Element Inspector — what living cells are made of
The most abundant element in cells is hydrogen (H), followed by carbon (C), oxygen (O), nitrogen (N), phosphorus (P) and sulfur (S) — the macronutrients, about 99% of the dry weight of cells. Elements like Na, K, Mg, Zn, Fe, Ca, Mo, Cu, Co, Mn and V are needed only in tiny amounts: the micronutrients (trace elements). Explore them — and see why organic molecules are built on carbon.
Isomer Bench — same atoms, different arrangement
Molecules with the same atomic makeup but a different structural arrangement are isomers — and structure is always directly related to function: slight changes in arrangement can produce very different properties. Compounds with identical molecular formulas but different bonding sequences are structural isomers; isomers that differ in the spatial arrangement of atoms are stereoisomers — including the mirror-image enantiomers.
Bond Builders — monomers into macromolecules
Many biological macromolecules are formed by linking great numbers of identical or very similar smaller molecules: the building blocks are monomers, the result is a polymer. One common approach is dehydration synthesis: monomers bind end to end and water is formed as a byproduct. Cells and cell structures include four main groups of carbon-containing macromolecules: polysaccharides, proteins, lipids and nucleic acids. Build a bond yourself below.
Carbohydrate Lab — the most abundant biomolecules on earth
Carbohydrates are primarily a combination of carbon and water, many with the empirical formula (CH₂O)ₙ. They are called saccharides (Greek sakcharon, sugar). They feed us, they form the backbones of DNA and RNA, they give strength to cellulose and chitin, and they store energy as starch and glycogen.
Lipid Lab — fats, membranes and rings
Lipids are composed primarily of carbon and hydrogen (and may contain O, N, S and P). They serve as nutrients, a storage form for carbon, energy-storage molecules, and structural components of membranes and hormones. From fatty acids to sterols, this is a broad family of chemically distinct compounds — explore the main characters.
Protein Studio — from sequence to shape to function
An amino acid has a hydrogen, a carboxyl group (–COOH) and an amino group (–NH₂) bonded to the same α carbon — plus a variable R group (side chain). Amino acids link by peptide bonds (dehydration synthesis). The size and sequence of a protein determine its shape, and shape determines function. Walk the four levels of structure — then try denaturing the protein.
Chapter Quiz — Microbial Biochemistry
Twenty-two questions covering the whole chapter: elements and organic molecules, isomerism, functional groups, carbohydrates, lipids and proteins.