Anatomy and Physiology: The Chemical Level of Organization

Anatomy and Physiology - The Chemical Level of Organization

Icebreaker Questions

  • Can you name a molecule used by or found in the human body?

    • Encourages identification of biomolecules (e.g., proteins, carbohydrates).

  • What is meant by the term “organic” molecule?

    • Organic molecules are defined as those containing carbon and hydrogen.

  • How do chemical reactions required for life occur in the body?

    • Chemical reactions occur through interactions between molecules that lead to transformations.

  • Where can you find molecules in living organisms?

    • Molecules are found in cells, tissues, and all biological structures.

Elements and Atoms: The Building Blocks of Matter

Learning Objectives 3.1.1–3.1.7
Matter

  • Matter: Anything that occupies space and has mass.

  • Mass: Amount of matter contained in an object.

    • Different from weight, as mass remains constant regardless of gravity.

    • Weight: Varies based on gravitational pull on an object.

Elements and Compounds

  • Elements: Pure substances made of a single type of atom.

  • Atom: The smallest unit of an element that retains the properties of that element.

  • Molecule: Composed of two or more atoms sharing electrons.

  • Compound: Formed when two or more elements are joined by chemical bonds.

Atomic Number, Mass Number, and Isotopes

  • Atomic number: Number of protons within an atom.

  • Atomic weight: The combined total of protons and neutrons and minor contribution from electrons.

  • Mass number: Roughly equals the total of protons and neutrons in the atom.

  • Isotopes: Different forms of an element with varying numbers of neutrons.

Ions

  • Ion: An atom with an electrical charge.

    • Can be positive (Cation) or negative (Anion).

  • Formation of ions: Occurs when atoms donate or accept electrons.

The Behavior of Electrons

  • Electron shells: Regions around an atom’s nucleus containing electrons, with a capacity of 2-8 electrons.

  • Valence shell: The outermost electron shell; relevant for chemical bonding.

    • Atoms react to completely fill their valence shell by sharing or donating electrons.

Chemical Bonds

Learning Objectives 3.2.1–3.2.3
Types of Bonds

  • Bond: Electrical attraction that holds atoms together; influenced by the number of electrons in the valence shell.

  • Three important types of bonds:

    • Ionic Bonds

    • Covalent Bonds

    • Hydrogen Bonds

Ionic Bonds

  • Formed between ions that carry opposite charges (e.g., Na+ (sodium) and Cl− (chloride) in table salt).

  • Principle: “Opposites attract” creates a strong bond between cations and anions.

Covalent Bonds

  • Formed through the sharing of electrons between atoms, stabilizing their valence shells.

  • Types of Covalent Bonds:

    • Polar Covalent Bonds: Electrons are more attracted to certain atoms.

    • Nonpolar Covalent Bonds: Electrons are shared equally between atoms.

Hydrogen Bonds

  • Occur when molecules are attracted to one another due to partial charges (e.g., between water molecules).

  • Results in properties such as surface tension.

Chemical Reactions

Learning Objectives 3.3.1–3.3.5
Characteristics of Chemical Reactions

  • Reactants (substances entering a reaction)

  • Products (substances produced by a reaction)

  • Types of reactions:

    • Synthesis Reaction: Atoms, molecules, or ions combine to form new molecules.

    • Decomposition Reaction: Larger molecules break down into smaller components.

    • Exchange Reaction: Combines elements of synthesis and decomposition reactions.

Factors Influencing the Rate of Chemical Reactions

  • Properties of Reactants: Including atomic weight and phase (solid, liquid, gas).

  • Temperature: Higher temperatures lead to faster reaction rates.

  • Concentration and Pressure: Greater concentration and pressure increase reaction rates.

  • Enzymes and Catalysts: Lower activation energy, thus speeding up reactions.

    • Activation energy: Minimal energy required for a reaction to take place.

Inorganic Compounds Essential to Human Functioning

Learning Objectives 3.4.1–3.4.5
Inorganic versus Organic Compounds

  • Inorganic Substances: Do not contain both carbon and hydrogen (e.g., water, salts, acids, and bases).

  • Organic Compounds: Contain carbon and hydrogen (e.g., carbohydrates, lipids, proteins, nucleic acids).

Water

  • Comprises 50–70% of an adult body.

  • Functions include:

    • Lubrication for joints and cushioning for cells.

    • Temperature regulation.

    • Acts as a solvent for ions/nutrients.

    • Involved in dehydration synthesis and hydrolysis reactions.

Solutions

  • Nutrients in the body are typically dissolved in water, forming solutions:

    • Solution: A mixture where one substance is dissolved in another.

    • Solvent: The substance dissolving.

    • Solutes: Substances that are dissolved.

Salts

  • Form through ionic bonding, dissociating into ions in water (excluding hydrogen (H+) and hydroxide (OH−) ions).

  • Ions formed are electrolytes allowing electrical conductivity, essential for nerve impulses and muscle contraction.

Acids and Bases

  • Acids: Release hydrogen ions (H+) in solution.

  • Bases: Release hydroxide ions (OH−) or bind hydrogen ions in solution.

pH and Buffers

  • pH scale ranges from 0 to 14, indicating acidity or alkalinity.

    • pH of 7 is neutral; closer to 0 implies acidic, closer to 14 implies alkaline solutions.

    • Buffers help maintain pH stability in biological systems.

Organic Compounds Essential to Human Functioning

Learning Objectives 3.5.1–3.5.7
Organic Biological Macromolecules

  • Composition: Consist of carbon atoms bonded usually to hydrogen, and may also include oxygen and other elements.

  • Four Major Types:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic Acids

Monomers and Polymers

  • Monomers: Individual units making up organic molecules. They bond to form polymers.

    • Major types of organic monomers:

    • Carbohydrates: Monosaccharides

    • Lipids: Fatty acids and glycerol

    • Proteins: Amino acids

    • Nucleic Acids: Nucleotide bases

Carbohydrates

  • Composed of carbon, hydrogen, and oxygen in a 2:1 ratio of hydrogen to oxygen.

  • Types:

    • Monosaccharides: Simple sugars (e.g., glucose).

    • Disaccharides: Formed from two monosaccharides (e.g., lactose).

    • Polysaccharides: Complex carbohydrates formed from multiple monosaccharides.

  • Primary source of chemical energy in the human body.

Lipids

  • Composed mainly of hydrocarbons, nonpolar, and hydrophobic.

  • Triglycerides: Most common type of lipid; serve as major energy sources and provide insulation.

Types of Lipids

  • Phospholipids: Key components of cellular membranes.

  • Cholesterol: A precursor for hormone production and stabilizes the cell membrane.

  • Prostaglandins: Involved in inflammatory responses.

Proteins

  • Composed of amino acids linked by peptide bonds.

  • Functions include cellular structure, transport of substances, and catalysis of reactions.

  • Structural Levels:

    • Primary structure: Sequence of amino acids.

    • Secondary structure: Folding of chains into alpha helices or beta sheets.

    • Tertiary structure: Further folding forming a functional shape.

    • Quaternary structure: Interactions between multiple tertiary structures.

Enzymes

  • Biological catalysts that speed up chemical reactions by lowering activation energy.

  • Typically proteins with high specificity for substrates due to the active site.

    • Active site: Region on an enzyme where substrates bind.

Nucleic Acids

  • Types:

    • Deoxyribonucleic acid (DNA): Composed of bases adenine, cytosine, guanine, and thymine; stores genetic code.

    • Ribonucleic acid (RNA): Composed of adenine, cytosine, guanine, and uracil; guides protein synthesis.

  • Structure:

    • DNA: Double-stranded helical molecule.

    • RNA: Single-stranded molecule.

Breakout Group Activity

  • Task: Determine which organic macromolecule yields the most energy for a cell, using knowledge of chemical bonds in your explanation.

Summary

  • Learning Outcomes:

    • Grasp the basic language and concepts of chemistry related to the human body.

    • Recognize organization of matter at the chemical level.

    • Define chemical bonds and the reactions they form.

    • Differentiate between organic and inorganic compounds in biological functions.