1. 3. Single Celled Organisms
Note: This lesson is assessed in the Microscope Internal but not the External Exam
Describe the structure of a variety of single celled organisms and the functions of their organelles
3. Single Celled Organisms

2. Unicellular Organisms
-Unicellular (one celled) organisms
are good models for membrane
transport, because they need to
perform many functions with one cell,
rather than many types of cells.

3. Unicellular organisms possess a high
degree of complexity for one cell.
Note: multicellular organisms have many cells, but each type performs one basic function. The interaction of the cells allows a multi-celled organism to live.

4. There are 3 main types of unicellular organisms
Euglena
Paramecium
Amoeba
You will be given diagrams of these three organisms.
Use the slides following to label and take notes about the functions of their organelles.

5. Euglena: a genus of microscopic organisms in the Protista Kingdom.
Some Common Unicellular Organisms
Euglena: a genus of microscopic
organisms in the Protista Kingdom.
-lives in fresh water, and are
especially common in warm seasons,
when they populate drainage ditches
and ponds.

7. -Euglena has a spindle-shaped body,
and range in size from 1/1000 to
1/100 of an inch (0.025 to mm)
long.
-Most species are green, because they
contain chloroplasts, which allows
them to produce their own food. They
serve as primary producers in many
aquatic ecosystems.

8. -Some species also eat small particles of food.
-moves via a flagellum, which is a whip-
like appendage that sticks out of the body.
-some Euglena also have a specialized
“eye spot”, which serves as a light sensor,
directing them toward available light.

9. Chloroplasts
Flagellum

10. Euglena Hibernation/Reproduction
Hibernation: when conditions are bad
(dry or too hot/cold)
Euglena forms into a sphere, called the palmelloid
stage.
Each euglena then discards its
flagellum, and forms a mucus
outer covering.

11. Euglena undergo reproduction called
“binary fission”
Each euglena first creates two of everything,
then splits evenly into two halves.

12. 2) Paramecium: another genus of
Protists, often called “slipper protists”
because of their shape like a bedroom
slipper.
-usually less than 0.01 inches (.25mm)
in length, and covered with very small
hair like projections called cilia.

14. Cilia are used in movement, and during feeding.
-Paramecium does NOT have chloroplasts
so therefore is a strict consumer.
-It eats small particles of food or bacteria
from fresh water where it lives.
The most common paramecium is
Paramecium caudata, which is used for
research

15. Paramecium Reproduction
Paramecium have two
ways to reproduce.
                                                                
They can reproduce
Asexually, and split
into two (binary fission)
This type of reproduction does NOT
involve the swap of genetic material, and
makes a clone of the parent.

16. 2) The second form of reproduction is
called conjugation, and involves the
paramecium swapping genetic material.
This type of reproduction
does not result in a clone,
but an individual with a
new set of genetic
instructions.
This will lead to genetic variation within
the population of paramecium.

17. 3) Amoeba:one of the simplest of the
protists.
-Amoeba possess a very flexible cell
membrane, and constantly moving
cytoplasm.
-moves by “pouring” cytoplasm into
extensions of the cell membrane,
called pseudopodia.

18. -the shape of the amoeba continually
changes as new pseudopodia are
created, and others disappear.
Eats by surrounding its prey with
pseudopods, and slowly engulfing it.
This is called phagocytosis.

19. Amoeba Anatomy

21. 2 1
Pseudopods 3 4
Amoeba feeding sequence

22. New organelles
Contractile vacuoles – used to pump excess water out of the cells – they collect the water from the cytoplasm and excrete it through pores.
YGU

23. Cilia – Hair like extensions of the cell membrane that contain microtubules. They are used to propel the organism throguh water in unicellular organisms.

24. Recap Quiz Which organism is a producer?
Which organism moves by pouring cytoplasm into extensions of its body?
What is phagocytosis?
What does a paramecium feed on?
How do paramecium reproduce?