Bellringer
Have you ever hear of a protist before? How
many examples of protists can you think of? Why
do you suppose protists are not as well known as
fungi?
Record your answers in your science journal.
General Characteristics
• A protist is a member of the kingdom
Protista. Most protists are single-celled
organisms, but some are made of many
cells, and others live in colonies.
• Eukaryotic Organisms All protists are
eukaryotic, which means that their cells
each have a nucleus.
 Single
celled or multi-celled
 Autotroph or heterotroph
 How they move
 How they reproduce
 Producers
 Decomposers
 Parasites
 Heterotrophs
Protists and Food
• Producing Food Some protists are
producers.
•Like green plants, these protists
make their own food through
photosynthesis. They are known as
autotrophs.
• Finding Food Some protists must
get food from their environment.
•These protists are heterotrophs.
Heterotrophs are organisms that
cannot make their own food.
• Some protists are decomposers.
Decomposers get energy by breaking
down dead organic material.
• Some protists are parasites. A
parasite invades another organism to
get the nutrients it needs. The
organism that a parasite invades is
called a host.
•
Asexual Reproduction Most protists reproduce
asexually. In asexual reproduction, the offspring
come from just one parent.
•
•
Fission – where one parent divides into two identical
copies
Sexual Reproduction Some protists can
reproduce sexually. Sexual reproduction requires
two parents.
•
Conjugation – Two individuals join together and
exchange genetic material using a small second nucleus.
Producing More Protists, continued
• Many protists can reproduce asexually and
sexually. In some protist producers, the kind of
reproduction alternates by generation.
• For example, a parent will reproduce asexually,
and its offspring will reproduce sexually.

Complex Reproductive cycles –

Some protists have complex reproductive cycles.
These protists may change forms many times. The
next slide shows the life cycle of Plasmodium vivax,
the protist that causes the disease malaria.
Bellringer
Do you know what algae is? Have you ever seen it?
What does it look like? Algae needs a lot of water in
order to live. Where do you suppose most algae live?
Record and illustrate your answers in your science
journal.
•
•
Scientist place protists into three groups based on their
shared traits: producers, heterotrophs that can move,
and heterotrophs that can’t move.
Many protists are producers. Like
plants, protist producers use the sun’s
energy to make food through
photosynthesis. These protist producers
are know as algae.
•
•
Some algae are made of many cells and generally live
in shallow water along the shore. You may know these
algae as seaweeds.
Phytoplankton are the microscopic
algae that float near the surface of marine
or fresh water.
•
•
Red Algae Most of the world’s
seaweeds are red algae and live in
tropical oceans, attached to rocks or to
other algae.
Green Algae The green algae are the
most diverse group of protist producers.
Most live in water or moist soil. But
others live in melting snow, on tree
trunks, and inside other organisms.
•
•
Brown Algae Most of the seaweeds
found in cool climates are brown algae.
They attach to rocks or form large
floating beds in ocean waters.
Diatoms are single celled. They are
found in both salt water and fresh water
and make up a large percentage of
phytoplankton.
•
Dinoflagellates have two whiplike
strands called flagella. The beating of
these flagella causes the cells to spin
through the water.
•
Most dinoflagellates live in salt water, but some live
in fresh water or snow.
•
Euglenoids are single-celled protists and
live in fresh water.
•
•
Many euglenoids are producers, but can also get
food as heterotrophs.
Other eugelnoids are full time consumers or
decomposers.
•
•
Heterotrophic protists that can move are
often called protozoans.
Amoebas and similar amoeba-like
protists are soft, jellylike protozoans.
They are found in both fresh and salt
water, in soil, and as parasites in animals.
•
Although amoebas look shapeless, they are highly
structured cells.
•
•
Amoebic Movement Amoebas and
amoeba-like protists move with
pseudopodia. Pseudopodia means “false
feet.” Amoebas and amoeba-like protists
use pseudopodia to catch food, too.
Shelled Amoeba-Like Protists Not all
amoeba-like protists look shapeless.
Some have an outer shell.
•
Zooflagellates Flagellates are protists that
wave flagella back and forth to move. Some
flagellates live in water. Others live in the
bodies of other organisms.
• Ciliates Ciliates are complex protists.
They have hundreds of tiny, hairlike
structures known as cilia. Ciliates use
their cilia for movement and also for
feeding. The best-known genus of ciliates
is Paramecium.
•
Some protist heterotrophs are parasites that do not
move about. Others can only move at certain phases of
their life cycle.
•
Spore-Forming Protists Most spore-forming protists
are parasites. They absorb nutrients from their hosts.
Spore-forming protists have complicated life cycles
that usually include two or more hosts.
• Water Molds live in water, moist soil, or other
organisms. Some of them are decomposers and thus
eat dead matter. But many are parasites.
• Slime Molds can move only at certain phases of
their life cycle. Live in cool, moist places in the
woods. They use pseudipodia to move around. But
when environmental conditions are stressful, they
form spores that cannot move.
Bellringer
Many people love to eat mushrooms. What are
mushrooms? There are many different types of
edible mushrooms. How many can you name that
you’ve eaten? How many mushrooms can you
name that are available at your grocery store to eat?
Record your answers in your science journal.
• Fungi are eukaryotic heterotrophs that have rigid
cell walls and no chlorophyll. They are so different
from other organisms that they are placed in their
own kingdom.
• Food for Fungi Fungi cannot catch or surround
food. Fungi must live on or near their food supply.
Most fungi are consumers, but some are decomposers
and others are parasites.
Characteristics of Fungi, continued
• Hidden from View
Multicellular fungi are
made up of chains of
cells called hyphae.
Most of the hyphae
grow together form an
underground mass
called the mycelium,
which makes up the
major part of the
fungus.
Characteristics of Fungi, continued
• Making More Fungi Reproduction in fungi may
be either asexual or sexual.
• In one type of asexual reproduction, the hyphae
break apart, and each new piece becomes a new
fungus.
Characteristics of Fungi, continued
• Asexual reproduction can also take place by
the production of spores. Spores are small
reproductive cells that are protected by a thick
cell wall. When the growing conditions are
right, a spore will grow into a new fungus.
• Sexual reproduction in fungi happens when
special structures form to make sex cells. The
sex cells join to produce sexual spores that
grow into a new fungus.
Kinds of Fungi
• Fungi are classified based on their shape and the
way that they reproduce.
• Threadlike Fungi Most threadlike fungi live in the
soil and are decomposers. However, some threadlike
fungi are parasites. Molds are a threadlike fungi.
• Threadlike fungi can reproduce asexually or
sexually.
Kinds of Fungi, continued
• Sac Fungi are the largest group of fungi. Sac fungi
include yeasts, powdery mildews, truffles, and
morels.
• Sac fungi can reproduce both asexually and sexually
during their life cycles. Most of the time, they use
asexual reproduction.
Kinds of Fungi, continued
• Club Fungi Mushrooms belong to a group of
fungi called club fungi. Club fungi reproduce
sexually. During reproduction, they grow special
hyphae that form clublike structures.
• Nonmushroom Club Fungi Mushrooms are not
the only club fungi. Bracket fungi, puff-balls, smuts,
and rusts are also club fungi.
Lichens
• A lichen is a combination of a fungus and an alga
that grow together. The alga actually lives inside the
protective walls of the fungus.
• Unlike fungi, lichens are producers. The algae
produce food through photosynthesis. And unlike
algae, the fungi keeps the lichen from drying out.
Lichens are found in almost every land environment.