Eukaryotes

Eukaryotes
Modes of Nutrition

• Nutrition refers to the means by which an organism obtains matter and energy, typically for growth and repair.

Sources of matter include two types:

• Organic: molecule containing both carbon and hydrogen
• Example: glucose
• Inorganic: molecule not containing both carbon and hydrogen
• Example: carbon dioxide

Energy may also be obtained from light or chemical sources

Terminology

• Autotrophism: do not require organic food. The organism is able to live on just inorganic molecules along with some sort of energy source
• Photosynthetic autotrophism: energy source is light, carbon dioxide is their chief source of carbon
•  Example: green plants, algae, photosynthetic bacteria
• Chemoautotrophism: energy source is from reduced inorganic compounds, carbon dioxide is the chief source of carbon
• Example: some bacteria

• Heterotrophism: need organic energy and carbon source
• Chemoheterotrophism: this group includes nearly all of the medically important microbes, all fungi, protozoa and animals
• Parasitism: this group derive nutrients from a living host organism
• Example: viruses
• Saprophytism (ex: plants) or saprotrophism (ex: animals): live on dead organic matter (decay)

Fungi

Fungi

• General information
• Eukarya Domain, Fungi Kingdom
• Important as food, industrial processes, pathogens and decay organisms
• Mycology: study of fungi
• Mycosis: any disease caused by a fungus
• The human diseases produced by fungi tend to be chronic and slow to develop

Characteristics of fungi

Yeasts are single celled fungus
Molds are multicellular fungi

Lichens

• Lichens consist of two eukaryote organisms living in close association: a fungus and an alga
• The alga will photosynthesize, providing carbohydrates for the lichen, while the fungus provides a holdfast

Algae

• Eukaryote
• Have cell wall
• Single or multicellular
• Photosynthetic autotrophic nutrition-no parasites
• Vary in size
• No specialized tissues such as roots, stem or leaves
• Live only water or damp places

Diatoms

• Unicellular or filamentous algae
• With complex cell wall consisting of pectin and a layer of silica
• Store energy in the form of oil via photosynthesis
• Produce domoic acid, a neurotoxin that can be concentrated in the mussels

Dinoflagellates

• Unicellular microscopic algae
• Can be the cause of red tides
• Large concentrations gives the ocean a deep red color
• Produces neurotoxin

Protozoa

• Unicellular
• Eukaryotic cells; eukaryote
• Chemoheterotrophic: parasitic or non-parasitic
• No cell wall
• Usually motile
• Microscopic size
• Out of nearly 20,000 species, only few cause disease
• One example is the Entamoeba histolytica

Terminology relating to Protozoa

• Trophozite: the feeding and growing stage of protozoa
• Cyst: the dormant and surviving form
• Under certain adverse conditions, some protozoa produce this protective capsule

Protozoa

• Protozoa can be divided into four groups:

• Amoebas
• Flagellate
• Ciliate
• Apicomplexa

• Amoebas:
• Moves by pseudopodia (false feet) – cytoplasmic streaming
• helps cytoplasm move from one place to another
• Entamoeba histolytica: one of few pathogenic amoebas
• Causes amoebic dysentery
• Found in the human intestine
• Produces protective cysts which pass out of the intestines of the infected host and are ingested by the next host (fecal-oral route)

• Flagellate Protozoa
• Move by flagella (long whip-like structures for motility)

• Most have two or more flagella
• Some also have an undulating membrane: membrane bordered by a flagellum

• Many pathogens (some examples given)

• Trichomonas vaginalis
• Trichomoniasis: infection in the vagina and the male urinary tract
• It does not produce a cysts stage
• Only known protozoa without a cyst
• Is usually transmitted by sexual contact
• Has one nuclei

• Trypanosoma (brucei) gambiens
• Causes African sleeping sickness affecting central nervous system
• Infection in blood and lymph and goes to the CNS
• Transmitted by the bite of an infected Tsetse
• pathogen is in the saliva of Tsetse

• Trypanosoma cruzi
• Causes Chagas’ disease (American trypanosomiasis)
• Affects cardiovascular system
• Pathogen can be found in the heart muscle
• Vector: triatoma ssp. (kissing bug)

• Ciliate protozoa
• Move by cilia (short, hair-like projections for motility)
• Only one known pathogen so far:
• Balantidium coli
• Causes balantidiasis
• Intestinal infection

• Apicomplexa protozoa
• Intracellular protozoa with complex life cycles
• Intracellular parasites
• Nonmotile during their mature forms
• Several pathogens (one example)
• Plasmodium spp.: cause malaria (pathogens grow in the host’s red blood cells)
• Plasmodium vivax: the most common
• Vectors: Mosquitoes
• Plasmodium spp.
• Pathogens reproduce asexually by schizogony in human liver cells and red blood cells, but also reproduce sexually by gametes in the mosquito
• Schizogony is a form of multiple fission

Helminthes—Parasitic Worms

• Multicellular eukaryotic animals

Anthropods

• Animal Kingdom
• Eukaryotes
• Jointed appendages
• Exoskeleton of chitin
• Insects, crustaceans, ticks and spiders are examples
• Arthropods are important vectors of human diseases
• Arachnida:
• Lyme disease, Rocky Mountain Spotted Fever
• Insecta:
• Mosquito
• Dengue fever, yellow fever, malaria
• Flies
• African trypanosomiasis
• Body louse
• Epidemic Typhus
• Flea
• Plague

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