Examples

Animals, plants, fungi, algae, protists.

Cyanobacteria, Gram positives & negatives, spirochaetes.

Extreme thermophiles, halophiles, methanogens.

Nucleus.

Double membrane bound, with nucleolus and pores.

None.

None.

DNA and genome structure.

Linear, histone coated (except in e.g. dinoflagellates). Histones with tails that can receive modifications that affect gene-expression. Introns in most sorts of genes, variable (often large) amounts of 'junk' DNA, large genome. Prescence and quantity of introns and other junk highly variable between organisms. Small prokaryotic genomes found within endosymbionts.

Circular, no histones. Introns only in non-mRNA genes (tRNA, rRNA, etc.), no junk, small genome. Extrachromosomal plasmids very common.

Circular, histone bound in some groups (no tails). Introns only in non-mRNA genes (but distinct from those in bacteria and eukaryotes), no junk, small genome

mRNA and transcription.

mRNA is capped, poly-A tail, and spliced. Three twelve-subunit (or more) RNA polymerases, RNAP-II binds DNA using TFIID and TATA binding protein.

Simple but polycistronic. One five-subunit RNA polymerase, bind DNA through σ. Poly-A tail sometimes present, but this targets mRNA for degradation rather than stability.

Poly-A tail present in some groups. One eight-subunit RNA polymerase, homologous to eukaryotic RNA polymerase II, using TFIID and TATA binding protein.

tRNA and translation.

tRNA^met starts translation. Pseudouridine in common arm.

tRNA^formyl-met usually starts. No pseudouridine.

tRNA^met starts. Pseudouridine present.

rRNA and ribosomes.

80S. Large subunit generally has 3 rRNAs.

70S. Large subunit generally has 2 rRNAs.

70S, but larger than bacteria, and more closely homologous to the eukaryotic rRNAs and proteins.

Cytoskeleton and cell motility.

Three-component cytoskeleton: microfibrils (actin, myosin), microtubules (tubulin, kinesin) and intermediates (spectrin, lamin, keratin), with motor proteins causing cytoplasmic streaming. Cells move using 9+2 waving undulipodia made of tubulin: axonemes, cilia, flagella and basal bodies.

No cytoplasmic streaming or vescicular traffic, but actin (MreB/ParM) and tubulin (FtsZ) homologues are present and involved in cell division and cell polarity. Cells move using simple flagellin flagella, powered by proton gradient; in spirochaetes, this has been developed into a complex periplasmic structure.

Cells move using simple flagella, but not homologous to bacterial system: they are powered by ATP directly.

Cell division.

Mitosis, usually meiosis too, co-ordinated by tubulin-based centrosomes, MTOCs or centrioles.

Binary fission. FtsZ analogous to tubulin and involved in cell division.

Binary fission. FtsZ analogous to tubulin and involved in cell division.

Endomembranes and cytosis.

RER, SER, Golgi, secretory pathway, lysosomes, peroxisomes, vacuoles, glyoxysomes, endosomes. Various forms of cytosis: endo, exo, pino, phago, trans, myzo.

Gas 'vacuoles' may be present, but no membranes surround them. Thylakoids and chromatophores (invaginations of plasmalemma) in photosynthetic species. No cytosis.

None.

Cell membrane.

Acyl ester lipids, sterols (terpene derivative). Phosphatidylcholine and sphingolipids common.

Acyl ester lipids, no sterols or sphingolipids (terpene hopanoids instead). Phosphatidylcholine rare.

Diphytanyl diether lipids (terpenes), often lack head-groups. Some cross membrane and have rings, so the membrane is a gel, not a fluid mosaic.

Cell wall.

Cellulose, chitin or none.

Peptidoglycan, teichoates.

No peptidoglycan. Often have transmembrane terpenoid lipids that serve the same function.

Size.

Typically 10 µm. Cytoplasmic streaming allows rapid transport.

Typically 1 µm. Size largely limited by diffusion.

Typically 1 µm. Size largely limited by diffusion.

Multicellularity and endosymbiosis.

Frequently complex, multicellular. Many unicellular forms though. All are descendents of at least one endosymbiotic relationship (with mitochondria), many of two or more (plastids). Endosymbionts surrounded by (at least) a double-membrane.

Simple. Cyanobacteria form some multicellular structures with differentiation (heterocysts). No endosymbiosis, although Bdellovibrio is an intracellular parasite of other bacteria.

Simple. Nanoarchaeum and Ignicoccus form some sort of endosymbiosis (possible parasitic).

Effective antibiotics.

Cycloheximide.

Penicillin, streptomycin, etc.

Anisomycin.