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