Protist: A new bunch of organisms…
Some questions to ponder:
- How do these animal eat?
- How do they regulate water balance?
- How do they reproduce?
- What are some characteristics that can be used for classification?
- How are different types of protists both unique and different?
- What is the advantages and disadvantages of living in fresh water?
- What is the difference between a zooplankton and a phytoplankton?
- What phylums and kingdom do all these creatures belong to?
What is new! ( Comparing Protists to Bacteria and Virus)
- Protists are eukaryotes and so have
- distinct nucleus
- membrane bound cell organelles
- unique flagella
- are single celled
- have cytoplasmic streaming
- Protist can live in a variety of environments, but are now larger so they need to regulate water balance and store and/or make food.
- Protist are more diverse in how they move, using flagellums, pseudopods and cilia and intermediate hosts.
- Some protists can change their body shape or cell membrane during their life cycle.
- Some protists can reproduce using sexual reproduction.
- Some protist, are parasitic they are called protozoans and cause diseases.
- Some protist have a silicone membranes and can glow in the dark!
- Tiny protists are the major food choice of some of the worlds largest animals.
General Protist Notes:
Where are they may found….
- Usually single cell creatures found in pond water
- Over 50,000 living species
- other locations and points of interest include:
used as a means to clean sewage
found in intestines of termites for digestion of cellulose
may be an infectious diseases such as
plasmodium… which is malaria
trympanosoma…. which is called sleeping sickness
- protist move in response to several stimuli. This movement is called Protist can respond both to light and chemical stimuli, positive phototropism allows organisms to be attracted to light. Negative tropism allows organisms to avoid harmful stimuli such as predators, low oxygen, lower temperatures and other possible harmful chemical or physical stimuli. This response ( to move away from a stimuli) is called an avoidance response.
On a historic note:
By jove! Forminifera ( type of diatom) has hard shell which are used for dating early forms of life. Protozoans also show shell like deposits, an example is the White Cliffs of Dover in England.
Form and Function:
protists are Eukaryotes so…
- usually unicellular, so no tissues yet….
- have a nucleus with a membrane
- can be motile
- can be (animal like) heterotrophic or ( plant like) autotrophic
- have complex arrary cell organelles
Classification:
Note: All protist belong to Kingdom Protista, which has four phylums.
- Mostly Autotrophs called Phytoplankton
- Phylum Euglenophyta example Euglena
- autotrophic, chlorphyll
- no cell wall
- move about with flagella
- found in fresh water and soil
- attracted to light ( positive phototropic)
- Phylum Chrysophyta: example Diatoms
- autotrophic, chlorophyll and yellow pigment ( golden algae)
- silica shell in cell wall form symetric shapes
- found in oceans
- positive phototropism
- silicas used in commercial product such as pool filters, silver polish and toothpaste
- Phylum Pyrrophyta: example Dinoflagellates
- autotrophic, chlorophyll, have red pigment which makes “red tide”
- heavy rigid cell wall
- two (dino) flagella
- found in oceans
- some species glow in dark ( bioluminescence: phenomenon of living things giving off light, have protein which converts chemical energy to ight energy.
- Mostly Heterotrophs called Zooplankton:
- Phylum Protozoa ( classified by how they move)
- usually heterotrophic
- no cell walls, usually moveable cell membrane
- can move about or live as parasite
Protozoan classification
class Sarcodinia Amoeba
class Flagellata trympanosoma and in termites
class Ciliophora Paramecium
class Sporozoa parasitic
Types of Locomotion:
flagella found in Euglena
pseudo pod found in Amoeba
(cytoplasmic streaming)
cilia found in Paramecium
A quick comparison of three protist: ( note highlighted vocabulary)
Euglena:
- for movement it uses a flagellum, which makes the Euglena very fast.
- for storing genetic material it has a nucleus and a nucleolus
which regulates protein sythesis and cell control, it is asexual in reproductive behaviour
- for energy Euglena are autotrophs and have a chlorplast, with chlorophyll which allows for photosythesis
- for storing energy pyrenoids and parmylum store starch which is a product of photosythesis
- for protection and water it has a pellicle which maintains shape and
balance allows for diffusion across cell membrane.
- Response to stimuli Euglena are attracted to light, this is call phototropism
Amoeba
- for locomotions it has extensions of cytoplasm which are called pseudopod ( false foot), so an amoeba will move very slow. Ectoplasm ( layer closest to cell membrane) is water like next to internal gel like endoplasm
- for genetic material it has only one nucleus and is asexual
- for energy it has food vacuoles which digest food with enzymes and move nutrients to
- to balance water it has contractile vacuoles, in a variety of positions within cytoplasm
.
- to maintain shape it has an inner membrane, endoplasm
and an outer membrane, ectoplasm, these two layers are needed since it is constantly changing shape.
- stimuli amoebas are attracted to food and some chemicals but move away from harmful chemicals and light. (negative tropism)
Paramecium
- for locomotion it has cilia surrounding whole body so it moves very fast.
- for genetic information there is a micronucleus to controls sexual reproduction, ( it divides during conjugation)and a macronucleus to control cell functions.
- for feeding it has a “mouth” called an oral groove and a mouth pore
- for digestion it has a gullet which is like a stomach, which forms food vacuoles
- for removal of food waste there is an anal pore
- for water balance there is a contractile vacuole
- for shape there is a distinct cell membrane, a rigid pellicle which holds cells shape.
- for stimuli there are small “spears” call trichocyst which serve as a form of protection or hunting for food.
- Ways to compare Zooplankton:
| Function or Structure | Euglena | Amoeba | Paramecium |
| Locomotion
(structure) |
Flagellum | Pseudopod | Cilia |
| Speed of locomotion | Moderately Fast | Very Slow | Very fast |
| Nutrition or digestion | autotroph
manufactures own food with chlorphyll |
heterotroph
engulfs food at any point of cell membrane. Digests via food vacuoles |
heterotroph
uses oral groove or gullet to suck in food (cyclosis) |
| Respiration or gas exchange | Diffusion through cell membrane | Same | Same |
| Excretion of liquids and water balance | Contractile vacuole in definite position | contractile vacuole may vary in position | two contractile vacuoles in definite position |
| Excretion of solids | Through reservoir | Pushed through membrane at any point | Has an anal pore |
| Excretion of gaseous wastes | Diffuse through cell membrane or through contractile vacuole if dissolved in fluid | same | same |
| Reproduction | asexual via binnary fission | asexual by binnary fission
may form cysts |
asexual binary fission
sexual via conjugation |
| Shape | definite shape | ||
| Behaviour | responds to light, called phototrophic
|
+ to food and chemicals
– to light |
+ to food and chemicals
– to trichocysts |
The Amoeba
has
a nucleus
granular cytoplasm
vacuoles
semi-permeable membrane
engulfs food by using pseudopod
Other species
Forminifera
Radiolaria
Bacillaria
The Paramecium
member of class called the ciliates
has
cilia for locomotion
feeds through funnel like gullet
has 2 nuclei, reproduction through binary fission
for every single cell, 8 new ones are created
contractile vacuole controls water balance
sexual reproduction by conjugation
Protist are:
single cell
complex
can be in colonies ( example: Volvox..has up to 5000 cells in it)
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