Planet Microbe – Essential Exam Notes

Big Questions & Focus

The central inquiry of studying life: how it arises, diversifies, co-evolves with environments, and its future.

Bacteria & Archaea

Prokaryotic domains that are single-celled, lack a true nucleus, have a single circular chromosome, no membrane-bound organelles, and divide by binary fission.

Eukaryotes

Organisms (like humans and owls) that form only one small branch of life, with all other branches on the universal tree being microbial.

Origin of First Microbes

The approximate time when the first microbes emerged, allowing vast time for colonization of ecological and metabolic niches.

Cells in One Gram of Soil

Approximately 10^8 cells or 100{,}000{,}000 cells.

Total Microbial Carbon Biomass

Greater than the combined carbon biomass of all plants and animals.

Total Microbial Cells on Earth

Exceeds the number of stars in the observable universe.

DNA-sequencing

Advances that reveal an ever-expanding microbial tree with immense undiscovered diversity.

Microbe Morphology

Invisible single cells to larger, colored, structured mats.

Key Planetary Roles of Microbes

Food production (e.g., fermentation), nitrogen fixation for crops, human microbiome (skin, gut), source of many medicines, foundation of forests, coral reefs, and other ecosystems, and "first responders" in environmental crises.

Oceans for Microbial Study

Environments that provide prime opportunities for studying microbes, especially those with extreme or novel metabolisms.

Bathymetry

The study of the depths of ocean or lake floors, which reveals tectonic features and underwater volcanoes, hotspots for unique microbial life.

Mid-Ocean Ridge

The world's longest mountain chain, extending 50{,}000\, ext {km} underwater, critical for deep-sea microbial ecosystems.