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Paramecium
Animal-like Protists
Animal—like protists cannot make their own
food and must feed on things that are living
or were once alive. They have all of the
organdIes of an animal cell, and, like
etiglena, they have a contractile vacuole.
Amoeba
As the amoeba moves, it changes shape
(Figure 5). These bloblike organisms move by
stretching out a branch of cytoplasm, called a
pseudopod (false foot). The pseuclopod
anchors to an object, and the rest of the cell is
dragged toward it. This method of movement
is also used by animal white blood cells,
including the ones in your blood vessels. The
Tb e param cci till) (plural /nna liter/a.), like
the amoeba, uses structures designed for
fllovei)lCnt to help it feed (Figure 6). Tiny
hairlike structures, called cilia, beat together
to create water currents that move the
paramecium. There are also cilia around the
paramecium’s oral groove. These cilia draw
food into the groove. Bacteria and other
smaller cells arc the main food source
for paramecia.
oerfo-ms.
macronucleus
contains genetic material
that regulates cell function
micronucleus
contains genetic information
that is exchanged between
para’ec a dur ng reproduct:on
food vacuole
Where food is
slowly digested
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gullet
A cavity at the end of the oral
groove. Hee :he food enters
pseudopod
contractile vacuole
Pumps out excess water;
prevents the paramecium
from bursting
oral groove
Lined wirn cilia that
sweep in food
Fungus
Ftingi (singtilarf’hngu.s) incltide many organisms th;tt
are in ul ticel I tiiar. Bread mould, in ush rooms, and puff
balls are well—known fungi. iiarmftil fungi incitide those
that cause ringworm. Dutch elm disease, and athlete’s
foot. l-lowever, there are some unicellular fungi.
amoeba is a single
O The
armai cell. It feeds by
wrappng itself around foco.
food
vacuole
\t’ast is one of the few tinicelltilar ftingi (Figure 7).
There are many different species of yeast. Like animal
cells, yeast cells do not have chlorophyll and must rely
on other organisms for their source of energy.
s ow y engul’s food
0 Amoeba
particles by extending its
oseudopods.
inside the vacuole.
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Unit I
.
8. What effect do chemicals such
as caffeine have on unicellular
organisms? State your hypothesis,
and design an experiment to test it.
With your teacher’s approval,
conduct your experiment.
j2sign Challenge
Yeast, the Unicellular Fungus
membrane around the food forms
0 The
a food vacuole. Digestion takes place
microorganisms with disease?
6. Using the information that you have
gained about osmosis, indicate why
euglena, paramecia, and amoebas
need contractile vacuoles.
7. Penicillin is an antibiotic that
weakens the cell wall of bacteria.
The sugars and proteins in the
cytoplasm of the bacteria are in
higher concentration than they are
in their environment. Draw a series
of diagrams showing how penicillin
kills bacteria.
Exploring
a fooc vacjoe.
food
‘4
4
5. Why do many people associate
1
‘1
i
contra ctile
vacuole
1. Why do you think bacteria are
considered to be more primitive
than other cells that you have
studied?
2. Why are diatoms called plantlike
protists?
3. Compare euglena to a plant cell.
Make a list of similarities and
differences.
4. Compare the process of feeding
in the paramecium and amoeba.
Making Connections
‘if’
/
nucleus
unct:ons that yo body
anal pore
Expels waste
Hairlike structures
V’at beat togetr.er
to move water
The amoeba crawls and feeds
at the same time,
Understanding Concepts
singe amma
cel! tnat must perform most of te
‘‘“
crawling motion of the amoeba is also used
for feeding
cilia
bJ!ihi3.l
The pwamecium is aiso a
Using a microscope,
it is difficult to tell
that yeast are living,
There are cells in the :ubes that lead
to your lungs that have cilia much like
those of paramecium. Human white
blood cells, Pike amoeba, engulf and
digest foreign particles. Examine the
structures of the unicellular organisms
carefully. Would any of these features
be useful in your model cell? Consider
looking to primitive cells for
assistance with your Challenge.
Cr’U. ?‘is ii,’s. (hrun s, and .S.clnns
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