General Botany & Microscopy – Comprehensive Lecture 1 Notes

INTRODUCTION TO BOTANY

  • Botany = branch of Biology devoted to the scientific study of plants.

    • Investigates plant physiology, structure, classification, ecology, distribution, genetics, economic importance.

    • Falls under Natural Science ➜ Biological Sciences ➜ Botany (with Zoology as the other major biological discipline; Physics/Chemistry/Astronomy under Physical Sciences).

  • Roles of botany for BS Biology – Medical Biology students

    • Supplies foundational knowledge of plant life processes that parallel/contrast animal systems.

    • Provides biochemical & genetic models relevant to human medicine (e.g., secondary metabolites used as drugs, model organisms such as Arabidopsis for gene function studies).

BRANCHES / FIELDS OF BOTANY (BROAD & APPLIED)

  • Agronomy – applying plant science to crop production; soil–plant relationships, sustainable yield.

  • Bryology – biology of mosses, liverworts, hornworts.

  • Economic Botany – cataloging & assessing plants with direct economic value (food, fiber, dye, timber, medicine).

  • Ethnobotany – relationships between humans & plants; traditional knowledge, cultural uses.

  • Forestry – management, conservation, & exploitation of forest resources.

  • Horticulture – science & art of cultivating garden plants; ornamentals, fruits, vegetables.

  • Lichenology – study of lichens (symbiosis of algae/cyanobacteria + fungi).

  • Phytochemistry – chemistry of plant secondary metabolites & pathways.

  • Phytopathology – plant diseases; pathogen biology; host–pathogen interaction.

  • Plant Anatomy – cellular & tissue-level structure; histology.

  • Paleobotany – fossil plants; plant evolution over geological time.

  • Plant Biotechnology – modern technological tools (genetic engineering, tissue culture, OMICS) applied to plants.

  • Palynology – pollen & spores (morphology, stratigraphy, allergies).

  • Phycology – algae (taxonomy, ecology, biotechnology).

  • Plant Breeding – hybridization & selection to create improved cultivars.

  • Plant Ecology – roles of plants in ecosystems; interactions with abiotic & biotic factors.

  • Plant Morphology – external form, life-cycle stages, organography.

  • Plant Physiology – life functions: photosynthesis, respiration, mineral nutrition, growth regulation.

  • Plant Systematics – classification schemes, phylogeny, nomenclature.

HISTORICAL DEVELOPMENT & KEY BOTANISTS

  • John Ray (1628-1705)

    • Demonstrated conduction of water through wood; early plant anatomist.

    • Member of the Royal Society (1667).

  • Carl Linnaeus (1707-1778)

    • “Father of Taxonomy.”

    • Devised binomial nomenclature; hierarchical ranks (Class–Order–Genus–Species).

  • George Bentham (1800-1884) & Sir Joseph Dalton Hooker (1817-1911)

    • Produced “Genera Plantarum” – natural system covering 92 205 spp., 7 569 genera, 200 families.

    • Based at Royal Botanic Gardens, Kew (London).

  • Charles Edwin Bessey (1845-1915)

    • Proposed phylogenetic “Bessey’s Cactus” system, integrating Darwinian evolution.

  • Adolf Engler (1844-1930) & Karl Prantl (1849-1893)

    • Engler system arranged plant families by increasing floral complexity; Prantl supplied comprehensive keys/descriptions for algae ➜ angiosperms.

Filipino contributors:

  • Asunción Raymundo – natural-product chemistry; microbial genetics for Philippine agriculture; NAST Academician; presidential adviser.

  • Eduardo Quisumbing – authority on Philippine medicinal plants & orchids; awarded Distinguished Service Star.

  • Evelyn Mae T. Mendoza – plant biochemistry of makapuno coconut phenotype; nutrient value of indigenous legumes; pest/disease resistance.

  • Prescillano M. Zamora – xylem anatomy; fern diversity; conservation policy.

  • Bienvenido O. Juliano – improved rice grain quality; methodology for grain evaluation; senior consultant, PhilRice.

  • Benito S. Vergara – photoperiodism & physiology of rice; flood- & cold-tolerant cultivars.

  • Pedro B. Escuro – breeder of high-yield, C4-type rice varieties resistant to pests/disease.

SIGNIFICANCE / APPLICATIONS OF BOTANY

  • Health care: discovery of phytomedicines & active compounds.

  • Development of new pharmaceuticals and nutraceuticals.

  • Improved planting techniques & crop yield → food security.

  • Biofuels: lignocellulosic ethanol, biodiesel from plant oils, algae bio-reactors.

  • Environmental protection: phytoremediation, carbon sequestration, habitat restoration.

CELL THEORY & FUNDAMENTAL CONCEPTS

  • Postulates:

    • All living things are composed of cells.

    • Cells are the smallest functional units of life.

    • All cells arise from pre-existing cells via division.

  • Definition: “A cell is the smallest unit capable of performing life functions.”

CELL TYPES

  • Prokaryotic

    • No membrane-bound organelles; DNA in nucleoid; single-celled (e.g., bacteria).

    • Simpler internal organization; 70 S ribosomes.

  • Eukaryotic

    • Membrane-bound organelles: nucleus, mitochondria, Golgi, ER…

    • Found in protists, fungi, plants, animals; 80 S ribosomes.

Examples: bacteria, Amoeba proteus, nerve cell, plant stem cells, red blood cells.

MAJOR EUKARYOTIC ORGANELLES (STRUCTURE→FUNCTION)

  • Plasma/Cell Membrane – phospholipid bilayer controlling traffic in/out.

  • Cell Wall – cellulose (plants) or peptidoglycan (bacteria); protection/support.

  • Nucleus – stores DNA; transcriptional control; isolated by nuclear envelope.

  • Nucleolus – ribosomal RNA synthesis & ribosome assembly.

  • Chromosomes – DNA packaged with histones; carry genetic blueprint.

  • Cytoplasm – cytosol + organelles; metabolic arena.

  • Endoplasmic Reticulum (ER)

    • Rough ER: ribosome-studded; protein synthesis/processing.

    • Smooth ER: lipid synthesis, detoxification, Ca²⁺ storage.

  • Ribosomes – sites of translation; free or bound to RER.

  • Mitochondria – ATP production via oxidative phosphorylation; regulate water & metabolite levels; involved in apoptosis.

  • Chloroplasts (plants) – photosynthesis; contain green chlorophyll; site of carbon fixation.

  • Golgi Bodies (Apparatus) – modify, package & ship proteins/lipids; vesicle trafficking.

  • Lysosomes – hydrolytic enzymes for intracellular digestion; autophagy; if ruptured, may cause cell death.

  • Vacuoles

    • Plant central vacuole: turgor maintenance, storage, waste sequestration.

    • General: membrane-bound sacs for storage/digestion.

  • Cytoskeleton – microtubules, microfilaments, intermediate filaments; cell shape, transport, division.

  • Specialized structures

    • Flagella/Cilia – motility.

    • Centrioles – spindle formation in animal mitosis.

TYPICAL CELL DIAGRAMS

  • Animal cell: nucleus, RER/SER, Golgi, mitochondria, lysosomes, plasma membrane, ribosomes.

  • Plant cell: cell wall, plasma membrane, large central vacuole, chloroplasts, amyloplasts, raphide/druse crystals, ER, Golgi, nucleus.

MICROSCOPY OVERVIEW

  • Vital instrument for cell discovery since ~1590 (first compound microscope).

  • Term derived from Latin “Microscopium,” Greek roots: micro- (small) + ‑scope (to look at).

Types based on optics:

  1. Simple Light Microscope – single lens (e.g., magnifying glass; Leeuwenhoek’s design).

  2. Compound Light Microscope – ≥2 lenses; higher magnification/resolution; common in biology labs.

Specialized light microscopy techniques:

  • Bright-field

  • Phase-Contrast

  • Dark-Field

  • Fluorescence

  • (DIC/Nomarski often grouped with phase contrast; illustrated in slides.)

CALCULATING MAGNIFICATION

  • Total magnification formula: Total Magnification=M<em>ocular×M</em>objective\text{Total Magnification} = M<em>{\text{ocular}} \times M</em>{\text{objective}}

    • Typical ocular (eyepiece) = 10×10\times.

    • Objectives: scanner (4×), low power (10×), high power (40×). Thus max total ≈ 400×400\times in standard school scopes.

PARTS OF THE TYPICAL CLASSROOM COMPOUND MICROSCOPE

Mechanical Components

  • Coarse Adjustment Knob – large, rapid stage/obj. movement; use ONLY with 4×.

  • Fine Adjustment Knob – small, precise focusing; used at 10× & 40×.

  • Stage – supports slide.

  • Stage Clips – secure slide.

  • Inclination Joint – tilts microscope (older models).

  • Body Tube – maintains correct distance between ocular & objectives.

  • Revolving Nosepiece – holds objective lenses; rotation selects magnification.

  • Base – supports instrument; hand position for carrying.

  • Arm – handle for carrying; supports optical body.

Optical Components

  • Eyepiece/Ocular – first lens viewed through; usually 10×.

  • Objective Lenses – scanner (4×), LPO (10×), HPO (40×); may include oil-immersion (100×) in advanced scopes.

  • Mirror or Illuminator (Light Source) – directs light upward.

  • Condenser & Diaphragm – concentrate/regulate light intensity & contrast.

STEP-BY-STEP USE / CARE

  1. Carry with two hands (arm + base).

  2. Place on flat surface; plug in/adjust mirror for ambient light.

  3. Start with lowest objective; bring stage near objective using coarse knob while watching from side to avoid slide breakage.

  4. Look through eyepiece; move stage down slowly until specimen comes into focus; adjust diaphragm for brightness & contrast.

  5. Switch to higher objectives by rotating nosepiece; use ONLY fine adjustment thereafter.

  6. After use: lower stage, remove slide, clean lenses with lens paper, coil cord, cover scope.

ETHICAL, PRACTICAL & PHILOSOPHICAL IMPLICATIONS

  • Responsible use of botanical knowledge to prevent biopiracy & protect indigenous intellectual property.

  • Conservation of plant biodiversity critical amid climate change & habitat loss.

  • Biotechnological manipulation (GMO crops) demands bio-safety regulations & public dialogue.

QUICK REVIEW / TAKE-AWAYS

  • Botany encompasses numerous sub-disciplines exploring all aspects of plant life, many intersecting with medicine, agriculture, and ecology.

  • Historical systems of classification inform modern phylogenetics and nomenclature.

  • Cell theory unifies biology; understanding cellular structures explains plant function and informs biotechnology.

  • Mastery of microscopy is foundational for observing cell morphology and conducting experimental biology.