On Your Mark, Get Set, Go!
Put away your running shoes and starting blocks. We’re not having a track
meet; we’re going to study microorganisms. Are you ready? Do you have any idea
what you will be learning? It’s always nice to have some idea where are you headed
before you start out on an adventure, so let’s see if we can get some kind of an idea.
To do that, we will look carefully at the word microorganism
Do you know what micro means? Have you ever used a microscope in your
science class or at home? Why did you use one? What kinds of things did you look
at through the microscope? Were they big or tiny? Did the microscope make them
seem larger or smaller? As you might have figured out, micro means small. That
helps us some because now we know we will be learning about something small.
The other part of our word is organism. According to the dictionary, an
organism is any form of life; any living thing. That helps us even more. Now we
know we will be learning about small, living things.
Wait a minute, we have to be sure we understand exactly what we mean
when we say we will learn about small living things. How small is small? Now we
all know that an elephant is pretty big! Does that mean that a mouse is small?
Many bugs are even smaller than mice! Are there other living things that are even
smaller than bugs?
Let’s change our definition of micro just a bit. Let’s say that micro means
too small for the human eye to see. That gives us a better idea of the size of the
living things we will be studying.
Now, let’s be sure we really understand what we mean by living things.
Scientists have studied many living things. They have found that all living things
are the same in some ways. They all have some of the same characteristics. Let’s
look at six characteristics of all living things.
1. Living things are made of cells.
A cell is the basic unit of all living things. A cell is organized to help keep an
organism alive. A cell is responsible for reproduction, for growth and development,
and for responding to the environment. Some scientists say cells are like chemical
factories. They are always busy making something to keep their organisms alive
and well. Some organisms have only one cell. Other organisms have many cells
that work together. All organisms are made of cells.
2. Living things use energy
Organisms get the energy they need from the environment. Energy is needed
for life processes. Organisms use energy to reproduce. They use energy when they
grow and develop. They also use energy when they respond to their environments.
Organisms must have a balance between the energy they get from the environment
and the energy they use for life processes. All organisms use energy.
3. Living things grow and develop.
Think about a tiny tadpole. The tadpole will get bigger, grow legs,
lose its tail, and become a frog or toad. The tadpole will grow and
develop to become and adult amphibian. Now think about a
tiny acorn. The acorn will fall to the ground, germinate, and
form roots, a stem, and leaves. The tiny acorn will grow and
develop to become a mighty oak tree. All organisms grow and
develop.
4. Living things respond to the environment.
What happens if you touch a hot burner on the stove in your kitchen? You
pull your finger away very quickly! You respond to the environment. When you
touch the hot burner, you have a stimulus. A stimulus is a change I the
environment. When you pull your finger away very quickly, you have a response. A
response is the reaction to the change in the environment. All organisms respond to
the environment.
5. Living things reproduce.
When organisms reproduce, they make more organisms that look like
themselves. If your dog has puppies, the puppies look like the parent dogs. If a
dandelion goes to seed in your yard, you will have more dandelions that look just
like the first one! All organisms reproduce.
6. Living things are adapted to their environments
Think about a Downy Woodpecker. It has four toes on each
foot. Two of the toes are facing forward, and two of them are facing
backward. The woodpecker’s toes help it hold onto the bark of a tree.
A Downy Woodpecker also has a stiff tail. This tail helps the
woodpecker balance against the trunk of a tree as it drills a hole in the
bark. A Downy Woodpecker also has a thick, pointed bill. The bill
allows the woodpecker to make holes in the hard wood of a tree to find
insects. Finally, a Downy Woodpecker has a long tongue. The
woodpecker can put its tongue into the tree to find insects. There is a tiny barb on
the end of the tongue that can hook the insects and carry them back in to the
woodpecker’s mouth for a tasty lunch or dinner. An organism must be adapted to
the environment to be able to survive. All organisms have adaptations that allow
them to live in their environments.
All living things have all six characteristics. Some kinds of matter may have
one or two characteristics, but not all six. If it does not have all six characteristics,
it is not an organism. Every organism must have all six characteristics.
Okay, let’s review our definition. A microorganism is a tiny living thing that is
too small for the human eye to see. It is made of cells, uses energy, grows, and
develops, responds to it environment, reproduces, and is adapted to survive in its
environment.
What Do You Need?
All living things have six characteristics in common. We just learned what
those six characteristics are. They also have basic needs that are the same. Let’s
take a look at what those basic needs are.
Energy
All organisms need energy. The Sun is the main source of energy for most life
on Earth. All living things either use the Sun directly or indirectly. Producers are
organisms that make their own food by using the Sun’s energy. They use their
“homemade” food to provide their energy. Without direct energy from the Sun,
produces would not be able to survive.
Consumers are organisms that eat other organisms. Some consumers eat
plants. Plants are producers. The plants use the Sun’s energy directly, but
consumers still depend on the Sun’s energy in an indirect way. Without energy
from the Sun for the produces, consumers would not have the food they need for
energy.
Food
Imagine a day without food. You would feel pretty lousy if you could not eat
anything all day. Your body needs food for proper growth. As we have already
learned, producers are organisms that make their own food. They absorb nutrients
from the environment and use those nutrients to help keep them alive.
Remember that consumers are organisms that eat other organisms. There
are three basic groups of consumers. Herbivores are consumers that eat only
plants. Carnivores are consumers that eat only animals. Omnivores are
consumers that eat both plants and animals. All consumers get nutrients from
their food sources.
Water
Organisms need water to stay alive. Water is used to dissolve and transport
substances. Nutrients are dissolved and wastes are transported in an organism’s
water supply.
Humans need water more than they need food. You can survive for a week or
more without food; however, you can only survive for a matter of days without
water. More than 70% of the human body is actually water. Water is needed by
almost all of your body systems.
For most organisms, not just any water will do. Most organisms require fresh
water; however, the majority of the Earth’s water is found in the oceans, which are
salt water. Most organisms cannot survive using salty ocean water. For example,
ocean water has more than seven times the amount of salt that a human body can
handle. In order to use ocean water, the salts must be removed.
It’s So Simple: Kingdom Monera (Bacteria)
Scientists put all living things into five kingdoms: Monera, Protista, Fungi,
Plantae, and Animalia. (We’ll look at Monera, Protista, and Fungi). Let’s look at
Monerans.
Cell Structure
Monerans cells to not have a nucleus (brain). They are called prokaryotes,
which means “before a nucleus.” They also don’t have any organelles (“little
organs”) to help with life processes. They do have cell membranes and some of the
also have cell walls. Some kinds of Monerans have chlorophyll, as well (this makes
them producers).
Number of Cells
Monerans are the simplest kinds of organisms. They have only one cell
(single-celled organism).
Kinds of Movement
Some kinds of Monerans are able to move on their own. They use simple
structures that look like whips. These are called flagella. Others cannot move.
Nutrition
Some Monerans are producers. Others are consumers.
Is it Moneran or Not?
Any organism that has these specific characteristics is a Moneran. If it
doesn’t have these characteristics, it’s not a Moneran.
Basal body – A structure that anchors the base of the flagellum and allows it to
rotate.
Capsule – A layer on the outside of the cell wall. Most but not all bacteria have a
capsule.
Cell wall – A thin membrane located outside the plasma membrane and within the
capsule.
DNA – The genetic material of the bacterium; it is located within the cytoplasm.
Cytoplasm – The jellylike material inside the plasma membrane in which the
genetic material and ribosomes are located.
Flagellum – A long whip-like structure used for locomotion (movement). Some
bacteria have more than one flagellum.
Pili (singular is pilus) – Hair-like projections that allow bacterial cells to stick to
surfaces and transfer DNA to one another.
Plasma membrane - A permeable membrane located within the cell wall. It serves
many functions for the cell, including energy generation and transport of chemicals
.Ribosome - Small organelles composed of RNA-rich granules that are sites of
protein synthesis. The ribosomes are located within the cytoplasm.
It’s Still Pretty Simple: Kingdom Protista
(Protozoan)
Cell Structure
Protozoans do have a nucleus and it’s surrounded by a nuclear membrane.
They are called eukaryotes, which means “true nucleus.” They also have cell
organelles that help the nucleus perform all the life processes.
Number of Cells
Most Protozoans are single-celled organisms. A few are made up of two or
more cells.
Kinds of Movement
Some Protozoans do not move at all, but
many of them are able to move. Some protists use
psuedopods, or false feet. The cell in this type of
protists is able to change its shape. It is able to
extend some of the cytoplasm to make a fake foot
or two. The feet are able to push or pull the cell
along.
Other protists move using tiny, hairlike
structures called cilia. The cilia are found on the
outside of the cell. They are able to move very
quickly back and forth, moving the protists along through water or another liquid.
Finally, some protists move using flagella. These are simple, whiplike
structures that propel the protist through its environment.
Nutrition
Some protists are producers and have chloroplasts and chlorophyll. Others
are consumers.
Is it Protista or Not?
Any organism that has these specific characteristics is a Protista. If it doesn’t
have these characteristics, it’s not a Protista.
Cell membrane – the thin layer of protein and fat that surrounds the amoeba; it
allows some substances to pass into the cell, and blocks other substances.
Contractile vacuole – a cavity within the amoeba that excretes excess water and
waste; the waste is brought to the cell membrane and is then eliminated from the
amoeba.
Cytoplasm – a jelly-like material that fills most of the cell; the organelles (like the
nucleus) are surrounded by cytoplasm.
Food vacuole – a cavity within the amoeba in which food is digested (broken down
in order to be absorbed by the amoeba).
Food being engulfed by psuedopods – the amoeba "eats" by surrounding bits of
food with psuedopods that form around the food; the amoeba then incorporates the
food into the cell, forming a food vacuole.
Nucleus – the major organelle of the amoeba, located centrally; it controls
reproduction (it contains the chromosomes) and many other important functions
(including eating and growth).
Psuedopods – temporary "feet" that the amoeba uses to move around and to engulf
food.
For the Last Time, It’s Simple: Kingdom Fungi
(Fungus)
Cell Structure
Fungi cells have a nucleus that is surrounded by a nuclear membrane. Like
protists, they are called eukaryotes. Fungi have cell organelles that help the
nucleus perform all life processes.
Number of Cells
Some fungi are single-celled organisms. Many of the members of this
kingdom are many celled.
Kinds of Movement
Fungi can’t move on their own.
Nutrition
Fungi do not have any chlorophyll. They are unable to make their own food,
therefore, they are not considered producers. They are not able to actually eat other
organisms, either. Instead, fungi are able to absorb nutrients from any other
organisms. Most fungi get their nutrition from dead or dying matter, so they are
classified as saprophytes.
Is it Fungi or Not?
Any organism that has these specific characteristics is a Fungi. If it doesn’t
have these characteristics, it’s not a Fungi.
The Amoeba
(modified from The Biology Corner – Worksheets and Lessons)
The amoeba is a protozoan that belongs to the Kingdom Protista. The name amoeba
comes from the Greek word amoibe, which means change. Protists are microscopic onecelled organisms that don't fit into the other kingdoms. The amoeba is an animal-like
protist because it moves and consumes its food (consumer). The amoeba has an unusual
way of creeping along by stretching its cytoplasm into fingerlike extensions called
pseudopodia. (The word "pseudopodia" means "false foot".) Its cell membrane is very
flexible and allows for the amoeba to change shape. Amoeba live in ponds or puddles,
and can even live inside people.
By pushing the cytoplasm toward the cell membrane, the amoeba causes its body to
extend and creep along. It is also by this method that the amoeba consumes its food.
The pseudopodia extend out and wrap around a food particle in a process call
phagocytosis. The food is then engulfed into the amoeba and digested. As the food is
digested it exists in a structure called a food vacuole.
Amoebas can cause disease. A common disease caused by the amoeba is called Amoebic
Dysentery. A person becomes infected by drinking contaminated water. The amoeba
then upsets the person's digestive system and causes cramps and diarrhea. A person is
most likely to be infected in countries where the water is not filtered or purified.
The Euglena
(modified from The Biology Corner – Worksheets and Lessons)
Euglena are one-celled organisms classified into the Kingdom Protista. All Euglena have
chloroplasts and can make their own food (they are producers). Euglena can also absorb food
from their environment; Euglena usually live in quiet ponds or puddles.
Euglena move by a flagellum (plural ‚ flagella), which is a long whip-like structure that acts like a
little motor. The flagellum is located on the front end, and twirls in such a way as to pull the
cell through the water. Color the reservoir grey and the flagellum black.
Chloroplasts within the Euglena trap sunlight that is used for photosynthesis, and can be seen as
several rod-like structures throughout the cell. Color the chloroplasts green. Euglena also
have an eyespot at the front end that detects light. This helps the Euglena find bright areas to
gather sunlight to make their food. Color the eyespot red. Euglena can also gain nutrients by
absorbing them across their cell membrane.
The Euglena has a stiff pellicle outside the cell membrane that helps it keep its shape, though
the pellicle is somewhat flexible and some Euglena can be observed scrunching up and moving in
an inchworm type fashion. Color the pellicle blue.
In the center of the cell is the nucleus, which contains the cell’s DNA and controls the cell’s
activities. The nucleolus can be seen within the nucleus. Color the nucleus purple, and the
nucleolus pink.
The interior of the cell contains a jelly-like fluid substance called cytoplasm. Color the
cytoplasm yellow. Toward the back of the cell is a star-like structure: the contractile vacuole.
This organelle helps the cell remove excess water, and without it the Euglena could take in some
much water due to osmosis that the cell would explode. Color the contractile vacuole orange.
Name ______________________________________________________ Score ____________/44
Microorganisms Questions
1. What does the word micro mean?
2. What does the word organism mean?
3. What are the six characteristics of all living things?
a.
b.
c.
d.
e.
f.
4. Where do organisms get the energy they need?
5. If I put a pumpkin seed in the ground and keep it watered, what will happen to
the seed?
6. How is a polar bear adapted to its environment?
7. What is a microorganism?
8. After you determine what the word micro means, develop a definition for each of
the following terms:
a. microclimate –
b. microfilm –
c. micrometer –
d. microsurgery –
9. What is a producer?
10. How is a consumer different from a producer?
11. What is the main source of energy for most life on Earth?
12. What is:
a. an herbivore –
b. a carnivore –
c. an omnivore –
13. If a person weighs 100 pounds, how much of that would be water?
14. Why can’t humans use ocean water directly for drinking water?
15. I have recently found a new organism. I need to classify it. I think it should be
classified as a Moneran. Look at the following characteristics and see if you agree
with me. (Circle your answer).
a. My new organisms are very tiny. When I see it in the microscope, I notice it
is only one cell.
Could this be a Moneran?
Yes
No
b. When I look closely inside the cell, I notice there is no nucleus. I don’t
notice any organelles inside the cell.
Could this be a Moneran?
Yes
No
c. This cell does not seem to be able to move. I do not notice any structures
on or I the cell that would help it move.
Could this be a Moneran?
Yes
No
d. This cell has a cell wall and chlorophyll. It is able to use the Sun’s energy
to make its own food. It does not have any cell structures that would allow it to use
other organisms for food.
Could this be a Moneran?
Yes
Is this organism a Moneran?
No
Yes
No
16. Guess what? I have found some more new organisms. I think they should be
classified as either Moneran or Protist, but I’m not sure. Look at the following
characteristics and see if you can decide which kingdom they should be in.
a. When I look at one of the organisms in the microscope, I notice a tiny
nucleus inside the cell. A membrane surrounds the nucleus.
This organism should be classified as a
Moneran
Protist
b. When I look at the next organism, I notice it has more than one cell. I don’t
see any tissues or organs, but the group of cells seems to be one organism, not a
colony.
This organism should be classified as a
Moneran
Protist
c. This organism is moving. I notice that it is a single cell, with a flagellum. I
cannot tell if this organism has a nucleus or not.
This organism should be classified as a
Moneran
Protist
Don’t know
d. This is a simple organism with chloroplasts in its cell. It makes its own
food.
This organism should be classified as a
What is this organism:
Moneran
Moneran
Protist
Protist
17. Read each of the following statements. If the statement is true for a fungus,
write “T” on the line. If it is not true, write “F” on the line.
a. _____ It may have many cells.
b. _____ It has a cell membrane.
c. _____ It may have only one cell.
d. _____ It is a eukaryote.
e. _____ It is a producer.
f. _____ It can move voluntarily.
g. _____ It is a saprophyte.
h. _____ It is a prokaryote.
i. _____ It has organelles.
j. _____ It has chlorophyll and can photosynthesize.
18. How does an amoeba move?
19. Fingerlike extensions of the amoeba's cytoplasm are called ...?
20. What disease is caused by the amoeba?
21. To what Kingdom does the amoeba belong?
22. How are protozoans classified?
Color the Euglena according to the directions. Organelles can be identified based on their
descriptions and locations. Answer the following questions
1. Are euglena unicellular or multicellular?
2. What Kingdom do euglena belong to?
Flagellum
Eyespot
3. What organelle carries out photosynthesis?
Reservoir
4. On which end is the flagellum located?
5. What is the eyespot used for?
Contractile
Vacuole
6. What is the function of the nucleus? Pellicle
7. What is the function of the contractile vacuole? What
would happen if the cell did not have this organelle?
Nucleus
Cytoplasm
Chloroplast
Nucleolus