Bacteria are single-celled organisms so small that a line of them could cross a pencil tip thousands of times. Yet they run big jobs in nature. Decomposer bacteria recycle nutrients by breaking down fallen leaves and dead animals, returning elements to the soil and air. Other species live in root nodules of beans and peanuts, changing nitrogen gas into forms plants can use. Inside our bodies, communities of friendly bacteria help digest food and train the immune system. Though unseen, these tiny engineers keep ecosystems—and us—working smoothly.
Comprehension Check
What is one major role of decomposer bacteria?
How do some bacteria help plants get nitrogen?
How Bacteria Live and Multiply
A typical bacterium has a cell membrane and a strong cell wall that protects it like armor. Its DNA usually forms a single circular chromosome, and extra rings of DNA called plasmids can carry helpful genes, such as antibiotic resistance. Most bacteria reproduce by binary fission: one cell copies its DNA and splits into two identical cells. They can also swap genes through conjugation, a process that passes small DNA packages between neighbors. Quick reproduction and gene sharing help bacterial populations adapt rapidly to changing environments.
Comprehension Check
What is binary fission?
What can plasmids carry?
Helpful and Harmful: Finding Balance
Most bacteria are harmless or helpful, but a few can cause disease when they invade tissues or release toxins. Doctors use antibiotics to kill or stop the growth of bacterial pathogens, yet misuse—such as stopping treatment early or using antibiotics for viral illnesses—can leave behind resistant strains. Public health guidelines stress handwashing, safe food handling, vaccination, and correct antibiotic use. Understanding both the benefits and risks of bacteria helps communities protect health while still appreciating the crucial roles these microbes play in food, medicine, and the environment.
Comprehension Check
Why is antibiotic misuse a problem?
Which action supports public health regarding bacteria?
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