Microbiology-II

Greetings, determined microbe hunter.

These lessons are much more challenging than the introductory course. Only the truly determined will make it all the way to the end. The microbes are counting on the rest to give up.

Your reward: a solid understanding of bacteria, microscopic fungi, algae, and protozoa.

Platform: Windows PCs & Chromebooks (Optimized for mouse or trackpad; Chrome or Firefox recommended)
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Сurriculum

1. Prokaryote Classification
   Biologists like putting living things into neat little groups. But bacteria and archaea don't make it easy! Some look almost identical under a microscope but are surprisingly different. Others look nothing alike but turn out to be relatives. So how do scientists figure out who's related to whom when appearances can be so misleading?
   
2. Bacterial Shapes & Cell Structures
   Bacteria come in all sorts of shapes: tiny spheres, rods, spirals, and even little commas. But what makes one bacterial cell different from another? Some have long flagella, others wear protective capsules, and some have surprisingly complicated structures hidden inside. How many of these tiny details can you recognize under a microscope?
   
3. Bacterial Growth & Reproduction
   One bacterium becomes two, then four, then eight... That's binary fission, but bacteria have a few other tricks up their sleeves. Some reproduce by budding, others break into pieces, and some form spores that can survive years of terrible conditions. Give bacteria enough food and the right temperature, and a single cell can become a whole colony before you know it.
   
4. Bacterial Genetics
   Imagine being able to pick up a useful gene from your neighbor! Bacteria do something rather like that. Besides their own chromosome, many carry little circles of DNA called plasmids. And they can acquire new genes in some surprising ways: by taking up loose DNA, exchanging it with another bacterium, or even getting help from a virus.
   
5. Bacterial Metabolism
   Plants use sunlight, animals eat food, but what about bacteria? Some photosynthesize without producing oxygen. Others get energy from sulfur or iron compounds, and many can live perfectly well without oxygen at all. Bacterial metabolism is full of surprises, especially when you start comparing photosynthesis, cellular respiration, and fermentation.
   
6. Microbial Ecology
   A spoonful of soil can be home to millions of microorganisms. And that's just one of their habitats! Some live deep underground, others float high in the clouds, and a few seem perfectly happy in boiling hot springs or extremely salty lakes. What would kill one microbe can feel like home to another.
   
7. Microbial Survival Strategies
   Boiling heat, freezing cold, too much salt, or hardly any water at all. Not exactly comfortable places to live! Yet some bacteria handle these conditions remarkably well. They have ways to protect themselves from radiation, survive chemical stress, and even resist antibiotics. Some of their survival tricks are surprisingly clever.
   
8. Oral Microbiome
   Your mouth is home to millions of tiny organisms, and they've made themselves quite comfortable! Some live on your tongue, others hide between your teeth, and whole communities of bacteria build sticky layers of dental plaque. Most are harmless under normal conditions, but change the environment a little, and some of your quiet neighbors may start causing trouble.
   
9. Gut Microbiome
   Whenever you sit down for a meal, you're feeding trillions of tiny guests too! Your digestive system is home to a whole microbiome, with bacteria that have very different tastes. Some happily munch on fiber that your body can't digest, others live on the leftovers, and some even produce vitamins. It's a surprisingly busy place down there!
   
10. Photosynthetic Bacteria
    Imagine an Earth where you couldn't take a single breath! Billions of years ago, tiny cyanobacteria began releasing oxygen through photosynthesis, gradually changing the atmosphere of our planet. But not all photosynthetic bacteria produce oxygen. Some use different pigments and chemicals to capture sunlight, and a few can thrive in places where ordinary plants wouldn't stand a chance.
    
11. Origin of Life
    Imagine Earth billions of years ago. Volcanoes erupting, meteorites falling, oceans forming, and not a living thing in sight. Yet somehow, simple chemicals eventually gave rise to the first living cells. How could that have happened? Scientists have a few fascinating ideas, from molecules assembling in shallow pools to chemical reactions deep beneath the ocean.
    
12. Endosymbiotic Theory
    Did you know that some of the tiny structures inside your cells have a bacterial past? Billions of years ago, their ancestors were free-living bacteria. Somehow, they ended up living inside other cells and never left! Mitochondria and chloroplasts still carry their own DNA, and that's just one of the clues scientists have found about their unusual history.
    
13. Microbial Symbiosis
    Living together doesn't always mean getting along! Some microorganisms help their hosts find food or stay healthy. Others take what they need and give nothing in return. And sometimes a perfectly friendly neighbor turns into a troublemaker. Symbiotic relationships can get surprisingly complicated, as these ten real-life partnerships show.
    
14. Dichotomous Key for Lichen Identification
    Have you ever noticed those strange patches growing on rocks and tree bark? They look a bit like moss, but there's a whole partnership going on inside! Fungi and algae somehow manage to live together, though they don't always get along. And telling one lichen from another can be quite a puzzle. That's where a dichotomous key comes in handy.
    
15. Algae Under the Microscope
    What do giant kelp forests and tiny green specks in a pond have in common? We call them all algae, even though some are about as closely related as you are to an oak tree. Under the microscope, things get even stranger. Tiny green spheres, long threads, swimming cells... and somehow, they're all called algae!
    
16. What Are Fungi?
    Mushrooms are easy to spot in the forest, but they're only a small part of the fungal world. Most of a fungus may be hidden underground or inside a rotting log, spreading through a network of tiny threads called hyphae. And fungi come in far more shapes and forms than you might expect. Some make mushrooms, others produce spores in tiny sacs, and some don't look like mushrooms at all.
    
17. Protist Classification
    Being made of just one cell doesn't seem to bother protists at all. Some chase their food using tiny hairs, others stretch out to catch prey, and some swim around with long flagella. With such different creatures sharing the same name, classifying living things gets rather tricky. Even a single cell can have a lot of surprises hidden inside!
    
18. Viruses
    A virus can sit around doing absolutely nothing for years. But once it gets inside the right cell, things change dramatically! It hijacks the cell's machinery to make copies of itself, sometimes destroying the cell in the process. Viruses have genes, they evolve, and they reproduce with a little help from their hosts. So why are scientists still arguing about whether they're alive?
    
19. Biogeochemical Cycles
    A fallen leaf, a handful of soil, a drop of water... The same atoms keep traveling from one place to another, sometimes passing through dozens of living organisms along the way. And microbes do much of the hard work! Follow nitrogen, sulfur, and phosphorus as they move between living things and their surroundings, and piece together the pathways that keep these biogeochemical cycles going.
    
20. Microscope Careers
    What do a crime scene investigator, a doctor, and a geologist have in common? They all might spend part of their day looking through a microscope! One searches for tiny clues, another examines cells, and a third studies minerals hidden inside rocks. Microscopy can be part of some surprisingly different careers.