Biology Chapter: Fungi and Algae Quiz

Lecture PowerPoint on Foundations in Microbiology

• Title: Foundations in Microbiology, Sixth Edition
• Author: Kathleen Park Talaro
• Chapter: 5, Eucaryotic Cells and Microorganisms

History of Eucaryotes

• Appeared approximately 2 billion years ago.
• Evolved from procaryotic organisms through symbiosis.
• Organelles originated from procaryotic cells, trapped within eucaryotic cells.

Structure Flowchart

• External Boundary of a Eucaryotic Cell:
  • Appendages (flagella, cilia), glycocalyx, capsules and slimes
  • Cell wall
  • Cytoplasmic membrane
• Internal Structures of a Eucaryotic Cell:
  • Cytoplasmic matrix
  • Nucleus (nuclear envelope, nucleolus, chromosomes)
  • Organelles (endoplasmic reticulum, Golgi complex, ribosomes, mitochondria, chloroplasts, lysosomes)
  • Cytoskeleton (microtubules, microfilaments)

Internal Structures Details

• Endoplasmic Reticulum:
  • Two types: Rough (RER) and Smooth (SER)
  • RER: originates from the outer nuclear membrane, studded with ribosomes, synthesizes and packages proteins, initial step in secretory pathway
  • SER: closed tubular network, lacks ribosomes, involved in nutrient processing, lipid synthesis and storage
• Golgi Apparatus:
  • Flattened sacs (cisternae), closely associated with ER
  • Modifies and packages proteins targeted for secretion or to other organelles
• Lysosomes:
  • Vesicles containing enzymes originating from the Golgi apparatus
  • Involved in intracellular digestion of food particles and defense against invading microbes
• Mitochondria:
  • Consists of outer and inner membranes (cristae)
  • Cristae hold enzymes and electron carriers for aerobic respiration
  • Divide independently of the host cell
  • Contain DNA and procaryotic ribosomes
  • Function in energy production
• Chloroplasts:
  • Found in algae and plant cells
  • Outer membrane covers inner membrane folded into sacs (thylakoids, stacked into grana)
  • Larger than mitochondria
  • Contain photosynthetic pigments (chlorophyll)
  • Convert sunlight energy into chemical energy via photosynthesis
  • Primary producers of nutrients
• Ribosomes:
  • Composed of rRNA and proteins
  • 40S and 60S subunits form 80S ribosomes (larger than procaryotic ribosomes)
  • Function in protein synthesis
• Cytoskeleton:
  • Flexible protein framework (microfilaments, microtubules)
  • Forms throughout the cytoplasm
  • Involved in cytoplasm movement, amoeboid movement, transport, and structural support

External Structures

• Glycocalyx:
  • Outermost boundary contacting the environment
  • Polysaccharides
  • Functions in adherence, protection and signal reception
  • Beneath the glycocalyx, fungi and most algae have rigid cell walls. Others (protozoa, some algae, animal cells) have only a membrane.
• Cell Wall:
  • Rigid structure providing support and shape.
  • Fungi: thick inner layer of polysaccharides (like chitin or cellulose), and a thin layer of mixed glycans.
  • Algae: varies in chemical composition (cellulose, pectin, mannans, silicon dioxide, calcium carbonate).
• Cytoplasmic (cell) Membrane:
  • Typical bilayer of phospholipids and proteins
  • Sterols provide stability
  • Serves as a selectively permeable barrier in transport
  • Eucaryotic cells also contain membrane-bound organelles accounting for 60-80% of their volume.
• Locomotor Appendages (flagella, cilia):
  • Movement
  • Flagella: long, sheathed cylinder containing microtubules in a 9+2 arrangement. 10x thicker than prokaryotic flagella.
  • Cilia: similar to flagella, much shorter and more numerous, found only in some protozoa and animal cells, function in motility, feeding and filtering.

Survey of Eucaryotic Microbes

• Fungi
• Algae
• Protozoa
• Parasitic worms

Kingdom Fungi

• 100,000 species
• Divided into two groups: macroscopic (mushrooms, etc) and microscopic (molds, yeasts)
• Majority are unicellular or colonial. Some have cellular specialization.

Microscopic Fungi

• Yeast (Round ovoid, asexual reproduction)
• Hyphae (long filamentous, fungi molds)
• Some are dimorphic (exist as yeast or hyphae)

Fungal Organization

• Grow in loose associations or colonies
• Yeast: soft, uniform appearance
• Filamentous Fungi: mycelium (mass of hyphae) – cottony, hairy or velvety texture
• Hyphae: divided by cross walls (septate) or not (nonseptate); vegetative or reproductive, the reproductive function in producing spores
• Vegetative hyphae: digest and absorb nutrients
• Reproductive hyphae: produce spores

Fungal Reproduction

• Primarily through spores on reproductive hyphae
• Asexual reproduction: spores via budding or mitosis, conidia, sporangiospores
• Sexual reproduction: through fusion of strains, formed sexually structure, Spores and spore-forming structures are a basis for classification

Fungal Classification

• Subkingdom Amastigomycota (terrestrial, medical importance)
  • Zygomycota
  • Ascomycota
  • Basidiomycota
  • Deuteromycota

Fungal Identification

• Isolation on specific media for macroscopic and microscopic observations
• Asexual spore-forming structures and spores
• Hyphal type
• Colony texture and pigmentation
• Physiological characteristics
• Genetic makeup

Roles of Fungi

• Adverse: mycoses, allergies, toxin production, crops/food storage destruction
• Beneficial: decomposers, sources of antibiotics, alcohol, organic acids, vitamins, used in foods/genetic studies

Kingdom Protista

• Algae
• Protozoa

Algae

• Photosynthetic organisms
• Kelps, seaweeds, euglenids, green algae, diatoms, dinoflagellates, brown algae, red seaweeds
• Unicellular, colonial, filamentous or multicellular macroscopic forms
• Contain chloroplasts and chlorophyll and other pigments
• Cell wall, may or may not have flagella
• Mostly free-living in fresh and marine waters (plankton).
• Produce a large proportion of atmospheric oxygen
• Dinoflagellates can cause red tides and toxins causing food poisoning with neurological symptoms
• Used for cosmetics, food and medical products.

Protozoa

• 65,000 species
• Vary in shape
• Primarily unicellular, rarely colonial
• Most harmless, free-living in moist habitats
• Some are animal parasites, transmitted by insect vectors
• Heterotrophic
• Feed by engulfing other microbes and organic matter
• Most have locomotor structures (flagella, cilia, pseudopods)
• Exist as trophozoite (motile form) or cyst (dormant resting form)
• Asexual reproduction (mitosis, multiple fission) and sexual reproduction (conjugation)

Protozoan Identification and Classification

• Difficult due to diversity
• Simple grouping based on motility, reproduction, life cycle
  • Mastigophora (flagella)
  • Sarcodina (amebas)
  • Ciliophora (cilia)
  • Apicomplexa (no motility except male gametes, all parasitic, complex life cycles)

Important Protozoan Pathogens

• Pathogenic flagellates: Trypanosoma brucei (African sleeping sickness), Trypanosoma cruzi (Chagas' disease)
• Infective amebas: Entamoeba histolytica (amebic dysentery)

Parasitic Helminths

• Multicellular animals
• Organs for reproduction, digestion, movement, protection
• Parasitize host tissues, have mouthparts for attachment or digestion
• Most have well-developed sex organs
• Fertilized eggs go through larval stage in or out of host body

Major Groups of Parasitic Helminths

• Flatworms (flat, blind digestive tract, simple excretory/nervous systems)
  • Trematodes (flukes)
  • Cestodes (tapeworms)
• Roundworms (nematodes) (complete digestive tract, protective cuticle, spines/hooks, excretory/nervous systems poorly developed)

Helminths

• 50 species parasitize humans
• Through ingestion of larvae/eggs in food, soil or water; some carried by insect vectors
• Affect billions worldwide

Helminth Classification and Identification

• Classify according to shape, size, organ development, hooks/suckers, other structures, mode of reproduction, hosts and appearance of eggs/larvae
• Identify by microscopic detection of adult worm, larvae or eggs

Distribution and Importance of Parasitic Worms

• Approximately 50 species parasitize humans.
• Distributed worldwide; some restricted to specific regions with higher incidence in the tropics.

Test your knowledge on the roles and characteristics of fungi and algae in ecosystems. This quiz covers topics such as nutrition, reproductive structures, and the impact of these organisms on their habitats. Gain a deeper understanding of the vital functions these life forms serve in nature.