BIO 151: Eukaryotic Protists - Fungi and Algae

Eukaryotes

• Eukaryotes have complex cells with membrane-bound nuclei containing genetic material.
• The term "eukaryote" translates to "true nucleus," originating from Greek.
• Eukaryotes include multicellular organisms (animals, plants, fungi, algae) and unicellular organisms (yeasts).
• Eukaryotic cells are generally larger than prokaryotic cells, with distinct internal organelles.
• A cytoskeleton made of microtubules, microfilaments, and intermediate filaments supports cell structure.

Organelles

• Nucleus: Most prominent organelle, contains DNA in the form of linear chromosomes, separated during cell division by microtubular spindles.
• Mitochondria: Double-membraned organelles where aerobic respiration occurs; contain their own DNA.
• Lysosomes: Organelles that house enzymes for food breakdown.
• Peroxisomes: Contain catalase for converting hydrogen peroxide into water and oxygen.
• Endoplasmic Reticulum (ER) & Ribosomes: Involved in protein production; the Golgi apparatus processes these proteins.

Fungi

• Zygomycetes (e.g., Mucor, Rhizopus):

  • Aseptate (coenocytic) hyphae, zygospores as sexual spores, resistant to adverse conditions, form mycorrhizal associations with plants.

• Basidiomycetes (Club fungi, e.g., Agaricus, Amanita):

  • Septate hyphae, basidiospores produced on basidia; includes mushrooms and plant pathogens like rusts and smuts.

• Oomycetes (Water Moulds, e.g., Albuginales):

  • Aseptate hyphae; thick-walled oospores as sexual spores; cell walls made of cellulose, some aquatic.

• Deuteromycetes (Fungi Imperfecti):

  • Septate hyphae; only known to reproduce asexually; typical members include Penicillium, Aspergillus, Candida.

Algae

• Algae are photosynthetic eukaryotes, primarily aquatic, with some terrestrial species.

• Photosynthetic pigments include chlorophylls a and c, along with xanthophylls.

• Carbohydrates are stored as starch; cellulose constitutes their cell walls.

• Phylum Phaeophyta (Brown Algae):

  • Multicellular organisms, pigments include chlorophylls a and c, fucoxanthin; store carbohydrates as laminarin.

• Phylum Rhodophyta (Red Algae):

  • Mostly multicellular, pigments include chlorophylls a and d, phycocyanin, and phycoerythrin; store carbohydrates as starch.

Protozoa

• Protozoans are diverse, unicellular eukaryotes that are non-photosynthetic and generally heterotrophic.

• Lack cellulose cell walls, commonly found in aquatic environments; many are parasitic, causing diseases in humans.

• Protozoans reproduce mainly through phagocytosis, engulfing food particles, and some possess specialized structures like gullets.

• Sarcodina (Amoebas):

  • Characterized by pseudopodia; reproduce by binary fission; some are parasites (e.g., Entamoeba histolytica).

• Mastigophora (Flagellates):

  • Feature long flagella for movement; includes pathogenic species such as Trypanosoma gambiense (African sleeping sickness).

• Ciliophora (Ciliates):

  • Possess cilia for movement and feeding; exhibit two types of nuclei; Paramecium is a well-known example, while Balantidium coli causes dysentery.

• Apicomplexa (Sporozoans):

  • Obligate parasites, typically non-motile; Plasmodium causes malaria, transmitted by Anopheles mosquitoes; Toxoplasma leads to toxoplasmosis.

This quiz covers the fundamental aspects of eukaryotic organisms, with a focus on protists like fungi and algae. Understand the classification and characteristics that define these complex cells, as discussed in BIO 151. Test your knowledge and explore the diversity within the eukaryotes.