Virus vs. Bacteria Activity K12 Adaptation
(a.k.a Build-a-Virus)
Activity:
Prep Time: 20 minutes
Activity Time: 20 minutes
Team Size: 2-4 students per group
Overview of Activity:
Objective: Students will learn the structure of viruses and bacteria as well as physiological differences between
them. They will also understand that not all bacteria or viruses bad for humans, and understand the reason for
Dr. Jennifer Martiny’s research.
National Science Standards:
 Characteristics and functions of living things.
 Diversity and adaptations of organisms
 Interdependence of organisms
 Science as a human endeavor
California State Standards:
 Grade 3 – 3.a.
 Grade 4 – 3.d
 Grade 5 – 5.d
 High School – 1.c; 10.d
Background Information:
 Please visit the Martiny Lab webpage for further information
http://web.me.com/jennifermartiny/lab/Projects.html
PERFORMANCE OBJECTIVES:
Students will be able to:
1. Understand three main differences between bacteria and viruses.
2. Understand that not all viruses or bacteria are bad for humans.
3. Begin to understand the importance of marine bacteria and viruses and their effects on our own lives.
MATERIALS:
 Bend-a-roos (5 to 7 per group)
 Whiteboard (1 large)
 Whiteboard markers
 Painter’s tape (1 roll)
 Laminated print outs of virus and/or bacteria
traits, diagrams, and pictures (7 for bacteria
and 7 for viruses and 1 for both – 15 total
cards)
 Example bend-a-roo viruses (2 or 3 at least)
ADVANCE PREPARATION:
1. Create large print outs of virus and/or bacteria traits with loops of tape on the back
2. Create large print outs of virus and/or bacteria pictures with loops of tape on the back
3. Draw a Venn diagram on the whiteboard. (label one side “viruses”, label the other side
“bacteria”, and the middle “both”)
4. Draw a diagram of a virus and bacterium on the whiteboard (look at photograph for
details).
PROCEDURE:
1. Engage (2 minutes):
 Today we will learn more about the viruses and bacteria that live in the ocean.
 Did you know that there are viruses and bacteria in the ocean? If so, what do you
know about them?
 At UC Irvine, Dr. Jennifer Martiny and her research lab study marine viruses and
bacteria. More on that later!
 Now let’s play a game to know more about these tiny organisms.
2. Explore + Explain (10 minutes):
 With help from this diagram on the board, what you know, and some guessing, let’s
see if you can identify these traits of viruses and bacteria.
o Allow students to point at the correct answer and/or verbalize their thoughts for
more participation
o Have students discuss together and see if they agree with one another before
deciding if the trait appears to be a virus trait or a bacteria trait.
o Ask students why they choose their answers.
a. Which of these is Smaller//Larger?
1. Refer to diagram
2. Hint: The bacterium shown in the diagram is only the tip of the iceberg. If made
the scale, the bacterium would be the size of this cottage!
3. Answer: Viruses = smaller; Bacteria = larger
b. Which of these have a Protein Coat//Plasma Membrane or Cell Wall?
1. This answer is not on the drawing so give it your best guess.
2. Answer: Viruses = protein coat; Bacteria = plasma membrane or cell wall
c. Which of these have Do NOT have Ribosomes//HAVE Ribosomes?
1. Answer: Viruses = no ribosomes; Bacteria = have ribosomes
2. What are ribosomes?
i. Ribosomes are like the ovens of a cell if a cell were like a house. These
“ovens” help “bake” things that the cell needs like proteins.
ii. Proteins are the building blocks of cells and can even create more cells –
cell babies. Ribosomes, however, are not the power houses of a cell since
they can create things like cell parts but cannot give the cell energy.
d. Based on the last question, which of these CANNOT Reproduce on their own and
require a HOST//CAN Reproduce on their own?
e.
f.
g.
h.
1. Answer: Viruses = cannot reproduce on their own (need host); Bacteria =
reproduce on their own
2. How does that affect viruses?
i. Viruses need to infect hosts in order to reproduce. Since they cannot
reproduce on their own, they are actually not classified as living
organisms.
ii. When they infect a host, they take over the host’s ribosome “ovens” and
build their own babies. Viruses are like alien invaders that take over and
control what they infect.
Which group of examples belongs to viruses and which belongs to bacteria?
1. Ex: the flu, common cold, chicken pox, & cyanophages
2. Ex: Strep, Lactobacillus, Salmonella, E. coli, & cyanobacteria
i. Strep causes strep throat.
ii. Lactobacillus helps us make yogurt.
iii. Salmonella is in raw meats.
iv. E. coli is in our gut and helps us digest our food but can be bad if for us if
it is not in the right part of our digestive system.
3. Answer: Virus = Flu, Common Cold, Chicken Pox, & Cyanophages; Bacteria = Strep,
Lactobacillus, Salmonella, E. coli, & Cyanobacteria
Which of these diagrams is a virus//bacteria?
1. Answer: Virus = labeled green, blue, and red diagram; Bacteria = pill-shaped green
fuzzy organism with 3 long strands coming out
i. On the virus diagram, you can see that a virus almost looks like an
injection. It literally injects its nucleic acids into its host in order to take
control of the host and make the host create virus babies.
ii. If you compare our bacterium diagram on the board with this bacteria
diagram, you can see that our diagram just looks like a blob but this other
diagram has fuzzy hair-like things coming out of it.
1. The shorter fuzzy hairs are called cilia. They help propel bacteria
through the water.
2. The longer strands are called flagella. They move back and forth
like a whip to allow bacteria greater movement and speed.
3. Cilia and flagella are not to be confused with pili, which are also
hair-like things on bacteria. Pili are not used for locomotion but
for bacteria conjugation, or bacterial sexual reproduction.
Which of these photographs is a virus//bacteria?
1. These are actual photographs of viruses and bacteria. The virus picture is taken
using an atomic force microscope so viruses are extremely tiny.
2. Answer: Virus: brown photograph showing capsid, sheath, and tails; Bacteria =
collage of 4 photographs
i. Some of the bacteria in these photographs look like beads on a string.
Each bead is one bacterium. The other beads are most likely related
bacteria.
ii. Some bacteria like to stick together but others like those shown in the
yellowish picture do not.
Which of these are Not ALL Bad for Humans?
1. Be careful, this could be a trick question.
2. Answer: Both are actually not all bad for humans!
3. Although you may know that there are bacteria that are good for you, it is hard
to think of an example of good viruses.
4. In Crystal Cove at the Martiny lab, we study viruses that are good for us.
5. Most of the bacteria in the ocean are photosynthetic and called cyanobacteria.
They create energy from the sun through photosynthesis. Though this process,
they produce about 50% of the oxygen we breathe every day,
6. Because they use the sun for energy, these cyanobacteria can reproduce almost
indefinitely or until they run out of nutrients.
7. Cyanoviruses help control cyanobacteria populations. These viruses specifically
target cyanobacteria.
8. After infecting cyanobacteria, cyanophages lyse or open the bacteria to release
their virus babies. In doing this, they also release the nutrients that the bacteria
created into the environment. This allows smaller organisms like plankton to get
the food they need while the bacteria population is controlled.
9. This is how marine viruses participate in nutrient cycling in the ocean which
ultimately affects us humans higher on the food chain. This is why the Martiny
lab studies the abundance and diversity of marine viruses and bacteria.
3. Expand + Evaluate (2 minutes):
 Have visitors create their own viruses out of bend-a-roos based on the traits they just
learned.
 Have visitors help and check each other’s bend-a-roo viruses for correctness
Example of what the board should look like.
Characteristics Cards
Smaller
Larger
Have a
Protein Coat
Have a Plasma
Membrane or Cell
Wall
Do not have
Ribosomes
Have
Ribosome
Cannot Reproduce Can Reproduce on
on Their Own
Their Own (No
(Require A Host)
Host Required)
Ex: the Flu,
Common Cold,
Chicken Pox, &
Cyanophages
Ex: Strep,
Lactobacillus,
Salmonella, E. coli,
& Cyanobacteria
http://www.zeitnews.org/chemistry-physics-and-material-sciencesresearch/chemist-develops-biosensor-that-changes-color-whenbacteria-are-present-in-water-samples.html
http://www.armageddononline.org/viruses.html
http://web.me.com/jennifermartiny/lab/Projects.html
http://www.suite101.com/view_image_articles.cfm/310740
Not All Are
Bad For
Humans