Algae and Microalgae Quiz

Algae and Microalgae: Biology, Applications, and Significance

• Algae are categorized by their energy and carbon sources:
  • Autotrophs: Light energy, inorganic carbon
  • Heterotrophs: Organic energy, organic carbon
  • Mixotrophs: Light and organic energy, inorganic and organic carbon
  • Photoheterotrophs: Light energy, organic carbon
• Algae reproduce asexually (spores) and sexually (gametes). Some lack sexual reproduction. Cyanobacteria reproduce asexually, but exchange genetic material.
• Trichomes: Hair-like structures, often chains of cells, in cyanobacteria.
• Rhizoid: Root-like structures in some algae for anchorage.
• Frustule: The siliceous outer wall of diatoms.
• Cytopharynx: Specialized feeding structure in some protozoans.
• Theory of endosymbiosis: Hypothesis explaining the origin of organelles like mitochondria and chloroplasts.
• Sulcus: Groove in dinoflagellates housing flagella.
• Cingulum: Groove in the surface of dinoflagellates or diatoms, often housing flagella.
• Coccosphere: Spherical structure formed by the arrangement of coccoliths around the cell.
• Primary Endosymbiosis: The initial engulfment of a prokaryote by a eukaryote, leading to organelles like chloroplasts.
• Coccolith: Calcium carbonate plates produced by coccolithophores.
• Cauloid: Stem-like structure in algae.
• Hypotheca: Bottom half of a diatom's siliceous cell wall or frustule.
• Heterocyst: Specialized nitrogen-fixing cells in some cyanobacteria.
• Pigments: Molecules like chlorophyll, carotenoids, and phycobilins that capture light for photosynthesis.
• Centroplasm: Non-pigmented region in algal cells where the nucleus is located.
• Stigma: A light-sensitive structure, often associated with phototaxis.
• Mastigonemes: Hair-like structures on flagella, increasing propulsion efficiency.
• Ejectisomes: Organelles in some algae used for defense or movement.
• Periplast: A structure covering the plasma membrane in some algae.
• Cortex: Outer layer of certain algal thalli.
• Chromatoplasm: Pigmented part od the cytoplasm in photosynthetic organisms.
• Cyanella: Endosymbiotic cyanobacteria or photosynthetic components of Glaucophytes.
• Haptonema: Unique organelle in haptophytes involved in feeding or sensory functions.
• Epitheca: The upper valve of a diatom frustule.
• Medulla: The innermost part of a multilayered algal thallus.
• Nucleomorph: Vestigial nucleus found in some algal endosymbionts.
• Phycobilisome: Protein complexes involved in light harvesting in cyanobacteria and red algae.
• Phycocolloids: Gel-forming substances derived from algae (agar carrageenan).
• Phylloid: Leaf-like structures in algae.
• Raphe: Groove in some diatom species aiding in movement.

Algae Reproduction and Life Cycles

• Algae exhibit complex life cycles with alternating haploid (gametophyte) and diploid (sporophyte) phases (alternation of generations).
• Sporophytes produce spores in sporangia.
• Gametophytes produce gametes in gametangia (antheridia and oogonia).
• Gametangia and sporangia typically lack protective coverings.

Morphology and Habitat

• Diatoms: Centric diatoms show radial symmetry; pennate diatoms have non-radial symmetry.
• Cosmopolitan distribution: Primarily aquatic, but some species inhabit subaerial habitats (lichens) or extreme environments like hot springs (up to 75°C) or arctic/antarctic regions.
• Marine environments: Phytoplankton (dinoflagellates, diatoms, coccolithophorids, cyanobacteria) and phytobenthos (green, brown, and red algae) populate various marine zones, from the splash zone to depths with 0.0005% surface light. Also freshwater phytoplankton and periphyton.
• Coccosphere Functions: protection against microzooplankton predation, flotation buoyancy, light regulation, biochemistry.
• Dinokont form: with a transversal and longitudinal flagellum.
• Desmokont form: flagella arise from a pore in the apical part.

Algae Pigments: Health benefits and applications

• Fucoxanthin: A carotenoid with notable health benefits including glycemic and inflammatory regulation and inhibition of cancer cell invasion.
• Microalgae pigments: Possess cytostatic and pro-apoptotic activities against cancer, inhibiting tumor formation, growth, and spread. They can sensitize tumor cells to cytotoxic drugs. Exhibits potential as photosensitisers in PDT (photodynamic therapy).

Primary and Secondary Metabolites

• Primary metabolites: Crucial for cellular function: membranes, walls, exopolysaccharides, and energy storage compounds (polysaccharides, lipids).
• Secondary metabolites: Not directly involved in essential processes, but are involved in defense, competition and communication, including terpenes, pigments, toxins, polyamines, alkaloids, sterols, and heterocycles.

ω-3 PUFAs and Microalgae

• ω-3 PUFAs: Have health benefits including reducing pregnancy complications, preventing atherosclerosis/myocardial infarction, increasing response to viral/bacterial threats.
• Mechanism: ω-3 PUFAs affect cytoplasmic membrane fluidity and are linked to better chemotherapy absorption. Relevant for pregnancy, fetal development, cardio protection, immunity, and inflammation.

Microalgae Phototherapy for Acne

• Antibacterial phototherapy: Extracts from microalgae offer natural, eco-friendly photoactive agents to improve mild-to-moderate acne.
• Targets S. aureus, S. epidermidis, and C. acnes.

Microwave-Assisted Extraction (MAE) of Pigments

• Extraction method: MAE is the only method allowing the total extraction of microalgae pigments under controlled temperature conditions.
• Mechanism: Microwaves vibrate water/polar molecules, leading to increased intracellular temperatures, resulting in water evaporation and cell disruption.

Functional & Ecological Significance of Microalgae Pigments

• Photosynthesis/Protection: Diverse pigments optimize photosynthesis by absorbing various light wavelengths, protecting against photodamage, and enhancing energy conversion.
• Ecological importance: Diverse pigments reduce competition and support biodiversity. Also contribute to global carbon fixation and oxygen production.

Microalgae as Cell Factories

• Therapeutic protein synthesis: Microalgae efficiently synthesize therapeutic proteins (hormones, cytokines, antibodies, vaccines).
• Advantages: Easily grown, no pathogenic viruses, prions, or endotoxins.

Metabolism

• Many algae are nutritionally versatile.
• Mixotrophs: Algae can exhibit autotrophic and heterotrophic behaviors, adapting to environmental conditions based on organic compounds and light.

Algae Reproduction

• Reproduction involves asexual (spores) and sexual (gametes) methods, and some groups lack sexual reproduction.

Levels of Organization (Algae)

• Protophytes: Unicellular or inconsistent aggregates lacking functional specialization.
• Coccoid: Unicellular. Examples: Chlorella, Pinnularia, Micrasterias
• Monadoid: Unicellular, motile. Examples: Phacus, Ceratium, Euglena, Chlamydomonas.
• Colonial
  • Palmelloid: Colonies lacking defined form, cells grouped in a gelatinous matrix. Examples: Sphaerocystis, Gloeocystis
  • Cenobium: Colonies with defined form, specific cell numbers depending on the genus. Examples: Synura, Gonium, Pediastrum
• Thallophytes: Mulicellular, with work division, and intercellular cohesion. Aquatic, lack water regulation. Thallus (algal body). Examples: various branched/unbranched filamentous types, pseudoparenchymatous, parenchymatous, and siphonal thalli.

Additional Information

• Classification and Nomenclature: Algae are classified into various kingdoms (Plantae, Chromista, Bacteria, Protozoa) and phyla, reflecting their diversity.
• Diatom Cell Covering: Diatoms have elaborate cell covers (frustules) with ornate designs and pores, important for taxonomy. Mucilage is secreted through the pores. Each frustule has two valves (epitheca and hypotheca) fitting together.
• Primary and Secondary Metabolites Differences: Primary metabolites are essential for cellular functions and organization (e.g., membranes, cell walls, energy stores). Secondary metabolites are not essential, but often involved in defence, competition, and communication.
• Health Benefits of Microalgae Pigments: Microalgae pigments can have various health benefits, e.g., anti-cancer (fucoxanthin inhibits cancer cell invasivity, metastasis and angiogenesis etc.) and phototherapeutic (treat mild to moderate acne) properties due to their cytostatic, pro-apoptotic activities.
• ω-3 PUFAs: These fatty acids are beneficial for human health by reducing pregnancy complications, preventing atherosclerosis and myocardial infarction. They aid in response to viral/bacterial threats, have a cardioprotective effect, and help with immunity and inflammation while enhancing chemotherapy absorption.
• Microwave-assisted Extraction (MAE): The only known method to fully extract microalgae pigments under controlled temperature, by vibrating polar molecules, causing water evaporation and cell disruption.
• Ecological significance of pigment diversity: Diverse pigments optimize photosynthesis for algae, providing them protection against photodamage and enhanced energy conversion. Diverse pigments also reduce competition, support biodiversity, and contribute to global carbon fixation/oxygen production.
• Microalgae as therapeutic protein factories: Microalgae efficiently produce various therapeutic proteins (hormones, cytokines, antibodies, vaccines), with the advantages of being easy to grow and lacking pathogenic components.

Test your knowledge on the biology, reproduction, and significance of algae and microalgae. This quiz covers their classification, life cycles, and various morphological features. Suitable for students and enthusiasts of biology and environmental science.