PRELIMS LESSON 1: INTRODUCTION TO BOTANY
What is BOTANY?
PLANTS ARE;
ANCIENT KNOWLEDGE:
16th Century - Botanical gardens became popular 17th Century - Medicinal school in Europe was established. MODERN BOTANICAL STUDY
LESSON 2: REVIEW OF CELLS & CHROMOSOME Discovery of Cell
CELL THEORY Tenets: Matthias Schleiden, Theodor Schwann, Rudolf Virchow Cell Theory:
Cells are the basic unit of life.
Every organism is made up of cells
Every cell comes from pre-existing cells
Cells of multicellular organisms are interconnected allowing them to function as single. (Signaling Molecules & Receptors) PARTS OF THE PLANT CELL:
Cell Wall
Functions:
Primary function: to protect and provide structural support to the cell.
The plant cell wall is also involved in protecting the cell against mechanical stress and providing form and structure to the cell.
It also filters the molecules passing in and out of it.
It consists of three layers, namely, primary (growth), secondary (support) and Middle lamella (adhesion & communication
CELL MEMBRANE OR PLASMA MEMBRANE
Functions:
PHOSPOHOLIPIDS
AMPIPHATIC - being both hydrophilic and hydrophobic. MEMBRANE PROTEINS
Protoplasm (Jelly like substance) 1. Physical properties (colloid in nature) - it is transparent, colorless, slimy viscous fluid and it has the ability to absorb and eliminate water accounts for its change in viscosity. This varies from sol, a watery-like consistency to gel, a semi solid state. 2. Chemical properties - mostly made up of chemical compounds either organic or inorganic. It contains water, proteins, enzymes, salts fatty acid, and glucose. 3. Physiological properties - organisms can be distinguished from non-living matters by their functional activities. Their function attributes to the living nature of protoplasm
MITOCHONDRIA * Double membrane bound organelle / a size of 1-10 microns. * Spherical or Rod shape * Cellular Respiration: Produces a lot of ATP Functions: 1. Promoting the growth of new cells and in cell multiplication 2. Controlling various cellular activities like respiration, metabolism, cell division, and cell death 3. Maintaining an adequate concentration of calcium ions within the cell 4. Playing an essential role in apoptosis (or programmed cell death)
RIBOSOME * They are minute particles present in large numbers, either found attached to the endoplasmic reticulum or remain free in the cytosol. * Ribosomes are the protein-synthesizing center of the cell * RIbosome recycling
Functions: 1. Producing proteins required for all cellular activities including growth, metabolism and cell division
LYTIC VACUOLES (LYSOSOME) * Small membrane-bound organelles, filled with hydrolytic enzymes that can break down biomolecules such as carbohydrates, fats, and proteins. * Size of lysosomes varies among different cell types, with the largest ones measuring more than 1.2 μm * Endocytosis: Phagocytosis, Autophagy: digestion of cell components, Autolysis: Apoptotic Cell
Functions: 1. Digesting complex biomolecules such as carbohydrates, lipids, proteins, and nucleic acids 2. Destroying the organelles that are not functioning properly 3. Removing cellular waste products from the cell
VACUOLES * Large, membrane bound organelle that plays a vital role in plant cell function * It acts as a storage compartment, maintaining cell structure through turgor pressure, and is involved in diverse processes like storage, waste disposal, and protection * Many plant cells contain a single, central vacuole that can occupy a large portion of the cell volume
ENDOPLASMIC RETICULUM * RER outer surface is covered w/ ribosome. Responsible for the modification of proteins and it serves as a passageway of protein molecules. * SER involved in the synthesis of most lipids that make up the cell membrane and carbohydrates
Functions: 1. Helping in protein synthesis (RER) 2. Synthesizing essential lipids such as phospholipids and cholesterol (SER) 3. Producing steroid hormones and helping in their secretion (SER) 4. Helping in the metabolism of carbohydrates (SER) 5. Helping in the maturation of proteins (RER)
GOLGI BODIES * Also known as the Golgi body or Golgi complex, it is a series of five to eight cup-shaped, membrane-covered sacs called cisternae. * They receive proteins and lipids from RER, which are then modified, sorted, packaged, and transported to their destination.
Functions: 1. Processing, packaging and transporting or secretion of the proteins to their target organs 2. Performing protein modifications such as phosphorylation (adding phosphate group) and glycosylation (adding sugar)
CYTOSKELETON * A system of filaments or fibres that is present in the cytoplasm of eukaryotic cells * The cytoskeleton organises other constituents of the cell, maintains the cell’s shape, and is responsible for the locomotion of the cell itself and the movement of the various organelles within it
Functions: 1. Actin Filaments help determine the shape of the cell and also help it adhere to the substrate. 2. Microtubules they play in moving the daughter chromosomes during mitosis 3. Intermediate filaments are very stable structures that form the true skeleton of the cell. They anchor the nucleus and position it within the cell, and they give the cell its elastic properties and its ability to withstand tension
PLASTIDS 1. CHLOROPLAST - plastid that contain the green pigment (chlorophyll) CHLOROPHYLL - absorbs the light energy during photosynthesis. 2. CHROMOPLAST - are colored plastids that contain pigment other than green such as carotenoid (yellow), and phycoerythrin (red) 3. LEUCOPLAST - colorless plastid contains organic substances such as oil, starch, and protein
NUCLEUS * Located near the center of the cell, spherical in structure, and enclosed by the nuclear membrane.
Functions: 1. Karyoplasm or nucleoplasm is the protoplasmic content of the nucleus 2. Nuclear membrane double layer membrane that envelopes the nucleus 3. Nuclear pores are holes in the nuclear membrane that regulates the entry and exits of substances. 4. Nucleoli spherical bodies inside the nucleus, associated with the synthesis of ribonucleic acid and proteins. 5. Chromosomes a thread-like structures that bear the genes
PUTTING IT TOGETHER (MAKING PROTEINS):
LESSON 3: CELL DIVISION
ASEXUAL REPRODUCTION: * Example: Bacteria (E. Coli) * Binary Fission * The parent cell divides into 2 identical daughter cells * It does not involve sex cells or gametes - somatic cells are involved. * It’s a clone of a parent since its genome is identical to the parent cell. * It is faster and less complex compared to sexual reproduction.
TYPES OF ASEXUAL REPRODUCTION IN PLANTS:
1. NATURAL METHODS
* BUDDING
* VEGETATIVE PROPAGATION
* SPORE FORMATION
2. ARTIFICIAL METHODS
1. NATURAL METHODS: BUDDING
* New plant from outgrowth (Bud)
* Bud is formed due to cell division at one particular site.
* Eyes : small outgrowths that be planted individually
2. NATURAL METHODS: VEGETATIVE PROPAGATION:
1. STEM (RUNNERS) - These stems grow horizontally above the ground. Buds grow in the stem node and usually grow as a new plant.
2. ROOTS (TUBERS) - these modified roots store nutrients and become enlarged. Each of these may give rise to a new plant.
3. LEAVES (PLANTLET) - these miniature plants grow in the leaf margin and when the roots develop, they detach in the leaf and grow as a new plant.
3. NATURAL METHODS: SPORE FORMATION * MOSS and FERN use this mode of reproduction * Spore: is a reproductive body to withstand unfavorable conditions.
1. ARTIFICIAL METHODS: CUTTING
* A part of the plant is cut and buried. This requires frequent watering until the roots develop.
2. ARTIFICIAL METHODS: GRAFTING
* The parts of two different plants are joined together such that they continue growing as a single plant
3. ARTIFICIAL METHODS: LAYERING
* A plant's stem lowered to the ground and covered with soil. The roots will develop and the stem will grow as a new plant.
4. ARTIFICIAL METHODS: MICROPROPAGATION
* This facilitates the growth of rare and endangered plant species that are difficult to grow under natural conditions
* It involves tissue culture or cell culture techniques multiplying genetic replicas of plants that are referred to as clonal propagation.
SEXUAL REPRODUCTION IN PLANTS: * FLOWER STRUCTURE: Calyx (sepals), corolla (petals), androecium (male part), and gynoecium (female part). * COMPLETE: Have both the Male & Female gametophytes (Androgynous - part male part female, or Hermophroditic - hard to say if male or female E.g hibiscus & tulips) * INCOMPLETE: contain Male or Female gametophytes is present. E.g. cucumbers, hydrangeas, and rue-anemone flowers * Staminate: contains male structure * Carpellate - contains female structure * POLLINATION: Is the transfer of pollen grains from the anther (male part) to the stigma female part of the plant of the same species. * Self-pollination & Cross-pollination
MONOECIOUS VS DIOECIOUS * Monoecious - BOTH staminate and carpellate flowers are found together on the same plant (e.g., corn). * Dioecious - staminate flowers occur on separate plants from those that carry carpellate flowers (e.g., date palms)
PLANT GROWTH: * Plant growth increases its size mostly in length. * CELL GROWTH - increases in cell size. * CELL DIVISION - Increases in cell number * MERISTEM - A type of tissue consisting of undifferentiated cell (meaning it is not specialized like xylem or phloem cells) is the key for plant development of leaves and flowers.
SCIENTIFIC NAMES OF PLANTS 1. gumamela: Hibiscus rosas-sinensis 2. potato: Solanum tuberosum 3. Strawberry - Fragaria ananssa 4. Air Plant - Bryophyllum pinnatum 5. Pako Fern- Diplazium esculentum 6. Cucumber - Cucumis sativus 7. Hydrangea - Hydrangea Macrophylla 8. Papaya - Carica papaya 9. Corn - Zea mays
CELL DIVISION * A process where cells undergo division resulting in the formation of new daughter cells * It enables sexually reproducing organisms to develop from one-celled zygote, which itself was produced by cell division from gametes * The continuation of species from generation to generation is governed and insured by the union of cells and the division of the cells.
CELL CYCLE * Series of events in which the mother cells divide producing new daughter cells. These new cells will mature and perform their functions and divide again. * Stages: * M PHASE: mitosis (karyokinesis & cytokinesis) * Interphase: is a time when the cell grows and engages in diverse metabolic activities. * Cell cycle arrest: some parts of the plant matures and reach their final form then it would stop dividing
MITOSIS VS MEIOSIS
MITOSIS: * 2 DIPLOID CELLS (2N) * SOmatic cells - body cells * Involve one cell division/cycle * Daughter cells and identical * Cells have 46 chromosomes * Occurs in all organism except viruses
MEIOSIS * 4 Haploid daughter cells (N) * Reproductive cells - gametes in animals; spores in plants * Involves two successive cell division (Meiosis 1 and Meiosis 2) * Daughter cells are genetically different * Cells have 23 chromosomes * Occurs in animals, fungi, & plants
SIMILARITIES: * Cells undergo DNA replication * PRoduces new cell * Starts with diploid parent cell * Occurs in plant and animals
STAGES OF MITOSIS
1. PROPHASE:
* EARLY: Shortening, coiling, doubling, thickening of the chromosomes.
* MIDDLE: Disappearance of nuclear membrane & Nucleolus
* LATE: Microtubules are organized to form spindle fibers. Doubled chromosomes called sister chromatids are visible.
2. METAPHASE (STAGE OF SEPARATION)
* EARLY: Alignment of the chromosomes at the center (metaphase plate/ equatorial region)
* LATE: separation of the sister chromatids.
ANAPHASE (STAGE OF MIGRATION * This begins just after the centromere divides and each chromosome separates. * EARLY: chromatids move to opposite poles * LATE: chromatids have reach each pole.
TELOPHASE (CYTOKINESIS) * The chromosome group at the ends of the spindle fiber * EARLY: assembly of the chromatids at each pole, formation of cell plate or phragmoplast in plants at the equatorial plate. * LATE: separation of two new daughter cells, reappearance of nuclear membrane and nucleolus.
INTERPHASE * GAP 1 (G1) * Cell recovery * Performs metabolic processes * Synthesis of nucleotide (for next step- cell division) * SYNTHESIS PHASE (S) * DNA replication * Higher plants and animals need about 100,000 types of genes to store all information * Complex of gene is called a genome * GAP 2 PHASE (G2) * Preparation of cell division * Alpha & Beta tubulin is necessary for the spindle microtubule is synthesized * Cells are believed to produce proteins needed for processing chromosomes and breaking down nuclear membranes.
MEIOSIS
MEIOSIS I
INTERPHASE I : * Involve sperm cell and egg cell with 23 chromes during fertilization. * The process is similar to interphase in Mitosis. The DNA from each parent will duplicate in S Phase and form 2 identical copies called sister chromatids * In meiosis I they are pulled together by the centromere and pulled apart in meiosis II.
PROPHASE I: * Same process in mitosis but involves homologous chromosome which is the pairing of sister chromatids called Synapsis Sister chromatids: Duplication of each parent’s chromosome from each parent. Homologous chromosomes: pairing of sister chromatids from each parent.
* Genes on the chromatids of the homologous chromosomes are precisely aligned for the crossing over
Crossing over: the exchange of genetic material from both chromatids
PROMETAPHASE I * Same process occurs in late prophase in Mitosis. * Kinetochore protein buds with the spindle fiber and the recombinant chromosome (sister chromatids) separate * Tetrad: Alignment of 2 sister chromatids
PROMETAPHASE I * Same process occurs in late prophase in mitosis * Kinetochore protein binds with the spindle fiber and the recombinant chromosome (sister chromatids) separate * Tetrad: alignment of 2 sister chromatids
Chiasmata - point of contact of the non-sister homologous chromosome.
METAPHASE I * Recombinant chromosomes are randomly aligned plates. * Independent assortment (genetics variation for organisms): physical basis for the generation of the second form of genetic variation in offspring .
ANAPHASE I * Recombinant chromosomes are pulled to opposite poles of the cell by the spindle fiber.
TELOPHASE I * Recombinant chromosomes arrived at the opposite poles * Formation of cleavage furrow or cell plate of phragmoplast in plants * No DNA replication in Interkinesis
MEIOSIS II
* Meiotic-mitotic division: the process is similar to mitosis
PROPHASE II * Cells have one chromosome from each homologous pair.
METAPHASE II * Chromosomes align at the metaphase plate, the centromere divide, thereby separating each chromosome from its replicate.
ANAPHASE II * Each daughter chromosome moves to opposite poles.
TELOPHASE II * Spindle fibers disappear. * Nuclei are formed and cytokinesis takes place. Each nucleus contains just one set of chromosomes with a single chromatid. * Four haploid daughter cells are produced.
MIDTERMS
LESSON 4: PLANT TISSUES
WHAT ARE PLANT TISSUES? * A group of cells that perform the same function and are commonly similar in structure. * Simple Tissue - similar cells with specific functions. (E.g. Fundamental tissues) * Complex Tissue - is composed of several types of cells. (E.g Vascular tissue) * In a plant body, an organ is composed of various tissues grouped together to perform interrelated functions. * Plant tissues are characterized and classified according to their structure and function. A good example are the three basic tissue patterns found in roots and stems. This serves to delineate between woody dicot, herbaceous dicot, and monocot plant.
THREE BASIC TISSUE PATTERNS (FOUND IN ROOTS AND STEMS): * Fundamental, Surface, and Vascular TIssue
MERISTEMATIC TISSUE (EMBRYONIC TISSUE) * These are immature & undifferentiated cells that are usually small, thin walled, approximately isodiametric cells w/ large nucleus and lack of large vacuoles. * Intercellular spaces are absent. * Located mostly in regions of active cell division (mitosis)
APICAL MERISTEMS (VERTICAL GROWTH IS KNOWN AS PRIMARY GROWTH) * Located at/or near the tips of roots and shoots responsible for length. * This will produce embryo leaves and buds as well as three types of primary meristems (Tissues): * Protoderm (dermal tissue - protecting tissue) * Ground meristems (Ground tissues - support tissue) * Procambium (Vascular tissues - conducting tissue)
LATERAL MERISTEMS (HORIZONTAL GROWTH IS KNOWN AS SECONDARY GROWTH) * Located at the lateral side of the shoot that increased girth or width (Thickness). * Two types of lateral meristems (Tissues) * Vascular cambium (Cambium) * Cork Cambium
VASCULAR CAMBIUM (CAMBIUM) * It is a thin, branching cylinder that runs the length of the roots and stems of most dicot plants. * Located between the primary phloem & primary xylem in shoots and roots * Increase the thickness, or girth of the plant.
Formation of Secondary growth * Cells in the vascular cambium divide and form secondary phloem (sieve tubes & companion cells) * These appear between the primary xylem & phloem * Secondary xylem towards inside the cambium ring while, * Secondary phloem towards the outside of the cambium ring. * The cells of the secondary xylem contain lignin, the primary component of wood which provides strength & structural support * The xylem together with the pith form the wood of a woody stem
ANNUAL RINGS * Annual rings in plants are formed due to seasonal variations in the activity of vascular cambium. * The activity of the vascular cambium is affected by physiological and environmental factors.
CORK CAMBIUM (BARK) * Found only in woody dicots and in the outermost lateral meristem. * Produces cork cells which contain a waxy substance (suberin) that can repel water. * Phloem together w/ cork cells form the bark that protects the plant against physical damage & helps reduce water loss.
* It also produces a layer of cells known as Phelloderm, that grows inward from the cambium.
* The cork cambium, cork cells, and phelloderm are collectively termed the periderm
* (Epidermis in woody dicot plants)
INTERCALARY MERISTEMS * Found in grasses and related plants. * Also, found in the intermodal space of space near the nodes of plants * These meristem produce new cells and are responsible for increases in length * This is responsible for the regrowth of cut grass
PERMANENT TISSUES (MATURE TISSUE):
FUNDAMENTAL TISSUES * Termed also as the Ground tissue. * Parenchyma - Storage * Collenchyma - Flexible support * Sclerenchyma - strength & support
PARENCHYMA * Location: almost all major parts of higher plants (most abundant cell). E.g. Stem, Roots, Leaves & Fruits * In leaves called chlorenchyma because of the presence of chloroplast involved in photosynthesis. * Structure: spherical in shape, thin walls, and flattened * With large vacuoles and may contain various secretions including starch, oils, tannins, and crystals * Functions: Storage of food and water repair of damaged tissue when it gets mature.
Palisade Parenchyma: elongated and with more chlorophyll Spongy Parenchyma: spherical or ovoid and with a few chlorophyll and air spaces
COLLENCHYMA * Location: stem, leaves, & flowers * Structure: w/ irregular thickened cell wall due to the deposition of pectate substances and cellulose * Functions: provide flexible support for organs.
SCLERENCHYMA * Location: Stem, leaves, & flowers * Structure cells have thick, tough secondary walls that are embedded with lignin. * Functions: provide structure, strength, and support at maturity (dead)
SCLERENCHYMA
Two Forms:
1. Schlereids/Stone cells: generally long as they are wide, nearly spherical, rod-like filamentous. Form the major portion of seed coat and nut shells and the masses of gritty pulp of pearls and apples
* Provides strength and support
*
2. Fibers: found in roots, stems, leaves, and fruits. Usually much longer and have tapering ends.
* Posses great strength and elasticity
SECRETORY CELLS AND TISSUES * These are parenchyma cells. * It accumulates substances as a result of cellular processes. * Most of the substances are oils in citrus, pine resin, latex, opium, nectar perfumes, and plant hormones
SURFACE TISSUES OF PLANTS
EPIDERMIS * Outermost layer of cells on all plant organs (root, stem, leaves). * It has a direct contact with the environment therefore is subject to environmental conditions & constraints * Generally is one layer thick, however, there are exceptions like tropical plants where the layer may be several cells thick and thus act like a sponge.
* Cutin a fatty substance secreted by most epidermal cells, forms a waxy protective layer called the cuticle.
* The thickness of the cuticle is one of the determiners how much water is lost by evaporation
* Stomata are small pores that occur in the epidermis and are surrounded by pairs of specialized cells called guard cells.
* This is used for the exchanged of gases from and into the leaves
* Trichomes are modified epidermal cells that may be glands or hairs that repels insects or reduce water loss
* It can be uni, multicellular, epidermal outgrowth
* Often much branched & sometimes glandular secreting oils & other substances
PERIDERM (SECONDARY GROWTH) * In woody plants, when the cork cambium begins to produce new tissues to increase the girth of the stem or root the epidermis is sloughed off (peeling) and replaced by periderm. * Periderm is made of semi-rectangular or boxlike like cork cells/phellem . This will be the outermost layer of the bark and dead at maturity. * The outer walls of the cork cell are deposited by the suberin
* Suberin - This makes cork cells waterproof or impermeable to any substances and aids in protecting tissues beneath the bark.
* Lenticels - are parts of cork cambium that are pockets of loosely packed cork cells that do not have suberin
* This function in gas exchange between the air and the stem interior
PERIDERM VS EPIDERMIS * The epidermis is the outer layer of leaves, young stems, and young leaves, whereas the periderm is the outer layer of roots and stems that have undergone secondary growth.
VASCULAR TISSUES OF PLANTS
XYLEM: * iPrincipal water-conducting tissue of the plant. * It carries water and dissolved substances throughout the plant and consists of a combination of Parenchyma cells, fibers, vessels, and tracheids * Tracheids and vessel elements are the main conducting tissue of xylem
* Xylem parenchyma – stores starch, oils, and many other ergastic substances.
* Xylem sclerenchyma – comprised of fibers that are long cells w/ secondary lignified walls that provide support and strength to the tissue
* Vessels – are longitudinal series of long tubes connected to each other to form long tubes
* Tracheids – have thick secondary walls and do not have openings. It has overlapping pairs of pits and this allows water to pass from cell to cell.
PHLOEM: * It’s the food-conducting tissue of plants and it carries dissolved food substances throughout the plant * This is composed of sieve-tube member and companion cells that are without secondary walls, parenchyma cells, and sclerenchyma cells.
PHLOEM * Sieve tubes – are formed from sieve-tube members laid end to end and do not have openings * The end walls, however, are full of small pores where cytoplasm extends from cell to cell. * These porous connections are called sieve plates where dissolved substances are able to move from one sieve tube to another * Companion cells – are special parenchyma cells that are nestled between sieve-tube members that helps in the translocation of food * Phloem Parenchyma – serves as storage of ergastic food such as starch, tannins, crystals etc. * Phloem sclerenchyma – present in primary and secondary phloem that provide support and strength to the tissues
COMPARISON IN STRUCTURE
SUMMARY: