Characterizing and Classifying Eukaryotes Chapter 12 Characterizing and Classifying Eukaryotes

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

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

Classification of Eukaryotic Organisms Figure 12.4

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

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

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

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

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

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

Characteristics of Protozoa Table 12.2

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

Sarcodina Move and feed by pseudopodia using amoeboid motion

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

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

Mastigophora move by flagella

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

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

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

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

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

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

Red Tide

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

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.

BAD DINOFLAGELLATES: PARALYTIC SHELLFISH POISONING

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

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

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

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

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

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

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

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

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.

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

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

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

Budding and Asexual Spore Formation

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

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

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

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.

Sexual Spores Formation

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

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

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)

Classification of Various Algae Table 12.4

Red Algae Figure 12.29

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

Brown Algae Figure 12.31

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

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

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

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

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

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)

Tapeworms – life cycle

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

Life Cycle of Trichinella spiralis

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