Overview
This lecture covers the fundamentals of botany, plant cell structure, cellular reproduction, and plant tissue types, focusing on definitions, cell components, reproduction methods, and tissue functions.
Introduction to Botany
- Botany is the scientific study of plants.
- "Botane" means pasture or grass; "Botanicus" means herb or plant.
- The scope includes Pure Botany, Applied Botany, and Specialized Fields.
Scope of Botanical Study
- Pure Botany: Study of plant form, structure, development, and classification (e.g., morphology, anatomy, taxonomy).
- Applied Botany: Focuses on agriculture, breeding, pathology, and horticulture.
- Specialized Fields: Includes phycology (algae), mycology (fungi), microbiology, and bryology (mosses).
Plant Cell Structure and Organelles
- Plant cells have a rigid cell wall (cellulose), a semi-permeable membrane, and large vacuoles for turgor pressure.
- Plastids include chloroplasts (photosynthesis), chromoplasts (pigments), and leucoplasts (storage).
- Organelles: Mitochondria for ATP, ribosomes for protein synthesis, lysosomes for waste breakdown, endoplasmic reticulum and Golgi bodies for synthesis and transport.
- Nucleus controls genetic information and processes.
Cell Theory and Discovery
- Cells are the basic unit of life; all organisms are made of cells; cells arise from pre-existing cells.
- Key cell theorists: Schleiden, Schwann, Virchow.
- Robert Hooke discovered cells; Brown identified the nucleus.
Cell Division and Reproduction
- Asexual reproduction: binary fission, budding, vegetative propagation, spore formation, artificial methods (cutting, grafting, layering, micropropagation).
- Sexual reproduction involves flowers, pollination (self/cross), monoecious/dioecious plants.
- Scientific plant names follow binomial nomenclature.
Cell Cycle and Mitosis vs Meiosis
- Mitosis: One division, two identical diploid cells, somatic cells.
- Meiosis: Two divisions, four genetically different haploid cells, gametes/spores.
- Both processes include phases: prophase, metaphase, anaphase, telophase, interphase.
Plant Tissues
- Plant tissues: groups of similar cells with specific functions.
- Meristematic tissue is responsible for growth (apical for length, lateral for girth).
- Fundamental tissue types: parenchyma (storage), collenchyma (support), sclerenchyma (strength).
- Epidermis (outermost), periderm (bark, secondary growth), and specialized structures (cuticle, stomata, trichomes) protect and regulate.
- Vascular tissues: xylem (water transport) and phloem (food transport).
Key Terms & Definitions
- Botany — scientific study of plants.
- Meristem — undifferentiated plant tissue for growth.
- Parenchyma — storage tissue in plants.
- Collenchyma — cell type providing flexible support.
- Sclerenchyma — supports strength with thick walls.
- Plastid — organelle for storage and synthesis (e.g., chloroplast).
- Mitosis — cell division forming identical cells.
- Meiosis — cell division forming gametes with half chromosomes.
- Xylem — conducts water and minerals.
- Phloem — conducts food (sugar).
Action Items / Next Steps
- Review key plant cell structures and their functions.
- Practice identifying plant tissues and describing their roles.
- Prepare for next lesson on detailed plant physiology and transport systems.