1. Biology II
Chapter 20 Protista

2. Questions To Be Answered
What characteristics put an organism in the protist kingdom?
What are the four major groupings within this kingdom?
What are the names of the main organisms and why are they important?

4. Chapter 20 Protozoa
20-1 Overview of Protozoa
20-2 Protozoan Diversity

5. Section 20-1 Overview of Protozoa
Characterisitcs of Protozoa
Reproduction
Classification
Adaptations
Evolution
Great Discoveries
Paramecium

6. Characteristics of Protozoa
Single-celled, microscopic
Eukaryotes
Able to move independently
65,000 species identified
Stentor

7. Characteristics of Protozoa
Inhabit many environments –
Salt and fresh water
Soil
In bodies of other organisms (parasitic with complex life-cycles)
Heterotrophic: obtain nutrients by ingesting small molecules or cells and digest it in a food vacuole that contains digestive enzymes.

8. Characteristics of Protozoa
Zooplankton: a population of organisms that constitute one of the primary sources of energy in aquatic ecosystems.

9. Reproduction
Asexual reproduction by binary fission: divides into 2 essentially identical individuals
Some by multiple fission: cell division that results in a number of identical individuals

10. Reproduction
Sexual reproduction in the form of conjugation: individuals from opposite mating strains pair and exchange genetic material.

11. Classification
Protozoa are members of Kingdom Protista along with algae, slime molds, and water molds

12. Classification
Research into evolutionary relationships is constantly yielding new information and altering Protistan classification

13. Classification
Sometimes classified into 4 phyla based on means of locomotion
Sarcodina (Sarcodines) – pseudopodia
Ciliophora (Ciliates) – cilia
Zoomastigina (Zooflagellates) – flagella
Sporozoa (Sporozoans) – non-motile adults

14. Adaptations
Many species have physiological mechanisms for monitoring conditions in their environment
Eyespot: localized region of pigment that detects changes in the quantity and quality of light.
Others can sense physical and chemical changes or obstacles in their environment

15. Adaptations
Cyst: a dormant form characterized by a hardened external covering in which metabolic activity has ceased.
Form in response to nutrient deficiency, drought, and decreased oxygen concentration, or pH or temperature changes.
Emerge when conditions improve

16. Evolution
First life forms 3.5 billion years ago were prokaryote (bacteria), then 1.5 billion years ago the first eukaryotic organisms evolved. Protozoa are the descendants of these early eukaryotes

17. Evolution
Probably evolved through endosymbiosis: a process in which one prokaryote lives inside another and gradually both host and guest become dependent on one another.

18. Great Discoveries: The Origin of Eukaryotic Cells
Lynn Margulis -Symbiosis of Cell Evolution
Animation/tutorial

19. Mitochondria and chloroplasts are:
Self-dividing
Approximately the same size as prokaryotes
Able to make proteins and lipids
DNA within are similar to bacteria DNA rather than eukaryotic DNA
Ribosomes within are more similar to those in prokaryotes in size and are sensitive to antibiotics like bacteria
Synthesize protein using metabolic steps that bacteria use
Chloroplast produce energy in the same way that some bacteria produce energy

20. Great Discoveries: The Origin of Eukaryotic Cells
Kwang Jeon: infected a species of amoeba with bacteria parasite. Cultured amoebas that survived infection, producing a line of amoebas dependent on the bacteria for survival.

21. Protozoan Diversity Phylum Sarcodina Phylum Ciliophora
Phylum Zoomastigina
Phylum Sporozoa

22. Phylum Sarcodina 40,000 species – 100’s of species of amoebas
Inhabit fresh water, salt water, soil
Ex. Pelomyxa carolinensis – live on mud and rocks in shallow, slow-moving streams or ponds.

23. Pseudopodia
Large, rounded cytoplasmic extensions (flexible cell membranes) that function in movement.
Forms when the endoplasm (inner portion of cytoplasm) pushes the ectoplasm (outer portion) forward to create a blunt arm-like extension.
Other pseudopodia retract and cytoplasm flows in direction of new pseudopodium

25. Referred to as ameboid movement: a form of cytoplasmic streaming
Pseudopodia also used for feeding – engulf other Protists by phagocytosis – surrounds food with its pseudopodia and a portion of the cell membrane then pinches together and encloses the food vacuole in a process called endocytosis, then enzymes from the cytoplasm enter vacuole and digest the food.
Wastes leave cell in reverse process called exocytosis.

27. Contractile vacuole An organelle that expels fluid from the cell.
Freshwater organisms are usually hypertonic relative to their environment so water continually diffuses into them.
To maintain homeostasis, it must use contractile vacuole to rid cell of excess water.

28. Ecological Role: Foraminifera and Radiolarians
Test: protective shell made of calcium carbonate (foraminifera) or silicon dioxide (radiolarians). Slender pseudopodia extend through opening in test.
Foraminifera and Radiolarians

29. Radiolarians formed a type of rock called chert
Existed since Precambrian times leaving an excellent fossil record. Tests of dead organisms have been sinking to the bottom of the ocean for millions and millions of years.
Foraminifera have built up a calcium-rich layer of sediment that has created limestone and chalk deposits. Ex. White Cliffs of Dover, England and the Great pyramids of Egypt
Radiolarians formed a type of rock called chert

30. Human Diseases from Sarcodina
Most are free-living, some live in the intestines of humans or other animals
Entamoeba histolytica (amoebic dysentery):
Enters body via contaminated food and water.
Lives in the large intestine and secretes enzymes that attack the intestinal lining and cause deep ulcers.
Affected individuals feel intense pain and complications arise when amoebas are carried by blood to the liver and other organs.

31. Phylum Ciliophora 8,000 species
Paramecium
8,000 species
Swim by means of cilia – short, hair-like cytoplasmic projections that line the cell membrane.
Example: Paramecium: abundant in ponds, slow-moving streams that contain plants and decaying organic matter

32. Phylum Ciliophora
Zoothamnium
Cilia: beat in synchronized strokes that pass waves across the cell causing the protozoan to rotate on its axis.
Feed on bacteria, algae, and other small organisms found in marine and fresh water habitats.

33. Internal Structure
Pellicle: clear, elastic layer of protein surrounds the cell membrane
Oral groove: funnel-like depression lined with cilia. Beating cilia create water currents that sweep food down groove to mouth pore and gullet where food vacuole forms.

34. Anal pore: where waste is expelled
Multinucleated: have at least one macronucleus and one micronucleus.
Macronucleus contains multiple copies of DNA and is responsible for metabolic and developmental functions necessary for asexual reproduction.
Micronucleus: participates in exchange of genetic info during conjugation.

36. Reproduction in Ciliophora
Asexual reproduction by binary fission
Only the micronucleus divides by mitosis.
Macronucleus which has up to 500x more DNA than the micronucleus, simply elongates and splits in half. One goes into each new cell

37. Sexual reproduction by Conjugation
Two organisms of opposite mating strains line up and join together.
Macronucleus disintegrates
Each diploid micronucleus undergoes meiosis, producing 4 haploid micronuclei. All but one disintegrates.
Remaining micronuclei divides by mitosis producing 2 identical haploid micronuclei.
Two paramecium exchange 1 micronuclei

38. The 2 micronuclei in each fuse to form one diploid micronucleus in each paramecium.
Paramecium separate.
Macronucleus forms in each from products of mitotic divisions of the micronucleus.
Although genetic material was exchanged no new cells are produced.
Following conjugation, each paramecium divides, producing a total of 4 genetically identical paramecia which are genetically different from either of the original paramecia.

41. Phylum Zoomastigina 2500 species
Trichomonas
2500 species
Characterized by presence of one or more flagella: long hair-like structures that are made up of microtubules and are used for movement.
rapid whipping motion pushes or pulls protozoan through water

42. Phylum Zoomastigina
Many are free-living in ponds or lakes and feed on small organisms.

43. Phylum Zoomastigina Example: Giardia lamblia (giardiasis)
Severe diarrhea, intestinal cramps.
Several kinds of animal carry parasite and contaminate water with their feces.
Trichonympha live in the gut of termites and help digest cellulose.

44. Human Disease of Zoomastigina
Genus Trypanosoma:
live in blood of fish, amphibians, reptiles, birds, and mammals.
Carried from host to host by bloodsucking insects
African trypanosomiasis: sleeping sickness. Transmitted by tsetse fly. Causes fever, lethargy, mental disorientation, coma
Trypanosoma

45. Trypanosoma cruzi: Chagas’ disease. Transmitted by “kissing bug”
Trypanosoma cruzi: Chagas’ disease. Transmitted by “kissing bug”. Fever and severe heart damage.

46. Leishmania donovani: Transmitted by sand fleas. Causes leishmaniasis.
Blood disease afflicts millions of people in Africa, Asia and Latin America.
Disfiguring skin sores, can be fatal.

47. Phylum Sporozoa 6,000 species No means of locomotion in adults
Plasmodium
6,000 species
No means of locomotion in adults

48. Phylum Sporozoa Most species are parasitic
Have complex life cycles in which they develop a spore
Infective form protected by a resistant coat
Carried in the blood and other tissues of their hosts where they absorb nutrients and destroy host tissues.

49. Example: Toxoplasma gondii:
Found in birds, rodents, and domestic cats.
Causes toxoplasmosis.
Few to no symptoms in healthy adults but can cause damage to developing fetus or newborn.

51. Example: Plasmodium Causes malaria.
Characterized by severe chills, fever, sweating, fatigue, and great thirst.
Victims die of anemia, kidney failure or brain damage.
Four species infect humans. All have life cycles that involve the female Anopheles mosquito.

54. Treating Malaria
An effective way to reduce human deaths from malaria is to control mosquito population and interrupt the parasite’s life cycle.
Cured with drug derived from Cinchona tree, native to Americas. Quinine used for over 500 years.
Sporozoan’s resistance to antimalarial drugs is a significant worldwide problem. Possible vaccination developed in the future.