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Learning About Viruses and Bacteria

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What Are Viruses and Bacteria?

Viruses and Bacteria. Although both can make us sick, viruses and bacteria are very different things. Viruses are sections of nucleic acids that are contained with a protein coat. In simpler terms, viruses are genetic material (RNA or DNA) that is surrounded with a protective coat. Viruses can not reproduce on their own.

Bacteria are simple single celled organisms that can reproduce on their own.

On this page we'll explore some of the similarities and difference between viruses and bacteria, as well as learn a bit more about both.

Are you a student studying biology? This page on viruses and bacteria is one of series of pages on biology topics. Links to the other pages in the series can be found near the bottom of the page.

Are viruses and bacteria alive?

Do they have the 7 characteristics of life?

Back in unit one, we explored the properties of life. Do you remember them? If not, take a quick glance at: 7 Properties of Life.

One of the properties of life is the ability to reproduce. Bacteria can reproduce, and meets the other 6 properties of life as well. Bacteria are alive.

Viruses, on the other hand, are not able to reproduce on their own. In order for a virus to reproduce, it must enter into a host cell and use the host cell's reproductive abilities. So viruses are not really living things. They don't have all the characteristics of living things. In fact, in addition to not being able to reproduce on their own, they also do not eat or make their own food. They do not grow and develop. Nor do they work toward maintaining homeostasis (maintaining a constant internal environment).

Virus means "poison"

in Latin.

Viruses contain either RNA or DNA

RNA and DNA are genetic material.

A virus is like a little pocket of genetic material. Viruses with RNA in them include HIV, influenza, hepatitis C, polio, severe acute respiratory syndrome, and rabies. Viruses with DNA in them include chickenpox, mono, and warts. It is more difficult to make vaccines against RNA viruses because of their high mutation rates.


Chickenpox virus

Viruses come in many shapes


Rotavirus (Spherical)


tobacco mosaic virus
Tobacco Mosaic Virus (rodlike)



Ebola Virus (like cooked spaghetti noodles)


Adenovirus (Polyhedral = many sides)


Bacteriophage - a virus that attacks a bacteria.

Viruses Multiply Within A Host Cell

How viruses enter a cell and replicate within it

Here are two youtube videos about viruses!
The Virusus Entry System
I really like this youtube! It provides a computerized demonstration of how a virus tricks it's way into a cell and makes more viruses which then burst out of the cell.
Viral Replication
This is another one of Mr. Paul Anderson's Bozemanbiology biology youtubes. In it, he explains how viruses reproduce using the lytic cycle. Also covered are the lysogenic cycle, and how retroviruses (like HIV) can enter into the lytic cycle.

How the HIV virus infects healthy cells

HIV infects T helper cell
by coley615 | video info

32 ratings | 19,336 views
curated content from YouTube

Bacteria

Bacteria

Bacteria are unicellular prokayrotic cells in the Eubacteria or Archaebacteria Kingdoms

Bacteria are unicellular organisms that can reproduce on their own. They are also prokaryotic, which means they are simple cells without a nucleus and without most cell organelles. (Eukaryotic cells have a nucleus and cell organelles.)

Unlike eukaryotes, bacteria:
*are multicellular
*are much smaller (with some exceptions)
*often lack cell compartmentalization
*have a single piece of DNA that's arranged in a circle
*reproduce by binary fission
*have simple flagella that spins or pili (short thick outgrowths that allow bacteria to attach to things)
*can engage in several kinds of anaerobic processes

Like Viruses, Bacteria Come In Many Shapes

Spherical, Rod shaped, and Spiral (which are sometimes more like commas or squiggly snakes).


Spirillum (Spiral or curvy)



Staphylococcus (Spherical)


Bacillus (Rod)

How Bacteria Obtain Energy

Types of Bacteria

  1. Photosynthesis - Some bacteria engage in photosynthesis and can have one of four types of photosynthetic pigments, categorizing the bacteria into four groups: purple nonsulfur bacteria, green sulfur bacteria, purple sulfur bacteria, and cyanobacteria.
  2. Chemoautotrophs - Some autotrophic bacteria get their energy from inorganic molecules (like ammonia) or organic molecules (like methane), rather than by photosynthesis.
  3. Hetererotrophs - Most bacteria get their energy by decomposing the bodies of dead organisms.

Bacteria Resources

Bacteria Lab
This is a bacteria lab in which you grow bacteria in petri dishes.
Another Bacteria Lab
This one is similar to the lab above.

Biology

List of pages in this series

Homepage: Biology: Information, Videos, and Labs

Unit 1 on Cell Biology
Biology Labs, Activities, Videos, and Study Guides About Cells (Photosynthesis, Mitosis, Cell Organelles, and More)

Unit 2 on Genetics
Labs, Information, And Videos For High School Students Studying Genetics.

Unit 3 on The History of Life on Earth
The History Of Life On Earth.

Unit 4 on Ecology
Ecological Principles / Populations
Ecosystems
Biological Communities - Symbiosis, Niches, and Biomes
Global Changes And The Environment

Unit 5 on Diversity
An Introduction to Taxonomy - The Kingdoms and Domains Of Life
Learning About Viruses And Bacteria
Protists: Paramecium, Amoebas, Algae, Diatoms, Euglena, and Others
The Fungi Kingdom

Unit 6 on All About Plants
The Plant Kingdom

Unit 7 on The Animal Kingdom: Invertebrates
The Animal Kingdom - An Introduction
Sponges are Simple Animals
The Cnidarians: Jellyfish, Sea Anemones, Hydrozoans, and Corals
Earthworms, Christmas Tree Worms, Leeches, and Other Annelids

Check back later for additional biology units!

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Comments? Questions?

  • Jolene_Belmain Feb 27, 2012 @ 12:19 pm | delete
    So many bad things out there that we need to be aware of... and as long as we try to eat and be as healthy as possible, we can hopefully start starving off these viruses and bacteria. Too bad we couldn't cut them off completely and kill them all.
  • AngryBaker Feb 24, 2012 @ 2:55 pm | delete
    I love the pix of the viruses...despite their dangerous nature, they are almost beautiful
  • paulbarton Feb 24, 2012 @ 10:21 am | delete
    fascinating stuff. Did you know that once a virus enters a cell it is invisible to the rest of the body except that the cell can signal the immune system, via cell surface glycoprotein structures, that it has a virus. The body then needs plant based antioxidant molecules, the only ones small enough to pass through the cell surface membrane, to effectively destroy the virus. If these plant based antioxidant molecules aren't available then the virus can multiply and will end up killing the cell. It then ruptures and releases millions of replicated viruses into the circulatory system each of which then seek to do the same to any cell it can get into. If ever there was a reason to eat raw fruit and vegetable this is it. Great lens.
  • EddiefromTheUsualMayhem Feb 24, 2012 @ 7:28 am | delete
    Love this lens! Thanks! (Very timely this week, too!)
  • Evelyn_Saenz Feb 24, 2012 @ 7:16 am | delete
    Another wonderful lens for learning biology.

    Blessed by a Squid Angel!
  • ajgodinho Jan 15, 2012 @ 2:47 pm | delete
    Another well documented biology lens on the topic of viruses and bacteria. Blessed!
  • OhMe Jan 13, 2012 @ 7:35 am | delete
    Very informative. Thank you for this info on Bacteria and Viruses
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© 2012 Janiece Tobey. All rights reserved.
Page last updated 6/1/12.

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Janiece

Hi! I'm an author, a vegetarian, and a homeschooling mom. I'm currently writing a book about various types of spiritual experiences women often report... more »

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