3. Molecules of Life

Page 1: Copyright Notice

  • This material has been reproduced and communicated by the University of Newcastle, adhering to section 113P of the Copyright Act 1968.

  • The content may be subject to copyright; any further reproduction or communication may have copyright protection.

Page 2: Course Introduction

  • Course Title: Molecules of Life (HUBS 1401)

  • Institution: The University of Newcastle, Australia

  • Textbook: Essentials of Human Anatomy & Physiology, Thirteenth Edition by Elaine N. Marieb and Suzanne M. Keller.

Page 3: Learning Outcomes

  • Distinguish between organic and inorganic compounds.

  • Explain dehydration synthesis and hydrolysis in the formation and breakdown of organic molecules.

  • Compare and contrast carbohydrates, lipids, proteins, and nucleic acids in terms of their building blocks, structures, and functions in the body.

  • Differentiate fibrous proteins from globular proteins.

  • Explain the importance of ATP in bodily functions.

Page 4: Organic Compounds

  • Characteristics:

    • Usually large and always contain carbon.

    • Often referred to as macromolecules.

    • Include significant organic compounds such as carbohydrates, lipids, proteins, nucleic acids, and ATP.

    • Most macromolecules are polymers made by linking monomer units.

Page 5: Carbohydrates

  • Composition: Contain carbon, hydrogen, and oxygen (often abbreviated as CHO).

  • Presence in the Body: Comprise less than 3% of body weight.

  • Functions:

    • Serve as an energy source (immediate and storage forms).

    • Integral part of nucleic acids.

    • Involved in cell-cell recognition.

  • Types: Subdivided into monosaccharides, disaccharides, and polysaccharides.

Page 6: Classification of Carbohydrates

  • Divided into three main groups based on chemical structure:

    1. Monosaccharides - single sugar.

    2. Disaccharides - two sugars.

    3. Polysaccharides - many sugars.

Page 7: Monosaccharides

  • Examples of Simple Sugars:

    • Glucose (blood sugar)

    • Fructose (fruit sugar)

    • Galactose (milk sugar)

    • Deoxyribose (found in DNA)

  • These serve as the building blocks of more complex carbohydrates.

Page 8: Linking Monosaccharides

  • Dehydration Synthesis: The process of joining monosaccharide monomers by removing water (H₂O).

  • Hydrolysis: The breakdown of disaccharides into monosaccharides through the addition of water.

Page 9: Disaccharides

  • Formed by linking two monosaccharides:

    • Examples:

    • Sucrose = glucose + fructose (table sugar)

    • Lactose = glucose + galactose (milk sugar)

    • Maltose = glucose + glucose (malt sugar)

Page 10: Polysaccharides

  • Complex Carbohydrates:

    • Comprise tens to hundreds of monosaccharides.

    • Important Polysaccharides:

      • Glycogen: Major carbohydrate store in humans, which can be broken down to release glucose for energy.

Page 11: Lipids

  • Types: Includes fats, oils, and sterols.

  • Solubility: Mostly insoluble in water and require special transport mechanisms.

  • Composition: Contain C, H, and O (less O than carbohydrates).

  • Functions:

    • Essential structural components of all cells.

    • Serve as important energy reserves (twice the energy per gram compared to carbohydrates).

    • Comprise 12-18% of the total body weight in adult males and 18-24% in adult females.

Page 12: Fatty Acids

  • Saturated Fatty Acids: Each carbon atom in the hydrocarbon tail has four single covalent bonds.

  • Unsaturated Fatty Acids: Some C to C bonds are double bonds, affecting the shape and making them liquid at room temperature (RT).

Page 13: Triglycerides

  • Role: Main lipids in the body used for energy (fatty deposits hydrolyzed to fatty acids), insulation, and protection around internal organs.

  • Structure: Composed of three fatty acids linked to a glycerol molecule.

Page 14: Phospholipids

  • Composed of a polar phosphate group and two fatty acids.

  • Essential for forming and maintaining cell membranes, with a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tails.

Page 15: Proteins

  • Abundance: Most abundant macromolecules in the body, contributing to 12-18% of body weight.

  • Structure: Constructed from monomers called amino acids, linked by peptide bonds.

Page 16: Functions of Proteins

  • Structural Support: Includes collagen and keratin.

  • Regulatory Functions: Hormones and neurotransmitters.

  • Movement: Involved in muscle contraction (e.g., actin and myosin).

  • Immunological: Form antibodies and other immune proteins.

  • Transport: Includes hemoglobin, HDL, LDL.

  • Catalytic: Enzymes speed up biochemical reactions.

Page 17: Structural Levels of Proteins

  • Proteins generally exhibit four levels of structure:

    • Primary: Sequence of amino acids.

    • Secondary: Local folding patterns (e.g., alpha-helix, beta-pleated sheet).

    • Tertiary: Overall 3D structure.

    • Quaternary: Complexes of multiple polypeptide chains.

Page 18: Enzymes as Proteins

  • Function: Act as biological catalysts that regulate and accelerate biochemical reactions.

  • Characteristics:

    • Not consumed in reactions.

    • Most enzymes and their names typically end with "-ase" (e.g., lipase, protease).

Page 19: Properties of Enzymes

  • Specificity: Highly specific to their substrates, catalyzing specific reactions.

  • Efficiency: Can increase reaction rates drastically, by factors of up to 10 billion.

  • Control: Concentrations regulated by genetic control; may require cofactors for activity (e.g., minerals, vitamins).

Page 20: Mechanism of Enzyme Action

  • Enzymes act upon specific substrates, transforming them into products through chemical reactions, highlighting the example of different enzymes acting on their respective substrates (e.g., proteases on proteins, lipases on lipids).

Page 21: Nucleic Acids

  • Types: Includes DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

  • Functions:

    • DNA: Stores genetic information for development, survival, and reproduction.

    • RNA: Conveys genetic instructions from DNA for protein synthesis.

Page 22: Structure of Nucleic Acids

  • Components:

    • Constructed from nucleotides, which consist of:

      • Pentose sugar (ribose or deoxyribose)

      • Phosphate group

      • Nitrogenous bases (adenine, guanine, cytosine, thymine, uracil for RNA).

Page 23: DNA Structure

  • Configuration: DNA consists of two strands forming a double helix structure.

  • Components of Each Strand: Nucleotides are linked with deoxyribose sugars and phosphate groups, and nitrogenous bases pair (A with T, G with C) through hydrogen bonds.

Page 24: Adenosine Triphosphate (ATP)

  • Function: Acts as an energy carrier in living systems.

  • Energy release occurs through hydrolysis, catalyzed by the enzyme ATPase, producing ADP and free phosphate.

Page 25: Summary of Organic Compounds

  • Key Points:

    • Organic compounds primarily contain carbon.

    • Serve various functions including structural, energy storage, genetic material, and regulation of cellular functions.

    • The four main types of organic molecules are carbohydrates, lipids, proteins, and nucleic acids.

    • ATP is recognized as the principal source of energy for cellular activities.

Copyright Notice

This material has been reproduced and communicated by the University of Newcastle, adhering to section 113P of the Copyright Act 1968. The content may be subject to copyright; any further reproduction or communication may have copyright protection.

Course Introduction

Course Title: Molecules of Life (HUBS 1401)

Institution: The University of Newcastle, Australia

Textbook: Essentials of Human Anatomy & Physiology, Thirteenth Edition by Elaine N. Marieb and Suzanne M. Keller. This textbook provides a comprehensive overview of human anatomy and physiology, suitable for students of various disciplines.

Learning Outcomes

Upon successful completion of this course, students will be able to:

  • Distinguish between organic and inorganic compounds, understanding their chemical properties and significance in biological systems.

  • Explain the processes of dehydration synthesis and hydrolysis in the formation and breakdown of essential organic molecules, emphasizing their roles in metabolism.

  • Compare and contrast carbohydrates, lipids, proteins, and nucleic acids in terms of their building blocks (monomers), structures, and diverse functions within the human body.

  • Differentiate between fibrous proteins (structural) and globular proteins (functional) based on their roles and properties.

  • Explain the crucial importance of ATP (Adenosine Triphosphate) in various bodily functions, particularly its role as the primary energy currency in cells.

Organic Compounds

Characteristics:

  • Organic compounds are usually large molecules characterized by the presence of carbon atoms, which form the backbone of their structure.

  • Often referred to as macromolecules, these compounds are critical for various biological functions and processes.

  • Major classes of organic compounds include carbohydrates, lipids, proteins, nucleic acids, and ATP. Each class plays a distinct role in cellular function and health.

  • Most macromolecules are polymers, composed of repeating units called monomers, which link together through various types of chemical bonds.

Carbohydrates

Composition:

  • Carbohydrates are organic compounds composed of carbon (C), hydrogen (H), and oxygen (O), typically in a ratio of 1:2:1 (often abbreviated as CHO).

Presence in the Body:

  • They comprise a small proportion of body weight, typically less than 3%, yet play vital roles in various physiological processes.

Functions:

  • Carbohydrates serve as a primary energy source, providing both immediate energy and storage forms for later use.

  • They are integral components of nucleic acids, essential for genetic information storage and transfer.

  • Carbohydrates are involved in cell-cell recognition processes, which are vital for cellular communication and immune response.

Types:

  • Carbohydrates are divided into three main categories based on their chemical structure:

    • Monosaccharides: The simplest form, consisting of single sugar units.

    • Disaccharides: Composed of two monosaccharides linked together.

    • Polysaccharides: Long chains of monosaccharides, serving as energy reserves or structural components.

Classification of Carbohydrates

  • Monosaccharides: Examples include glucose (common blood sugar), fructose (fruit sugar), galactose (a sugar found in milk), and deoxyribose (present in DNA).

  • Disaccharides: Examples include sucrose (common table sugar), lactose (found in milk), and maltose (used in brewing).

  • Polysaccharides: Examples include starch (energy storage in plants), glycogen (energy storage in animals), and cellulose (a structural component in plant cell walls).

Linking Monosaccharides

  • Dehydration Synthesis: A biochemical process where two monosaccharides are joined by removing a molecule of water, forming a covalent bond, and creating a disaccharide.

  • Hydrolysis: The process of breaking down disaccharides into their monosaccharide components by the addition of water, critical for digestion and metabolism.

Disaccharides

  • Disaccharides are formed by linking two monosaccharides through glycosidic bonds:

    • Examples:

      • Sucrose = glucose + fructose (table sugar)

      • Lactose = glucose + galactose (milk sugar)

      • Maltose = glucose + glucose (malt sugar)

Polysaccharides

  • Complex carbohydrates, comprising tens to hundreds of monosaccharides:

    • Important Polysaccharides:

      • Glycogen: The major carbohydrate storage form in humans, stored primarily in the liver and muscles, which can be broken down into glucose for energy needs during physical activity.

      • Starch: A storage polysaccharide in plants, serving as a significant source of energy when consumed.

      • Cellulose: A polysaccharide that provides structural support in plant cell walls but is not digestible by humans.

Lipids

Types:

  • Include diverse molecules such as fats, oils, phospholipids, and sterols (e.g., cholesterol).

Solubility:

  • Lipids are predominantly insoluble in water and typically require special transport mechanisms within the body (e.g., lipoproteins).

Composition:

  • Lipids consist of carbon (C), hydrogen (H), and oxygen (O), but contain less oxygen than carbohydrates, making them more energy-dense.

Functions:

  • They serve as essential structural components of cellular membranes.

  • Lipids act as important energy reserves, providing twice the energy per gram compared to carbohydrates, making them a crucial source of fuel.

  • Comprise 12-18% of total body weight in adult males and 18-24% in adult females, reflecting variations in body composition and fat distribution.

Fatty Acids

  • Saturated Fatty Acids: Have no double bonds between carbon atoms in their hydrocarbon chains, typically solid at room temperature.

  • Unsaturated Fatty Acids: Contain one or more double bonds, which introduce kinks in the chain, making them liquid at room temperature and commonly found in plant oils.

Triglycerides

  • Role: The main form of lipid storage in the body, used for energy, insulating body organs, and providing cushioning for vital structures.

  • Structure: Composed of three fatty acids esterified to a glycerol backbone.

Phospholipids

  • Composed of a polar phosphate head and two hydrophobic fatty acid tails. They play a crucial role in forming and maintaining cellular membranes, creating a bilayer that separates the interior of cells from the external environment.

Proteins

Abundance:

  • Proteins are the most abundant macromolecules in the human body, making up 12-18% of total body weight.

Structure:

  • Constructed from monomers called amino acids linked by peptide bonds, forming complex three-dimensional structures critical for their function.

Functions of Proteins

  • Structural Support: Proteins such as collagen and keratin provide support and structure to cells and tissues.

  • Regulatory Functions: Proteins function as hormones and neurotransmitters, enabling body regulation and communication.

  • Movement: Proteins contribute to muscle contraction through actin and myosin filaments.

  • Immunological Role: Proteins form antibodies and other immune-related compounds that protect against pathogens.

  • Transport: Proteins such as hemoglobin (oxygen transport) and lipoproteins (transport of fats) are essential for nutrient distribution.

  • Catalytic Actions: Enzymes, which are specialized proteins, act as biological catalysts that speed up biochemical reactions, facilitating various metabolic processes.

Structural Levels of Proteins

  • Proteins showcase four levels of structural organization:

    • Primary: The sequence of amino acids in a polypeptide chain.

    • Secondary: Local folding patterns like alpha-helices and beta-pleated sheets arising from hydrogen bonding.

    • Tertiary: The overall 3D conformation of a single polypeptide chain.

    • Quaternary: The assembly of multiple polypeptide chains into a functional protein complex.

Enzymes as Proteins

Function:

  • Enzymes serve as biological catalysts, regulating and accelerating biochemical reactions that are vital for maintaining homeostasis in living organisms.

Characteristics:

  • Enzymes are not consumed in the reactions they catalyze, allowing them to be reused multiple times.

  • Many enzymes have names that end with the suffix “-ase,” indicating their function (e.g., proteases cleave proteins, lipases digest lipids).

Properties of Enzymes

  • Specificity: Enzymes are highly specific, acting on particular substrates to catalyze designated biochemical reactions.

  • Efficiency: Enzymes can drastically increase reaction rates, sometimes by factors of up to 10 billion, enabling life-sustaining metabolic processes.

  • Control: The concentration and activity of enzymes are tightly regulated by genetic mechanisms and may require cofactors such as minerals or vitamins for their catalytic activity.

Mechanism of Enzyme Action

  • Enzymes interact with specific substrates, catalyzing their transformation into products through various biochemical mechanisms, exemplified by proteases acting on proteins and lipases acting on fats, underscoring the specificity of catalytic actions.

Nucleic Acids

Types:

  • Nucleic acids fall into two primary types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Functions:

  • DNA: Serves as the genetic blueprint for living organisms, storing information crucial for development, survival, and reproduction.

  • RNA: Functions to convey genetic instructions from DNA during protein synthesis, playing multiple roles in gene expression and regulation.

Structure of Nucleic Acids

Components:

  • Nucleic acids are constructed from building blocks called nucleotides, which consist of:

    • A pentose sugar (either ribose for RNA or deoxyribose for DNA)

    • A phosphate group

    • Nitrogenous bases (adenine, guanine, cytosine, thymine in DNA, and uracil in RNA).

DNA Structure

  • Configuration: DNA is organized into a double helix structure, comprising two strands that run in opposite directions (antiparallel).

  • Components of Each Strand: Nucleotides are linked by covalent bonds between deoxyribose sugars and phosphate groups, establishing the backbone, with specific nitrogenous bases pairing through hydrogen bonds (A with T, G with C).

Adenosine Triphosphate (ATP)

  • Function: ATP functions as an energy carrier critical for various cellular processes, serving as a primary energy source for most cellular activities.

  • Energy Release: The release of energy from ATP occurs through hydrolysis, catalyzed by the enzyme ATPase, resulting in the formation of ADP (adenosine diphosphate) and a free inorganic phosphate, which can be utilized for driving endergonic reactions in biological systems.

Summary of Organic Compounds

Key Points:

  • Organic compounds primarily consist of carbon atoms and serve a multitude of vital functions within biological systems including structural components, energy storage, genetic material, and regulation of cellular functions.

  • The four main classes of organic molecules include carbohydrates, lipids, proteins, and nucleic acids, each playing unique roles in cellular physiology. ATP is notably recognized as the principal source of energy for cellular activities, underpinning metabolic processes essential for life.