Note: This lesson is assessed in the Microscope Internal but not the External Exam. 3. Single Celled Organisms. Describe the structure of a variety of single celled organisms and the functions of their organelles. Unicellular Organisms. - Unicellular (one 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
-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.
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.
-lives in fresh water, and are
especially common in warm seasons,
when they populate drainage ditches
and range in size from 1/1000 to
1/100 of an inch (0.025 to 0.254 mm)
-Most species are green, because they
contain chloroplasts, which allows
them to produce their own food. They
serve as primary producers in many
-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.
Hibernation: when conditions are bad
(dry or too hot/cold)
Euglena forms into a sphere, called the palmelloid
Each euglena then discards its
flagellum, and forms a mucus
Each euglena first creates two of everything,
then splits evenly into two halves.
Protists, often called “slipper protists”
because of their shape like a bedroom
-usually less than 0.01 inches (.25mm)
in length, and covered with very small
hair like projections called cilia.
-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
Paramecium have two
ways to reproduce.
This type of reproduction does NOT
involve the swap of genetic material, and
makes a clone of the parent.
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
This will lead to genetic variation within
the population of paramecium.
-Amoeba possess a very flexible cell
membrane, and constantly moving
-moves by “pouring” cytoplasm into
extensions of the cell membrane,
changes as new pseudopodia are
created, and others disappear.
Eats by surrounding its prey with
pseudopods, and slowly engulfing it.
This is called phagocytosis.
Amoeba feeding sequence
Cilia – Hair like extensions of the cell membrane that contain microtubules. They are used to propel the organism throguh water in unicellular organisms.