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BIO 111 · Famous Organisms

They changed everything.

8 organisms — prokaryotes and eukaryotes — that rewrote biology, won Nobel Prizes, saved millions of lives, and occasionally survived space disasters.

8
Organisms
6+
Nobel Prizes
3.5B
Years of history
1
Space survivor
Famous Prokaryotes
4 organisms
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Escherichia coli (E. coli)
The most studied organism on Earth
Prokaryote Bacteria Gram-negative Rod-shaped
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Why you should know it
E. coli lives in your gut right now and is essential to your digestion — it helps produce vitamin K and outcompetes harmful bacteria. But certain strains (like O157:H7) cause serious hemorrhagic foodborne illness. Extremely relevant to food safety and dairy manufacturing.
Famous for
Being the workhorse of molecular biology. Scientists have used E. coli to produce insulin, map genes, study DNA replication, and clone virtually every gene of interest. It doubles every 20 minutes under ideal conditions — faster than almost any other research organism.
Cell biology
Single-celled prokaryote with a circular chromosome — no membrane-bound nucleus. 70S ribosomes. Flagella for movement. Gram-negative: thin peptidoglycan layer plus an outer membrane. ~2 μm long.
💡 Your body contains roughly as many E. coli cells as human cells. The vast majority are completely harmless — in fact, you need them.
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Streptococcus thermophilus
The bacterium that makes your yogurt
Prokaryote Bacteria Gram-positive Thermophilic
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Why you should know it
Thermophilic lactic acid bacteria used in yogurt fermentation alongside Lactobacillus bulgaricus. Grows best at 40–45°C. Produces lactic acid that lowers pH, coagulates milk proteins, and creates yogurt's characteristic texture and tang. Directly relevant to your work at Origin Food Group — it's in every batch.
Famous for
Being one of the two legally required starter cultures in Grade A yogurt production. Under FDA standard of identity (21 CFR 131.200), yogurt must contain both S. thermophilus and L. bulgaricus. No exceptions. The FDA defines yogurt partly by the organisms that make it.
Cell biology
Gram-positive cocci (spheres) arranged in chains. No nucleus. 70S ribosomes. Thick peptidoglycan cell wall. Grows optimally at 42°C — this is precisely why inoculation temperature control in dairy manufacturing is so critical.
💡 S. thermophilus is why a cold inoculation tank causes quality failures — the organism can't establish dominance below its optimal temperature range, opening the door to yeast and mold overgrowth.
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Cyanobacteria
They oxygenated the entire planet
Prokaryote Bacteria Photosynthetic 2.7 billion years old
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Why you should know it
The Great Oxidation Event (~2.4 billion years ago) was caused by cyanobacteria flooding Earth's atmosphere with oxygen as a byproduct of photosynthesis. Before this, Earth's atmosphere had almost no free oxygen. Every breath you take exists because of cyanobacteria.
Famous for
Being the ancestor of chloroplasts. The endosymbiotic theory holds that ancient eukaryotic cells engulfed cyanobacteria around 1.5 billion years ago — and those engulfed bacteria became the chloroplasts in every plant cell today. The evidence: chloroplasts still have their own DNA, divide independently, and have two membranes.
Cell biology
Prokaryotes that perform oxygenic photosynthesis using thylakoid membranes right in the cytoplasm — no chloroplasts needed. Some fix nitrogen from the atmosphere. Can form filaments, mats, and complex colonies. Contain chlorophyll a and phycobiliproteins.
💡 Cyanobacterial blooms in warm lakes produce toxins (cyanotoxins) that are dangerous to humans, pets, and livestock. Climate change is making blooms more frequent worldwide.
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Staphylococcus aureus
The golden bacterium that causes big problems
Prokaryote Bacteria Gram-positive Pathogen
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Why you should know it
A major foodborne pathogen found on human skin, nasal passages, and in the environment. Produces heat-stable enterotoxins that cause rapid-onset food poisoning (1–6 hours after eating). Found in dairy, meat, and egg products. MRSA (methicillin-resistant S. aureus) is a life-threatening antibiotic-resistant strain found in hospitals.
Famous for
Being the accidental discovery that led to penicillin. In 1928, Alexander Fleming returned from vacation to find that mold (Penicillium) had contaminated his Staph cultures — and the bacteria near the mold were dead. He investigated rather than throwing it out. That moment launched the antibiotic era.
Cell biology
Gram-positive cocci that cluster in grape-like arrangements (staphylē = grape in Greek — hence the name). Thick peptidoglycan wall. Produces coagulase, toxins, and biofilm. Can survive on surfaces for months. Cells are killed by proper pasteurization — but preformed toxins in food are heat-stable and survive cooking.
💡 About 30% of people carry S. aureus in their nose asymptomatically right now. Hand hygiene before food handling is the single most effective defense against S. aureus contamination.
Famous Eukaryotes
4 organisms
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Saccharomyces cerevisiae (Baker's Yeast)
Bread, beer, and Nobel Prizes
Eukaryote Fungus Unicellular Model organism
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Why you should know it
Baker's yeast has been used by humans for at least 5,000 years for bread and fermented beverages. In food safety, yeast contamination causes spoilage in cultured dairy products — elevated YM (yeast and mold) counts on Petrifilm are a red flag in dairy QA. Yeast out-compete your starter cultures when sanitation fails or temperatures are off.
Famous for
Being the first eukaryote to have its genome fully sequenced (1996). It's used as a model organism for studying eukaryotic cell biology — its cells work like ours but are far simpler to manipulate. Research using yeast has contributed to multiple Nobel Prizes, including discoveries about cell cycle regulation and autophagy.
Cell biology
Single-celled fungus with a true nucleus, mitochondria, rough ER, Golgi, and vacuoles — a fully equipped eukaryotic cell. Cell wall made of chitin and β-glucan (not cellulose like plants). Reproduces asexually by budding. Facultative anaerobe — can survive with or without oxygen.
💡 Same yeast, completely different outcomes: with oxygen it produces CO₂ (bread rises). Without oxygen it produces ethanol (fermentation). The organism decides based on what's available.
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Arabidopsis thaliana
The lab rat of the plant world
Eukaryote Plant Model organism Multicellular
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Why you should know it
A small flowering weed used as the primary model organism in plant biology worldwide. It has a tiny genome (~135 million base pairs), a fast life cycle (6 weeks seed to seed), and produces thousands of seeds. Most of what science knows about plant development, flowering time, and pathogen defense comes from Arabidopsis.
Famous for
Being the first plant to have its full genome sequenced (2000). Sent to space multiple times to study plant growth in microgravity — critical for long-term space missions. Researchers use it to engineer drought-resistant, pest-resistant, and higher-yield crops that could feed billions more people.
Cell biology
Full eukaryotic plant cell: nucleus, chloroplasts, mitochondria, central vacuole, and a rigid cellulose cell wall. Typical plant cell dimensions ~10–100 μm. Performs both photosynthesis (in leaves) and cellular respiration (in all cells). Cells differentiate into many specialized types — root, stem, leaf, flower.
💡 Despite being a roadside weed, Arabidopsis has taught us why flowers know when to bloom (it senses day length through its leaves), and how plants fight off bacterial infections using immune receptors strikingly similar to our own.
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Caenorhabditis elegans (C. elegans)
The transparent worm that survived a space disaster
Eukaryote Animal Model organism Multicellular
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Why you should know it
A 1mm transparent roundworm that has contributed more to medicine than almost any other research animal. Its transparency allows scientists to watch every single cell in its living body in real time under a microscope. The adult has exactly 959 somatic cells — every single one has been mapped and named. Every cell fate is known.
Famous for
Leading to two separate Nobel Prizes. In 2002: the discovery of programmed cell death (apoptosis) — how cells self-destruct in a controlled way. This is fundamental to cancer biology. In 2006: the discovery of RNA interference (RNAi) — how small RNA molecules silence genes. This technology now underpins an entire class of new medicines.
Cell biology
Multicellular eukaryote with fully differentiated cell types: neurons, muscle, intestinal, reproductive. Genome fully sequenced in 1998 — the first animal. Completely transparent, enabling live fluorescence imaging of organelles inside living cells. Lifespan of ~3 weeks, making aging research fast and practical.
💡 C. elegans survived the Space Shuttle Columbia disaster on February 1, 2003. The worms' sealed canisters were recovered from the debris field in Texas — all alive and reproducing normally. They remain the only living survivors of the accident.
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Plasmodium falciparum
The deadliest eukaryote on Earth
Eukaryote Protist Parasite Unicellular
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Why you should know it
The parasite that causes the most severe form of malaria. Transmitted by Anopheles mosquitoes. Kills hundreds of thousands of people annually — mostly children under 5 in sub-Saharan Africa. Has shaped human evolution: the sickle cell trait exists because it provides partial resistance to malaria.
Famous for
Having a uniquely complex life cycle spanning two hosts — it lives in both Anopheles mosquitoes and human hosts, infecting liver cells first, then red blood cells. Its ability to continuously change the proteins on its surface lets it evade immune detection, making vaccine development extremely difficult. The first malaria vaccine (RTS,S/Mosquirix) was approved in 2021 after 30 years of development.
Cell biology
Single-celled eukaryote (protist/apicomplexa) with a nucleus, mitochondria, and a bizarre organelle called the apicoplast — an evolutionary remnant of an engulfed photosynthetic organism. Yes, a malaria parasite has the leftover remnant of what used to be a chloroplast. The apicoplast is now targeted by some antimalarial drugs.
💡 Malaria has likely killed more humans across history than any other infectious disease — estimates suggest it may have caused half of all human deaths since the Stone Age. And yet, it's caused by a eukaryote just like you.