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Exploring how humans use microbiology in food production, medicine, and environmental cleanup.
What if I told you that some of the world's smallest living things are actually the world's greatest chefs, cleaners, and doctors?
Microbes change our food through a process called fermentation. Yeast is a single-celled fungus that eats the sugar in bread dough. As it eats, it releases carbon dioxide gas (). These gas bubbles get trapped in the dough, causing it to rise and become fluffy. Other microbes, like Lactobacillus bacteria, are used to make yogurt and cheese. These bacteria consume the sugar in milk (lactose) and produce lactic acid. This acid thickens the milk and gives yogurt its signature tangy flavor. Without these microscopic helpers, our diets would be much flatter and less flavorful!
1. Mix flour, water, sugar, and yeast. 2. The yeast begins to consume the sugar. 3. Chemical reaction: . 4. The gas creates thousands of tiny pockets in the dough. 5. Heat from the oven evaporates the alcohol and sets the bread's structure.
Quick Check
Which specific gas is responsible for making bread dough expand and rise?
Answer
Carbon dioxide ()
In nature, nothing goes to waste thanks to decomposers. These are microbes like bacteria and fungi that break down dead plants and animals. This process is called nutrient cycling. Decomposers secrete enzymes that dismantle complex organic molecules into simple nutrients like Nitrogen () and Phosphorus (). These nutrients are released back into the soil, where they can be absorbed by plant roots to help new life grow. Without decomposers, the Earth would be covered in waste, and the soil would eventually run out of the 'building blocks' needed for plants to survive.
1. A leaf falls from a tree. 2. Fungi (decomposers) grow on the leaf and break down its cell walls. 3. The fungi release minerals back into the dirt. 4. A new sapling absorbs those minerals: . 5. This creates a continuous loop of energy and matter.
Quick Check
What would happen to an ecosystem if all the decomposers suddenly disappeared?
Answer
Dead matter would pile up and the soil would lose the nutrients needed to grow new plants.
Modern medicine uses biotechnology to turn bacteria into tiny factories. One of the most famous examples is the production of insulin, a hormone needed by people with diabetes. Scientists take the human gene that contains the 'instructions' for making insulin and insert it into a bacterial plasmid (a small, circular piece of DNA). Because bacteria multiply very quickly, they can produce massive amounts of human insulin in a very short time. This process is much safer and more efficient than older methods of gathering insulin from animals.
1. Scientists 'cut' a bacterial plasmid using special enzymes. 2. They 'paste' the human insulin gene into the gap. 3. The modified plasmid is put back into an E. coli bacterium. 4. The bacterium 'reads' the human DNA and starts building the insulin protein. 5. The bacteria divide every 20 minutes: growth means millions of 'medicine factories' are created in hours.
Which process do microbes use to turn milk into yogurt?
What is a 'plasmid' in the context of biotechnology?
Decomposers help the environment by removing nutrients from the soil.
Review Tomorrow
In 24 hours, try to explain to a friend how a bacterium can be 'reprogrammed' to act like a human medicine factory.
Practice Activity
Check the labels on the food in your fridge (like yogurt or sourdough bread) for the words 'live active cultures' or 'yeast' to see microbes at work!