Transcript The Kingdom Protista

The Kingdom Protista
Unit VI
Chapter 20
What is a Protist?

A protist is any organism that is not a
plant, an animal, a fungus, or a prokaryote
Protists are eukaryotes that are not
members of the kingdoms Plantae,
Animalia, or Fungi
 The 1st eukaryotic organisms on Earth,
appearing nearly 1/5 billion years ago,
were protists
 Protists are a diverse group that may
incloude more than 200,000 species

Classification of Protists

Most protists are classified by their method
of obtaining nutrients

Animal-like protists are heterotrophs

Plant-like protists photosynthesize

Fungus-like protists are parasites or
decomposers
Animal-Like Protists: Protozoans

The 4 phyla of animal-like protists are
distinguished from one another by their
means of movement:
1.
2.
3.
4.
Zooflagellates – swim with flagella
Sarcodines – move by extensions of
cytoplasm
Ciliates – move by means of cilia
Sporozoans – do not move on their own
Zooflagellates

Animal-like protists that swim using flagella
are classified in the phylum Zoomastingina
and are referred to as zooflagellates

Most have either 1 or 2 flagella (although
some species have many)
Zooflagellates

Absorb food through their cell membranes

Most live in lakes and streams, although
some live in the bodies of other organisms

Most reproduce asexually by means of
binary fission, although some have a
sexual life cycle
Sarcodines

Sarcodines are animal-like
protists that use pseudopods
for feeding and movement


Pseudopods (false feet)
are temporary projections of
cytoplasm
The best known sarcodines
are amoebas
• Amoeboid movement
involves the cytoplasm of the
cell streaming into the
pseudopod allowing the rest of
the cell to follow
Sarcodines

Amoebas can capture
and digest particles of
food and even other cells
• To do this, they surround
their meal and take it
inside to form a food
vacuole (a small cavity in
the cytoplasm that
temporarily stores food)

Amoebas reproduce by
means of binary fission
Ciliates

Animal-like protists that move and feed by
means of cilia are known as ciliates



Cilia are hair-like projections similar to flagella
Most ciliates are free living (non parasitic)
Some of the best known ciliates belong to the
genus Paramecium
Ciliates – Internal Anatomy
of the Paramecium







The cilia of a paramecium are organized into evenly spaced
rows and bundles that beat in an efficient pattern
A paramecium’s cell membrane has trichocysts
 small, bottle-shaped structures used for defense
Paramecium have a macronucleus
 a working library of genetic information
Paramecium have a micronucleus
 contains a reserve copy of all of the cells genes
Paramecium have a gullet
 An indention in one side that traps food particles
Paramecium have an anal pore
 Region of the cell membrane used to empty waste materials
into the environment
Paramecium have contractile vacuoles
 Used to collect and store excess water
Ciliate Reproduction

Under most conditions,
ciliates reproduce
asexually by mitosis and
binary fission
However, when placed
under stress, cilia may
engage in conjugation
 During conjugation, 2
cilia attach themselves
to each other and
exchange genetic
information

Sporozoans

Members of the phylum Sporozoa are
animal-like protists that do not move on
their own and are parasitic
• The sporozoan Plasmodium, which causes
malaria, is carried by the female Anapheles
mosquito
• As many as 2 million people die from malaria
each year
• Other diseases caused by animal-like protists
include: African Sleeping Sickness and Giardia
Plant-Like Protists: Unicellular Algae

The 4 phyla of plant-like protists that
are grouped together as unicellular
algae are:
1.
2.
3.
4.
Euglenophytes
Dinoflagellates
Chrysophytes
Diatoms
Chlorophyll & Acessory Pigments

One of the key characteristics used to
classify algae is the type of photosynthetic
pigments they contain
• In adapting to conditions of limited light, various groups
of algae have evolved different forms of chlorophyll
• Chlorophyll a
• Chlorophyll b
• Chlorophyll c
• Each form of chlorophyll absorbs different wavelengths
of light
• Many algae also have accessory pigments that
absorb light at different wavelengths than
chlorophyll
Euglenophytes




Euglenophytes are plantlike protists that have
two flagella but no cell wall
Euglenas have a cluster of reddish pigments
known as an eyespot which function to help
find sunlight for photosynthesis
Euglenas do not have a cell wall, but they do
have an intricate cell membrane called a
pellicle
Euglenas reproduce asexually by means of
binary fission
Euglenophytes
Dinoflagellates

Dinoflagellates are plant-like organisms that can be
photosynthetic or heterotrophic
 Most have 2 flagella wrapped around in grooves between 2
thick plates of cellulose that protect the cell
 Most reproduce asexually by binary fission
 Many species are luminescent
Chrysophytes

Members of the phylum Chrysophyta are a
diverse group of plantlike protists that have
gold-colored chloroplasts
• Includes yellow-green algae and golden-brown
algae
• Reproduction can be sexual or asexual
Diatoms

Diatoms are plant-like protists that
produce thin, delicate cell walls rich in
silicon (the main ingredient in glass)
Diatoms are among the most abundant
organisms on Earth
 Diatoms are beautiful!

Algal Blooms

Euglenophytes and other protists can
grow rapidly in areas where sewage is
discharged.
These rapid growths are known as algal
blooms
 Algal blooms quickly deplete the water of
nutrients, and the cells of the bloom begin
to die in great numbers
 The decomposition of these dead algae
can rob water of its oxygen, choking its
resident fish and invertebrate life

Red Tides

Great blooms of the
dinoflagellates have
occurred in recent
years on the east
coast



These blooms are
known as “red tides”
These species release
a potentially harmful
toxin that infect certain
shellfish
Eating these infected
shellfish can be
harmful or fatal
Plant-Like Protists: Red, Brown,
and Green Algae

The 3 phyla of
algae that are
largely multicellular
are commonly
known as red algae,
brown algae, and
green algae

A major difference
among these phyla
are their
photosynthetic
pigments
Red Algae

Red algae are plant-like protists that are
members of the phylum Rhodophyta


Red algae are able to live at great depths due to
their efficiency in harvesting reddish accessory
pigments called phycobilins


Meaning “red plants”
Phycobilins absorb blue light, enabling red algae
to live deeper in the ocean
Most red algae are multicellular and can live in
waters from the polar regions to the tropics

Example: Chondrus crispus (irish moss)
Red Algae
Chondrus crispus
(Irish moss)
Brown Algae

Brown algae are plant-like protists that
belong to the phylum Phaeophyta

Means “dusky plants”
Brown algae contain chlorophyll a and c,
as well as a brown accessory pigment,
fucoxanthin
 All brown algae are multicellular and most
live in cool, shallow, coastal marine waters


Examples: giant kelp, Sargassum, and
Fucus
Brown Algae
Giant kelp
Green Algae

Green algae are members of the phylum
Chlorophyts


Green algae share many characteristics with
plants, including their photosynthetic pigments
and cell wall composition




Means “green plants”
Have cellulose in cell wall
Contain chlorophyll a and b
Store food in the form of starch
Green algae can be found in fresh or salt water



Some are single cells (ex: Chlamydomonas)
Some form colonies (ex: Volvox)
Some are multi-cellular (ex: Ulva)
Green Algae
Chlamhydomonas
Volvox
Ulva
unicellular
colonial
multicellular
green algae
green algae
green algae
Human Uses of Algae
Ice creams
 Salad
dressings
 Plastics
 Waxes
 Deodorants
 Paints
 Agar

Fungus-Like Protists

Fungus-like protists are heterotrophs that
absorb nutrients from dead or decaying
organic matter


Unlike true fungi, however, funguslike
protists have centrioles and lack chitin in
their cell wall
The fungus-like protists include:
Cellular slime molds
 Acellular slime molds
 Water molds

Slime Molds

Slime molds are fungus-like protists that
play key roles in recycling organic material


They are found in damp places that are rich
in organic matter, such as forest floors
The 2 groups of slime molds are:
Cellular slime molds (individual cells
remain distinct)
 Acellular slime molds (cells fuse to form
larger cells during some life cycle phases)

Cellular Slime Molds

Cellular slime molds
belong to the phylum
Acrasiomycots

Individuals can form
large slug-like
colony that
functions as a
single unit during
harsh times
Acellular Slime Molds

Acellular slime molds
belong to the phylum
Myxomycota

During the course of
their life cycle, their
cells fuse to produce
structures with many
nuclei known as
plasmodia
Water Molds

Water molds
are members
of the phylum
Oomycota

They thrive
on dead or
decaying
organic
matter in
water and are
plant
parasites on
land