Ch 18: Protists

Protists unicellular eukaryotic

Prokaryotes vs Eukaryotes

Classification 115,000 species Major debate regarding how they should be classified “animal-like” = zooplankton or protozoans “plant-like” = phytoplankton 

Endosymbiotic Theory It is believed that protists evolved from a symbiotic relationship between different types prokaryotic cells Chloroplasts resemble cyanobacteria Mitochondria resemble aerobic bacteria

Endosymbiotic Theory 2

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

Reproduction Like bacteria, paramecium reproduce mainly by BINARY FISSION

Paramecium Sex Again, 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 FLAGELLA Many 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 Cycle 1. Spores transferred to humans through mosquito saliva 2. 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: Sarcodina Use PSEUDOPODS to feed and move around

Ameoba