Download Ch. 20 Protists

Chapter 20
Protists
I.
Protists are divided into 3 groups:
1. Animallike- must absorb food
2. Plantlike- make own food.
3. Funguslike
II. Protist- any organism that is not a plant, animal,
fungus or a prokaryote (no nucleus).
a. Most are unicellular (single-celled)
III. Animallike Protists
A. Zooflagellates – animal-like protists that
swim using flagella.
1. May have one or many flagella for
swimming
2. Take in nutrients through the cell
membrane.
Trophozoites (pear-shaped)
B. Sarcodines- move by temporary projections in
the cell body called pseudopods
1. Surround and engulf their food and store in
food vacuoles.
Click for movie of amoeba locomotion
C. Cilliates- Use cillia for feeding and movement
i.e. paramecium (see below)
1. cillia- short hair-like structures on the cell
membrane.
a. Usually hundreds or thousands of cillia
on one cell
2. Trichocysts- parts of the cell membrane that
can protrude and act as a defense mechanism
3. Contain 2 nuclei:
a. Macronucleus (large) - contains DNA
for day-to-day existence.
b. Micronucleus (small) - contains a
back-up copy of DNA.
IV. Reproduction in Protists- normally asexual (cloned)
a. Conjugation (sexual reproduction)- if
conditions are right two paramecium join and randomly
exchange DNA. That exchanged DNA then copies itself
and each paramecium gets the new DNA.
V. Sporozoans- can not move on their own so they
are parasitic.
a. Reproduction by means of a sporozoite which
is the sporozoan gone dormant with a protective
shell around it (like a shell for a seed)
b. Many cause disease
i.e. plasmodium falciparum- causes Malaria;
carried in the bite of an Anopheles mosquito
Plasmodium
attacking and killing
red blood cells in a
human
Life cycle of Plasmodium
Trypanosoma protist- causes African Sleeping
Sickness carried in the excretion of a tseste fly.
Dysentery (severe diarrhea) caused by Entamoeba
Cysts can easily
be killed with
proper sanitation
VI. Plantlike Protists (Unicellular)- single-celled
organisms (algae) that can make their own food
A. Euglena- almost like zooflagellates but
contain chloroplasts for photosynthesis
1. No cell wall but a ridged cell membrane
called a pellicle
2. Eye Spot – Helps find sunlight
B. Dinoflagellates- half are photosynthetic other half
are heterotrophs (must eat food)
1. Flagella stored in grooves called cingulum on
cell membrane when not in use
2. Some are luminescent and give off a bluish or
redish glow at night
C. Chrysophytes- have gold-colored chloroplasts
absorbing different colors of light than green plants
1. Golden-brown or yellowish-green in color
D. Diatoms- produce thin delicate cell walls made
of silicon etched in patterns therefore, glasslike
VII. Plant-like Protists (Red, Brown and Green;
“pondscum”)- Mostly multicellular; reproduce like
plants; have cell walls; no roots or “woody” tissue
1. 3 main groups according to the different
types of chlorophyll they have:
A. Red Algae- contain “chlorophyll a”
which is very good at absorbing blue light
therefore, red algae can live at great
depths in the ocean.
1. Red Tides- red algae overtakes an area from eating
high concentrations of nitrates from fertilizers that
have drained off the land from farming.
B. Brown Algae- “seaweed”; largest and most
complex of the algae.
1. All are multicellular
2. Have leaflike structures; look like brown vines
or ferns
C. Green Algae- “moss”; can be unicellular; live in
colonies or be multicelluar like a plant.
1. Identical to plants in almost every way except
no roots or woody tissue.
a. Unicellular- single celled
Netrium digitus
b. colonies- individual cells live together and help
each other- i.e. volvox
Volvox
c. multicellular- just like a plant; cells are
connected and have an individual job for the
whole organism. i.e. spirogyra
300x
1000x
VIII. Funguslike Protists- absorb nutrients from dead
and decaying organisms. Lack thick cell walls –is
made of chitin (kite-in) like true fungi.
A. Chitin- carbohydrate similar to that of an
insects’ exoskeleton
1. Slime Molds- unicellular amoebalike cells that live in the soil.
When nutrients run out
they form a colony that
builds a fruiting body (what you
see) that contain spores
(egglike) that the wind will
carry like a seed to new
ground.
Various Slime Molds