ch 18: protists. protists unicellular eukaryotic
TRANSCRIPT
Ch 18: Protists
Protists
unicellular
eukaryotic
Prokaryotes vs Eukaryotes
Classification115,000 species
Major debate regarding how they should be classified
“animal-like” = zooplankton or protozoans
“plant-like” = phytoplankton
Endosymbiotic TheoryIt is believed that protists evolved from a symbiotic relationship between different types prokaryotic cells
Chloroplasts resemble cyanobacteria
Mitochondria resemble aerobic bacteria
endosym.theory tutorial animation
Photosynthetic prokaryote
(Some cells)
Chloroplast
Mitochondrion
Photosynthetic eukaryotic cell
Aerobic heterotrophic prokaryote
endosymbiosis generated mitochondria and chloroplasts
Anaerobic-lacking oxygen; referring to an organism, environment or cellular process that lacks oxygen and may be poisoned by it
Aerobic cellsuse oxygen to release energyfrom organic molecules by cellular respiration
-Proteobacteria
Cyanobacteria
endomembrane system evolved from inward folds of the plasma membrane of a prokaryotic cell
DNA Plasma membrane
Cytoplasm
Ancestral prokaryote
Endoplasmic reticulum
Nuclear envelope
Nucleus
Cell with nucleus and endomembrane system
Animal-like Protists
4 phyla:
Ciliophora (ciliates)
- Paramecium
Zoomastigina (zooflagellates)
Sporozoa – Parasitic - Plasmodium
Sarcodina - ameoba
Phyla #1. Ciliophora – Ciliates
Covered in cilia used for locomotion and for directing food into the oral cavity
Most are free-living (not parasites)
Ex: Paramecium
Structure 1. Pellicle – cell membrane and underlay (looks quilt-like) controls entry and exit from the cell
Embedded in the pellicle are the:
2. Trichocysts – spiny projectiles used for protection
3. Macronucleus – controls cell’s activities
4. Micronucleus – used in conjugation to mix the genetic information
5. Gullet (mouth). Cilia move food particles to the end of the gullet where they enter the cell by endocytosis. This traps the food particles into FOOD VACUOLES.
The food vacuoles will fuse with LYSOSOMES (sacks of digestive enzymes) and be digested.
ENDOCYTOSIS
6. Anal pore: Waste particles leave the cell by exocytosis at the ANAL PORE
Exocytosis
7. Contractile Vacuoles
Paramecium live in FRESH water
Osmosis causes water to move into the paramecium
The contractile vacuole collects the extra water so that the paramecium doesn’t lyse
Osmosis Review
ReproductionLike bacteria, paramecium reproduce mainly by BINARY FISSION
Paramecium SexAgain, like bacteria, paramecium will occasionally engage in conjugation – usually when they are stressed.
Conjugation is not actually “reproduction” – it is a trading and mixing of genetic material but no new paramecium are formed. However, new combinations of genes are created in both partners
Phyla #2: Zoomastigina
Called the zooflagellates since they all move around using FLAGELLAMany are parasitic
Trichomonas causes intestinal and veneral diseases in humans
Giardia – causes “beaver
fever”
Phyla #3: Sporozoa
All produce spores
All are parasites
All non-motile
Ex: Plasmodium (causes malaria)
Sporozoa
Plasmodium Life Cycle1. Spores transferred to humans through mosquito saliva2. Spores grow in liver and blood cells, causing them to lyse, releasing toxins (creates fever, chills)
3. Mosquitoes pick up Plasmodium in the blood when it bites the human
4. Mosquitoes become infected with Plasmodium – eventually, spores form in the salivary glands and the parasite is passed on to a new human
How to Avoid Malaria
1. Don’t go where there are malaria outbreaks
2. In areas where there is malaria, don’t get bit by mosquitoes
3. Chloroquinine will destroy some Plasmodium spores
4. Most often, countries with malaria try to control the mosquito host rather than the Plasmodium (insecticides and breeding ground removal)
Phyla #4: SarcodinaUse PSEUDOPODS to feed and move around
Ameoba