carbon, oxygen, nitrogen, and hydrogen (D)</p> Signup and view all the answers

What is an example of a dynamic function of proteins?

<p>Acting as enzymes (B)</p> Signup and view all the answers

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

<p>Precipitate formation (B)</p> Signup and view all the answers

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

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

Which of the following proteins contains an aromatic nucleus?

<p>Amino acids with an aromatic nucleus (B)</p> Signup and view all the answers

What is the effect of denaturation on proteins?

<p>Change in physical, chemical and biological properties (C)</p> Signup and view all the answers

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

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

What is the characteristic of simple proteins?

<p>They are made up of amino acid subunits joined together by peptide bonds (A)</p> Signup and view all the answers

What is the result of hydrolysis of simple proteins?

<p>Only amino acids are produced (B)</p> Signup and view all the answers

What is the classification of proteins based on their functions?

<p>Based on functions (A)</p> Signup and view all the answers

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

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

What is the characteristic of fibrous/scleroproteins?

<p>Made up of polypeptide chains that are elongated and fibrous in nature (D)</p> Signup and view all the answers

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

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

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

<p>Formation of derived proteins (B)</p> Signup and view all the answers

What is the characteristic of primary derived proteins?

<p>The size of the protein molecule is not altered (B)</p> Signup and view all the answers

What is the example of primary derived proteins?

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

What is the characteristic of secondary derived proteins?

<p>The protein molecule is broken down into smaller peptides (B)</p> Signup and view all the answers

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

<p>Elastin (D)</p> Signup and view all the answers

Flashcards

Gibbs Free Energy Equation

The Gibbs free energy equation (ΔG = ΔH – T ΔS) determines the spontaneity of a reaction based on changes in enthalpy (ΔH), temperature (T), and entropy (ΔS).

ΔG < 0

A negative ΔG value signals a spontaneous reaction, meaning it favors product formation and releases energy. A positive ΔG indicates a non-spontaneous reaction, requiring energy input to occur.

ΔG > 0

A positive ΔG value signals a non-spontaneous reaction, meaning it needs energy input to occur.

ΔG = 0

When ΔG equals zero, the reaction is at equilibrium, meaning rates of forward and reverse reactions are equal, and no net change occurs.

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Chemosynthetic Theory

The Chemosynthetic Theory, proposed by A.I. Oparin, suggests that Earth's primitive atmosphere consisted of hot gases and vapors that cooled and condensed, forming water bodies rich in methane, ammonia, and hot water.

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Early Earth's Atmosphere

The Chemosynthetic Theory states that the Earth initially had a thick atmosphere of hot gases and vapors, which cooled down over time and formed a solid crust.

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Formation of Early Water Bodies

Heavy rains in Earth's early atmosphere led to the formation of water bodies, which contained dissolved methane and ammonia alongside hot water.

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Biomolecule Formation

Chemical reactions in these early water bodies are thought to have produced simple organic molecules like amino acids, nitrogenous bases, sugars, and fatty acids.

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Macromolecule Formation

These simple biomolecules eventually combined to form complex macromolecules like proteins and nucleic acids, crucial for cellular function.

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Stage 1: Energy Sources & Organic Molecule Formation

Ultraviolet rays, lightning, and heat provided energy for chemical reactions that produced complex organic molecules from ammonia, methane, water, and hydrogen.

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Stage 2: Large molecule formation from simple molecules

Simple organic molecules, such as amino acids and fatty acids, combined into larger molecules like peptides, sugars, and fats, forming the backbone of life.

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Stage 3: Coacervate Drop Formation

Large molecules self-assembled into multimolecular heaps or complexes, which then separated from the surrounding solution, forming 'coacervate drops'.

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Stage 4: Metabolism & RNA Activity

Within the coacervate drops, metabolic processes occurred, involving synthesis and breakdown of substances, and RNA molecules may have possessed enzymatic activity.

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Cholesterol

A sterol found in animal cells, playing crucial roles in cell membrane structure and function.

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Cholesterol Function

Cholesterol serves as a precursor for bile acids aiding in fat digestion, various steroid hormones regulating body function, and vitamin D for calcium metabolism.

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Ergosterol

A plant sterol found in yeast and fungi, serving as a precursor to vitamin D2 upon exposure to ultraviolet radiation.

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Amphipathic Lipids

Lipids with a unique structure, possessing both hydrophobic (water-repelling) and hydrophilic (water-attracting) regions.

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Micelles & Bilayers

Amphipathic lipids, when mixed with water, self-assemble into spherical structures called micelles or form bilayers, essential for cell membrane formation.

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Proteins: Abundant & Composition

Proteins are the most abundant organic molecules in living systems. They are made up of five elements (Carbon, Hydrogen, Oxygen, Nitrogen, and Sulfur) in specific proportions.

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Protein Functions

Proteins have crucial structural, dynamic, and enzymatic roles in living organisms.

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Protein Precipitation

Proteins precipitate in the presence of salts of heavy metals due to the interaction between metal ions and protein side chains.

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Protein Colour Reactions

Proteins exhibit color reactions with specific reagents, such as biuret, ninhydrin, xanthoproteic, and Millon's reagents, due to their unique chemical composition.

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Protein Denaturation

Denaturation of proteins occurs when their structure is disrupted by physical or chemical agents, leading to changes in their physical, chemical, and biological properties.

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Protein Classification Overview

Proteins are classified based on their chemical nature, solubility, function, or nutritional value.

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Simple Proteins

These proteins yield only amino acids upon hydrolysis and include fibrous and scleroproteins such as keratin, collagen, and elastin.

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Derived Proteins

Derived proteins are denatured or degraded products of simple and conjugate proteins, including primary and secondary derived proteins.

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Conjugated Proteins

Conjugated proteins consist of a simple protein combined with a non-protein component called a prosthetic group.

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

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