1. Characterizing and Classifying Eukaryotes
Chapter 12
Characterizing and Classifying Eukaryotes

2. Eukaryotes Four major groups
Protozoa
Fungi
Algae
Water molds and slime molds
Include both human pathogens and organisms vital for human life

3. Reproduction in Eukaryotes
More complicated than that in prokaryotes
Eukaryotic DNA packaged as chromosomes in the nucleus
Have variety of methods of asexual reproduction (budding, fragmentation, spore formation, and schizogony)
Many reproduce sexually by forming gametes and zygotes
Algae, fungi, and some protozoa reproduce sexually and asexually

4. Classification of Eukaryotic Organisms
Figure 12.4

5. Protozoa Diverse group defined by three characteristics
Eukaryotic
Unicellular
Lack a cell wall
With exception of the group apicomplexans, they are motile by means of cilia, flagella, and/or pseudopodia

6. Distribution of Protozoa
Require moist environments
Most live worldwide in ponds, streams, lakes, and oceans; critical members of plankton
Others live in moist soil, beach sand, and decaying organic matter
Very few are pathogens

7. Morphology of Protozoa
Characterized by great morphologic diversity
Some have two nuclei
Macronucleus contains many copies of genome – controls metabolism, growth, and sexual reproduction
Micronucleus – involved in genetic recombination, sexual reproduction, and regeneration of macronuclei
Variety in number and kinds of mitochondria
All produce trophozoites; some produce cysts

8. Life Cycle of Parasitic Protozoans
consists of two stages: trophozoite (motile feeding stage) and cyst (resting stage)
under certain adverse conditions, some trophozoites produce a protective cyst.
this cyst enables parasitic species to survive outside of a host

9. Nutrition of Protozoa Most are chemoheterotrophic
Obtain nutrients by phagocytizing bacteria, decaying organic matter, other protozoa, or the tissues of host
Few absorb nutrients from surrounding water
Dinoflagellates and euglenoids are photoautrophic

10. Reproduction in Protozoa
Most reproduce asexually only (binary fission or schizogony)
Few also have sexual reproduction
Some become gametocytes that fuse with one another to form diploid zygote
Some utilize a process called conjugation

11. Characteristics of Protozoa
Table 12.2

12. Classification
Protozoans are often classified into four groups based on mode of locomotion:
Sarcodina (pseudopodia)
Mastigophora (flagella)
Ciliophora (cilia)
Sporozoa (non-motile)

13. Sarcodina
Move and feed by pseudopodia using amoeboid motion

14. Entamoeba histolytica
lobe-shaped pseudopodia
no shell
some are disease causing
Ex. Entamoeba histolytica
live inside animals
cause of amebic dysentary through the lysis of human intestinal cells
infection occurs through ingestion of drinking water with contaminated feces, hands, food, or oral-anal intercourse
Annual mortality of 100,000

15. Classification
Protozoans are often classified into four groups based on mode of locomotion:
Sarcodina (pseudopodia)
Mastigophora (flagella)
Ciliophora (cilia)
Sporozoa (non-motile)

16. Mastigophora
move by flagella

17. Giardia intestinalis Diarrhea-causing pathogen (giardiasis)
Spread in the cyst form in fecal contaminated water, food, soil.

18. Trichomonas vaginalis
Most common protozoan disease (trichomoniasis)
Transmitted via sex
Occurs most frequently in people with a preexisting STD

19. Trypanosoma Hemoflaggellates: blood parasite
Ex. Trypanosome: causative agent of African Sleeping sickness
Transmitted by the tse-tse fly

20. Life cycle of Trypanosoma brucei, causative agent of African sleeping sickness

21. Dinoflagellates Unicellular Photoautotrophs also considered protozoans
Freshwater and marine plankton
Two flagella of unequal length

22. Red Tide Some dinoflagellates produce red pigment
An abundance of these organisms produces “red tide”
Red tide blooms produce neurotoxins that are toxic to marine life

23. Red Tide

24. Pfiesteria Dinoflagellate
Poisons people who handle infected fish or inhalation of microbes

25. BAD DINOFLAGELLATES: PARALYTIC SHELLFISH POISONING
Red Tide strikes again
DEP shuts down shellfish harvesting
in waters of Bay and Gulf counties
News Herald Staff Report
State environmental officials closed Bay County and Gulf County waters to shellfish harvesting Thursday after detecting unacceptable levels of red tide.
Water samples taken from Mexico Beach showed medium levels of red tide - about 933,000 cells per liter. DEP shuts down shellfish harvesting when levels reach 5,000 cells per liter.

26. BAD DINOFLAGELLATES: PARALYTIC SHELLFISH POISONING

27. Classification
Protozoans are often classified into four groups based on mode of locomotion:
Sarcodina (pseudopodia)
Mastigophora (flagella)
Ciliophora (cilia)
Sporozoa (non-motile)

28. Balantidium coli
human parasite that causes a rare type of severe dysentery (Balantidiasis)
ingested as cysts, they enter the intestine and trophozoites are released
the trophozoites destroy host cells and feeds on the host cell fragments

29. Classification
Protozoans are often classified into four groups based on mode of locomotion:
Sarcodina (pseudopodia)
Mastigophora (flagella)
Ciliophora (cilia)
Sporozoa (non-motile)

30. Sporozoans (Apicomplexans)
Animal pathogens
Adults are non-motile
Ex. Plasmodium (Genus) – causative agent of malaria

31. Eukaryotes Four major groups
Protozoa
Fungi
Algae
Water molds and slime molds
Include both human pathogens and organisms vital for human life

32. Fungi Chemoheterotrophic Have cell walls typically composed of chitin
Decompose dead organisms and recycle their nutrients
Have cell walls typically composed of chitin
Related to animals
Important research tools

33. Significance of Fungi
Form beneficial associations with roots of vascular plants that help plant absorb water and minerals
Used for food and in manufacturing of foods and beverages
Produce antibiotics
30% cause diseases of plants, animals, and humans
Can spoil fruit, pickles, jams, and jellies

34. Nutrition of Fungi Acquire nutrients by absorption
Most are aerobic; some are anaerobic; many yeasts are facultative anaerobes

35. Fungal Morphology
the body of fungi is termed thallus (non-reproductive)
The thalli of yeast are small, globular and are single celled
The thalli of mold are composed of long, branched tubular filaments called hyphae.

36. Fungal Morphology
Within multi-ceullar hyphae of molds, the can either be separated (septae) or continuous (aseptate)

37. Fungal Morphology Some members of fungi are dimorphic.
They take either a globular form or filamentous form depending on environmental conditions.

38. Reproduction of Fungi All have some means of asexual reproduction
Yeasts bud in manner similar to prokaryotic budding
Filamentous fungi produce lightweight spores that differ in mode of development
Most also reproduce sexually

39. Budding and Asexual Spore Formation

40. Asexual Spores of Molds
Some asexual spores are enclosed in sacs called sporangium at the end of the hyphae.
Figure 12.19a

41. Asexual Spores of Molds
Some asexual spores are located in the middle of the hyphae and enclosed in a thick wall (chlamydiospores).

42. Asexual Spores of Molds
Some asexual spores called conida are not enclosed in sacs at the end of the hyphae.

43. Asexual Spores of Molds
The type of asexual spore produced by a mold is often used clinically to identify the identity of the mold pathogen.

44. Sexual Spores Formation

45. Eukaryotes Four major groups
Protozoa
Fungi
Algae
Water molds and slime molds
Include both human pathogens and organisms vital for human life

46. Algae
Simple, eukaryotic, phototrophic organisms that carry out oxygenic photosynthesis.
Reproduce asexually and sexually.
Differ widely in distribution, morphology, reproduction, and biochemical traits

47. Distribution and Morphology of Algae
Most are aquatic, living in the photic zone of fresh, brackish, and salt water
Unicellular, colonial, or have simple multicellular bodies (thalli)

48. Classification of Various Algae
Table 12.4

49. Red Algae
Figure 12.29

50. Diatom Single-celled Silicon in cell walls composed of two halves
Major component of phytoplankton
Major source of world’s O2
Figure 12.32

51. Brown Algae
Figure 12.31

52. Parasitic Helminths and Vectors
Parasitic worms have microscopic infective and diagnostic stages – usually eggs or larvae
Vectors are animals such as ticks, lice, and mosquitoes that carry and transmit microscopic pathogens

53. The Helminths Helminths (parasitic worms) Multicellular eukaryotes
Consumers
Common intestinal parasites
Kingdom: Animalia
Phylum: flatworms
Class: flukes
Class: tapeworms
Phylum: roundworms
Table 12.1

54. Flatworms Structurally simple Most are parasitic Hermaphrodites
Two classes:
Fluke
tapeworms
Liver Fluke

55. Flatworm: Flukes flat, leaf shaped bodies
contain oral and ventral suckers that allow for attachment to the host
Clonorchis
(Chinese Liver Fluke)

56. Flukes Complex life cycle Multiple hosts Multiple Stages
Intermediate host
Definitive host
Multiple Stages

57. Flatworm: Tapeworms flat, segmented, intestinal parasites Scolex
Small attachment organ
Contains suckers and hooks
Proglottid
Irradiate from the neck
Grow continuously
Contains reproductive organ (monoecious)

58. Tapeworms – life cycle

59. Roundworms Long, cylindrical; tapered at each end
Complete digestive tracts
Dioecious (females are larger)

60. Life Cycle of Trichinella spiralis

61. Arthropods as Vectors Kingdom: Animalia Phylum: Arthropoda
Class: Insecta (6 legs)
Lice, fleas, mosquitoes
Class: Arachnida (8 legs)
Mites and ticks
May transmit diseases (vectors)
Figure 12.31, 32