Chemisty Reading AS111

Introduction to the Universe, Life, and Biochemistry

  • The Origin of Elements

    • Less than 1 second old universe: hydrogen and energy waves streaming through space.
    • Gravity caused atoms to clump together, leading to nuclear reactions that formed stars.
    • Elements such as oxygen, nitrogen, iron, and silicon created in stars; carbon condensed into dust.

  • Formation of Earth

    • 4.5 billion years ago: debris from supernovae coalesced into celestial bodies orbiting the sun.
    • Earth created from stardust, having a primordial atmosphere with methane (CH4), water (H2O), and ammonia (NH3).
    • Essential elements that compose 96% of living organisms: hydrogen, oxygen, carbon, and nitrogen.

  • Origin of Life

    • Energy sources: lightning, UV light, meteorite strikes, and geothermal activity converting gases into organic molecules (e.g., amino acids, nucleic acids).
    • Early cells evolved from self-replicating molecules, consisting of bacteria-like units without nuclei.
    • Ancient forms of bacteria: Archaebacteria, thriving in extreme, oxygen-free environments.
    • Evolution of oxygen-producing enzymes in bacteria, leading to higher atmospheric oxygen levels.
    • Biochemical models governing living entities similar across all organisms.

Matter

  • Definition of Matter: Anything that occupies space and has mass.
  • Distinction between Mass and Weight
    • Mass: The quantity of matter in an object, remains constant; Weight: the gravitational pull on that matter, varies with location (e.g., more weight on Earth than on the Moon).

States of Matter

  • Matter exists in three states: gas, liquid, solid.
    • Gas: Examples include inhaled air (oxygen) and exhaled carbon dioxide.
    • Liquid: Blood, primarily composed of water, vital for nutrient transport.
    • Solid: Musculoskeletal system includes bones, tendons, and ligaments that provide structure and strength.

Composition of Matter: Elements and Atoms

  • Elements: Pure substances made of one type of atom, represented in the Periodic Table (118 known elements).
    • Categories: metals, metalloids, nonmetals; naturally occurring (92) versus artificial.
    • Common elements include aluminum, gold, carbon, oxygen, chlorine, helium.
    • Living organisms primarily consist of four elements: nitrogen, oxygen, hydrogen, carbon.

Atoms

  • Definition: Smallest unit of an element retaining its unique properties.

    • Composition: atoms consist of protons (positive), neutrons (neutral), and electrons (negative).
    • Atomic nucleus: protons and neutrons grouped, determining atomic weight; electrons in constant motion form electron clouds.

  • Atomic Number: Number of protons in an atom determines the element.

  • Ions and Isotopes

    • Ions: Atoms that have lost or gained electrons (e.g., Na+ (cation), Cl− (anion)).
    • Isotopes: Atoms with the same number of protons but different neutrons (e.g., Carbon-14).

Chemical Bonds

  • Chemical bonds are formed by sharing or transferring electrons between atoms.
    • Types of Chemical Bonds:
    • Covalent Bonds: Strong bonds formed by electron sharing (e.g., O2, CO2, CH4).
    • Ionic Bonds: Formed by transfer of electrons, creating charged ions (e.g., NaCl).
    • Hydrogen Bonds: Weak attractions, important in molecular stability (e.g., between water molecules).

Molecules and Compounds

  • Molecules: When two or more atoms are joined by chemical bonds.
    • Compounds: Specific types of molecules formed from different elements.
    • Example reactions leading to specific molecules: O2 (diatomic oxygen), CO2 (carbon dioxide), NaCl (sodium chloride).

Mixtures and Compounds

  • Distinction between mixtures and compounds:
    1. Mixtures: Physically mixed, retain individual properties.
    2. Compounds: Chemically bonded, separated only by breaking bonds.
  • Types of mixtures: solutions (homogeneous), colloids (larger solutes), suspensions (large solutes that settle out).

Chemical Reactions

  • Types of Chemical Reactions:

    • Synthesis: New compound formed (A + B → AB).
    • Decomposition: Compound broken down into simpler substances (AB → A + B).
    • Exchange: Atoms exchanged between compounds (A + BC → AC + B).

  • Energy in Reactions: Reactions can be endergonic (absorb energy) or exergonic (release energy).

Chemical Components of Living Organisms

  • Organic vs Inorganic Compounds
    • Organic: Molecules containing carbon; examples include carbohydrates, proteins, lipids, nucleic acids.
    • Inorganic: Generally lack carbon; examples include water, salts, acids, bases.

Water and Its Properties

  • Unique properties of water include being a universal solvent, high heat capacity, and lubrication.
  • Solutes: Substances dissolved in water (e.g., salts, nutrients).
  • Hydrophilic vs Hydrophobic: Water-loving vs water-fearing molecules.

Salts, Acids, and Bases

  • Salts: Ionic compounds, important for electrolyte balance (e.g., NaCl, Ca3(PO4)2).
  • Acids and Bases: Acids release H+ ions, bases release OH- ions in water.
  • pH Scale: Ranges from 0 (acidic) to 14 (basic), with 7 being neutral.
  • Buffers: Weak acids or bases that help maintain stable pH in biological systems.

Organic Compounds

  • Carbohydrates: Used for energy and structural support (e.g., sugars, starches).
    • Monosaccharides: Simple sugars like glucose; Disaccharides: two sugars; Polysaccharides: many sugars.
  • Lipids: Include triglycerides, phospholipids, and steroids; used for energy storage and signaling.
  • Proteins: Composed of amino acids; used for structure, enzymes, and functions within the body.
  • Nucleic Acids: DNA and RNA; involved in storage and transfer of genetic information.

ATP (Adenosine Triphosphate)

  • Function: Main energy currency of the cell. Energy released from ATP is used for various biological processes.
  • Structure: Composed of adenine, ribose sugar, and three phosphate groups; breaking bonds releases energy for cellular work.