Download Protists, Sponges & Cnidarians

Unicellular Organisms
Objective 1.2 Identify unicellular organisms,
including bacteria and protista, by their
methods of locomotion, reproduction, ingestion,
excretion, and effects on other organisms.

There are two types of microorganisms:
Eukaryotic and prokaryotic. Let’s look at each
one.
Eukaryotic

any organism that contains specialized
organelles in the cytoplasm, a
membrane-bound nucleus enclosing
genetic material organized into
chromosomes, and an elaborate system
of division by mitosis or meiosis,
characteristic of all life forms except
bacteria, blue-green algae, and other
primitive microorganisms.
Prokaryotic

any cellular organism that has no nuclear
membrane, no organelles in the
cytoplasm except ribosomes, and has its
genetic material in the form of single
continuous strands forming coils or
loops, characteristic of all organisms in
the kingdom Monera, as the bacteria and
blue-green algae.


Right: Colorized micrograph of a prokaryotic cell of the bacterium.
Left: Colorized micrograph of a eukaryotic cell of the green algae.
Eukaryotes
Protists

Protists are an extremely diverse assortment
of eukaryotes.
Protists

Protists are more diverse than all other
eukaryotes.

No longer classified in a single kingdom.


Paraphyletic
Most protists are unicellular, some are
colonial or multicellular.
Protista/protist
A unicellular,
eukaroytic organism
belonging to the
former taxonomic
kingdom Protista.
They produce their
Nutrition in Protists
 Microorganisms
such as
prokaryotic bacteria and
eukaryotic protists need food to
survive. Some are producers
that make their own food while
others are consumers which
must take in food (ingestion)
from an external source.
Microorganism
any
organism too small to
be viewed by the unaided
eye, as bacteria, protozoa,
and some fungi and algae,
that typically consists of
only a single cell.
Ingestion
To
take in and
absorb as food
Many bacteria are decomposers that
break down dead organisms and wastes.
All organisms must get rid of wastes
through the process of excretion.
 Let’s look each type of way a organism
consumes food and get rids of waste.

consumer
an
organism, usually
an animal, that feeds
on plants or other
animals
producer
an
organism, as a
plant, that is able to
produce its own food
from inorganic
substances.
Decomposer
An
organism, often a
bacterium or fungus, that
feeds on and breaks down
dead plant or animal
matter, thus making
organic nutrients available
to the ecosystem.
Excretion
The
act or process of
discharging waste
matter from the cell.
Reproduction and Life Cycles

Reproduction is essential to the
continuation of every species. Some
organisms reproduce asexually by binary
fission. Other organisms reproduce
sexually by conjugation. Some
prokaryotic organisms produce
endospores when conditions are
unfavorable for development.
Binary fission
A method
of asexual
reproduction that
involves the splitting of
a parent cell into two
approximately equal
parts.
Conjugation
A process
of sexual
reproduction in which
ciliate protozoans of the
same species temporarily
couple and exchange
genetic material.
Endospores
A small
asexual
spore, as that formed
by some bacteria.
Locomotion
Unicellular organisms have various
modes of locomotion, or movement.
 Protists have three main methods of
locomotion.
 Let’s look at each type of
locomotion.

Locomotion
The
act of moving from
place to place: selfpropelled movement
Locomotion in Protists

Some protists, like
this Euglena, have
one or two long
flagella that they
can whip around an
propel themselves
through the water.
Flagella
a
long, lash like
appendage serving as
an organ of locomotion
in protozoa, sperm
cells, etc.
Locomotion in Protists

Some, like this
Tetrahymena, are
covered with
numerous, but
shorter, cilia that
facilitate movement
and/or feeding.
Cilia

A microscopic hairlike process extending
from the surface of a cell or unicellular
organism. Capable of rhythmical motion,
it acts in unison with other such
structures to bring about the movement
of the cell or of the surrounding medium.
Locomotion in Protists

Others use ameboid
movement to get
around.

A pseudopod is
extended forward,
followed by the rest
of the organism.
Pseudopod
A temporary
footlike
extension of a one-celled
organism, such as an
amoeba, used for moving
about and for surrounding
and taking in food.