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