Bacteria & Viruses: Beneficial Uses & Deleterious Effects

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  • 0:00 Definition of Bacteria…
  • 1:26 Bacteria & Virus Damage
  • 2:30 Bacteria & Virus…
  • 3:32 Lesson Summary
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Lesson Transcript
Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

What are bacteria and viruses? Learn about their harmful effects, as well as the benefits some of them provide to humans. Take a quiz and see how much you've learned.

Definition of Bacteria & Viruses

When you get sick, it's probably because of a bacterium or virus. Bacteria and viruses are agents that can be dangerous to humans and other animals. But bacteria and viruses are actually very different from each other.

Bacteria are single-celled organisms that are alive, and can live inside the human body. Viruses on the other hand are particles made of DNA or RNA, a protein coat, and an envelope of lipids (fats). They're not considered to be alive, since they can only reproduce by hijacking the ability of a nearby cell to reproduce. Viruses don't have any cells themselves, so they're not single-celled organisms; they aren't organisms at all. Bacteria are tiny, and viruses are even more minuscule than bacteria. In fact, there can be as many as a billion bacterial cells in a single gram of soil.

While bacteria and viruses do make us sick in many cases, the truth is that bacteria and viruses can both help and harm humans. There are lots of bacteria in the body that we need to help digest our food, for example. Bacteria can live in symbiotic relationships with both plants and animals; relationships where both organisms benefit. In this lesson we're going to talk about the damage caused by as well as the benefits stemming from both bacteria and viruses.

Bacteria & Viruses Damage

Most bacteria and viruses have no negative effects, but the ones we notice are those that do. Bacteria and viruses can both cause damage to our bodies, but they work in different ways. Bacteria can cause infections, and it's those infections that make us sick. Bacteria that do this are called pathogenic. They can cause diseases like cholera, syphilis, tuberculosis, and bubonic plague.

Viruses on the other hand cause diseases like the common cold, chickenpox, cold sores, Ebola, and AIDS. The effects of viruses can be caused by different things depending on the virus. Sometimes the virus can kill too many cells, causing the organism to suffer ill effects. Sometimes it can cause infection in the same way as bacteria.

There are both viruses and bacteria that can exist inside the body without any negative effects at all. For example, the virus that causes cold sores is found in most humans, even those who have never had a cold sore. But some viruses, such as the AIDS virus or Ebola, can cause death.

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