The Chemistry of Life - Study Notes

Levels of Organization

  • Levels shown (smallest to largest): Atoms → Molecules → Cells → Tissues → Organs → Body systems → Organisms → Populations → Communities → Ecosystems → Biosphere.

  • In the diagram, there are repeated terms (e.g., ATOM, MOLECULE, CELL, TISSUE, ORGAN, ORGANISM, POPULATION, COMMUNITY, ECOSYSTEM, BIOSPHERE) illustrating the hierarchical organization of life.

  • This sequence emphasizes the structural scale from chemical to global ecological levels.

Atoms, Elements, Isotopes

  • ATOM – smallest part of an element; cannot be broken down any further.

  • ELEMENT – substance composed of one kind of atom; cannot be broken down by chemical means.

  • ISOTOPE – atoms of the same element that have different numbers of neutrons.

  • Key terms introduced early to set up chemical foundations for life.

What does an atom look like?

  • Protons (p): positive charge (+).

  • Neutrons (n): neutral charge (0).

  • Electrons (e): negative charge (−).

  • These components form the basic structure of an atom and determine chemical behavior when atoms bond.

Periodic Table of Elements – Some Important Ones

  • Elements listed as examples:

    • C = Carbon

    • H = Hydrogen

    • O = Oxygen

    • P = Phosphorus

    • K = Potassium

    • I = Iodine

    • N = Nitrogen

    • S = Sulfur

    • Ca = Calcium

    • Fe = Iron

    • Mg = Magnesium

    • Na = Sodium

    • Cl = Chlorine

  • Mnemonic to remember these elements: CHOPKINS CaFe (has) Mighty good salt (NaCl).

    • This mnemonic helps recall several essential elements that appear in biological molecules and processes.

What information is in the Periodic Table?

  • The slide indicates that each element has information associated with it (typical contents include symbol, atomic number, atomic mass, and common uses).

  • While the slide itself doesn’t list every data column, the implied idea is that the periodic table organizes essential data about each element to understand its properties and roles in biology.

Molecules and Compounds

  • MOLECULE – a chemical unit that is hard to break into constituent elements; the smallest unit of many compounds.

  • Examples of molecules:

    • {H}2(Hydrogen Gas) —H_2

    • {NH}3 (Ammonia) — NH_3

    • {H}2O (Water) — H_2O

    • {C}{55}{H}{72}{O}5 ext{N}4 ext{Mg} (Chlorophyll A) — ext{C}{55} ext{H}{72} ext{O}5 ext{N}4 ext{Mg}.

    • ext{C}6 ext{H}{12} ext{O}6 (Glucose) — ext{C}6 ext{H}{12} ext{O}6$$.

  • COMPOUND – a substance that is a combination of two or more elements; formed chemically; has definite proportions.

  • Relationship: all compounds are molecules, but not all molecules are compounds depending on whether they are bonded combinations of two or more elements.

Isotopes

  • Isotopes have the same number of electrons, so they share chemical properties.

  • RADIOACTIVE ISOTOPES – Some isotopes are radioactive; their nuclei are unstable and decay, emitting radiation.

  • Note: A sequence of numbers (6 6 6 6 6 6 6 7 8) appears in the transcript in relation to isotopes, but it is not explained. Treat as an artifact of the slide rather than a defined concept.

Chemical Composition of the Human Body

  • Humans are made up of many elements in varying proportions.

  • The four most abundant elements by mass are Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N).

  • 96% of body mass comes from four major elements.

  • 50% to 75% of body mass is water (H₂O).

  • All organic compounds contain carbon (C) and hydrogen (H).

Abundance and Uses of Elements in the Body (as given in the slide)

  • Oxygen (O)

    • Abundance: 65%

    • Uses: Respiration and water

  • Carbon (C)

    • Abundance: 18%

    • Uses: Organic molecules and carbon dioxide

  • Hydrogen (H)

    • Abundance: 10%

    • Uses: Water, organic molecules, energy

  • Nitrogen (N)

    • Abundance: 3%

    • Uses: DNA, proteins, other organic compounds

  • Calcium (Ca)

    • Abundance: 1.5%

    • Uses: Bones, teeth; muscle function

  • Phosphorus (P)

    • Abundance: 1%

    • Uses: Bones; energy

  • Potassium (K)

    • Abundance: 0.4%

    • Uses: Electrolyte; muscle contraction

  • Sulfur (S)

    • Abundance: 0.3%

    • Uses: Amino acids, proteins; cellular respiration

  • Sodium (Na)

    • Abundance: 0.15%

    • Uses: Electrolyte; fluid regulation

  • Magnesium (Mg)

    • Abundance: 0.05%

    • Uses: Bones; biochemical reactions

  • All Other Elements

    • Abundance: < 1%

    • Uses: Hemoglobin, enzymes

  • Note: Some trace elements have no known function.

Blocks/Building of Life (Contextual Heading from Slide 11)

  • The slide hints at foundational blocks that build life, likely referring to elemental building blocks and molecular components essential for biology.