Chapter 1: Elements, Molecules and Water

Begin molecular biology with the elements shared by living systems, the dose-dependent roles of trace elements, and the molecular explanation for water's life-supporting properties.

3 simulation entries

Element Abundance and Dose Lab

Switch between mass and atom composition, then explore why an essential trace element has deficiency, healthy and toxicity zones.

Appears in: 1.1 Elements in Living Organisms

Composition lens

The same body, two different questions

OOxygen

65.0%

CCarbon

18.5%

HHydrogen

9.5%

NNitrogen

3.2%

CaCalcium

1.50%

PPhosphorus

1.00%

Oxygen dominates mass because it is abundant and each O atom is sixteen times the mass of H.

Molecule composition

Carbohydrate

C H O

Lipid

C H O (±P)

Protein

C H O N (±S)

Nucleic acid

C H O N P

Elemental patterns constrain the subunits, bonds and functional groups a molecule can contain.

Essential trace-element response

Functional range: 96% modeled performance

relative dose 42

Relative trace-element dose

Supply is sufficient without reaching damaging concentrations.

Water Properties Laboratory

Move from molecular polarity to hydration shells, a tensioned xylem column, thermal buffering and the open lattice of ice.

Appears in: 1.2 Water

Structure → interaction → property → function

Water properties laboratory

Within a molecule

Polar covalent bonds share electrons unequally. Oxygen is δ−; hydrogens are δ+.

Between molecules

Opposite partial charges attract through weaker, rapidly changing hydrogen bonds.

Many weak interactions acting together produce cohesion, surface tension and thermal stability.

Carbon and Polymer Assembly Laboratory

Track reactive functional groups through condensation and hydrolysis, then compare how the same elemental toolkit produces different molecule classes.

Appears in: 1.3 Organic Molecules in Living Organisms, 1.4 Carbohydrates, 1.5 Lipids, 1.6 Proteins, 1.7 Nucleic Acids

Atom → bond → shape → biological role