BIOL 1050 Lecture Notes PDF

BIOL 1050 LECTURE NOTES Module 1 Notes Module 1: Lecture 1 Key Topics Covered Plant Reproduction Pollination Seeds and Germination Asexual Reproduction Breeding Introduction to Plant Biology The first lecture introduce...

BIOL 1050 LECTURE NOTES Module 1 Notes Module 1: Lecture 1 Key Topics Covered Plant Reproduction Pollination Seeds and Germination Asexual Reproduction Breeding Introduction to Plant Biology The first lecture introduces the three domains of life, emphasizing the importance of studying plants. Key concepts include: Taxonomy and plant families Division Magnoliophyta (Angiosperms) - flowering plants Life cycles of plants and alternation of generations Parts of a flower and the process of double fertilization The Three Domains of Life Life is categorized into three domains: Eukarya, Bacteria, and Archaea. Eukarya includes multicellular organisms such as plants, fungi, and animals. The phylogenetic tree illustrates the evolutionary relationships based on DNA sequences. Endosymbiont Theory This theory suggests that mitochondria and plastids originated from prokaryotic cells through a process called serial endosymbiosis. Key points include: Proposed ancestors of chloroplasts were photosynthetic prokaryotes. Proposed ancestors of mitochondria were non-photosynthetic prokaryotes. Evidence includes similarities in membranes, DNA transcription, and ribosome structure. Importance of Plants Plants play a crucial role in various aspects of life, including:  Oxygen production through photosynthesis Source of pharmaceuticals and food Fuel sources, including fossil fuels and biofuels Materials for fiber and enhancing quality of life through landscaping Taxonomy and Classification Swedish botanist Carl Linnaeus developed a hierarchical classification system for organisms, which includes: Kingdom Phylum Class Order Family Genus Species For example, wheat is classified as Triticum aestivum, with its family being Poaceae. Genera and Families Genera are grouped into families, which are often recognized by their common names. Examples include: Grass family (Poaceae) Sunflower family (Asteraceae) Mustard family (Brassicaceae) Latin Binomial Nomenclature Each species is given a unique Latin name to avoid confusion, consisting of the genus and species. For example, Chenopodium album L. indicates the species name and the authority (Linnaeus). Species and Subspecies A species is defined as a group of individuals that can interbreed and produce fertile offspring. Subspecies can also interbreed but may have geographical barriers preventing natural interbreeding. Cultivars are recognized subpopulations cultivated by humans. Intergeneric Hybrids These hybrids involve two different genera and require human intervention for successful breeding. New genera are named by combining the names of the parent genera, indicated by an "x". Real Examples in Guelph Examples of plants studied in the Guelph Trial Garden are: Rudbeckia, Echinacea, Echibeckia Module 1: Lecture 2 Overview of Plant Reproduction Plant reproduction involves various processes and structures, primarily focusing on the Division Magnoliophyta, also known as Angiosperms or flowering plants. These plants are characterized by unique features such as flowers, double fertilization, and fruits. They adapt to most environments, making up approximately 90% of plant kingdom diversity with over 300 families and 250,000 species. Types of Flowering Plants Flowering plants are divided into two main groups: Monocots and Eudicots (Dicots). Key differences include: Seed: Monocots have one cotyledon, while Eudicots have two. Flower Parts: Monocots typically have flower parts in multiples of three, whereas Eudicots have them in multiples of four or five. Leaves: Monocots often have parallel veins, while Eudicots have a network of veins. Root Structure: Monocots have adventitious roots, while Eudicots have a persistent primary tap root. Pollen Structure: Monocots have one pore, while Eudicots have three or more furrows. Plant Life Cycles: Alternating Generations Plants exhibit a life cycle that alternates between two generations: the diploid sporophyte (2n) and the haploid gametophyte (n). The sporophyte produces haploid spores through meiosis, which develop into gametophytes. The gametophyte produces haploid gametes via mitosis, and fertilization leads to the formation of a diploid sporophyte. In seed plants, the gametophyte is reduced and dependent on the sporophyte for nutrition. Gymnosperms and angiosperms have microscopic gametophytes within cones or flowers, respectively. Angiosperm Life Cycle The angiosperm life cycle is characterized by a dominant sporophyte phase. They are heterosporous, producing microspores (male gametophytes) and megaspores (female gametophytes). Pollen grains develop from microspores, containing a generative cell and a pollen tube cell. Upon reaching the stigma, the pollen tube grows down the style to deliver sperm to the ovule. Reproductive Structure: The Flower The flower is the reproductive shoot of an angiosperm, consisting of four main floral organs: 1. Sepals: Protect the flower bud. 2. Petals: Attract pollinators. 3. Stamens: Male reproductive organs that produce pollen. 4. Carpels: Female reproductive organs that contain ovules. Flowers can be classified as complete (containing all four organs) or incomplete (lacking one or more organs). Inflorescences are clusters of flowers. Functions of Angiosperm Reproductive Structures Flowers serve multiple functions: Produce gametes (ovule and pollen). Protect and nourish the megaspore gamete. Capture male gametes. Nourish embryos. Develop seeds and fruits. Seeds consist of an embryo, nutrient source, and protective coat, while fruits are enlarged ovaries containing seeds. Pollination Mechanisms Pollination is essential for plant reproduction, and various methods have evolved to facilitate the transfer of pollen: Biotic Pollination: Involves animals, such as insects and birds, which account for 98% of pollination. Abiotic Pollination: Involves wind and water, accounting for 2% of pollination. Pollination strategies are crucial for the successful reproduction of plants, given their immobility. Pollen Development Pollen grains develop from microsporocytes within the anthers. Each microsporocyte undergoes meiosis to form haploid microspores, which then divide by mitosis to create two-celled pollen grains. The pollen grain consists of a tube cell and a generative cell, which produces sperm cells for fertilization. The pollen grain walls contain sporopollenin, a durable material that aids in fossilization and studying the evolutionary history of seed plants. Module 1: Lecture 3 Overview of Plant Reproduction Plant reproduction involves various mechanisms and structures, primarily focusing on the flower, which serves as the reproductive shoot of angiosperms. Key concepts include: Monocot vs. Dicot Alternation of Generation Gamete Development Meiosis and Mitosis Flower Structure The flower consists of four main floral organs: Sepals (Se): Protect the flower bud. Petals (P): Attract pollinators. Stamens (St): Male reproductive organs, consisting of a filament and anther where pollen is produced. Carpels (C): Female reproductive organs, including the ovary, style, and stigma where pollen is received. Angiosperm Life Cycle The adult sporophyte phase is the main life cycle phase. Angiosperms are heterosporous, producing: Microspores: Develop into pollen grains (male gametophytes). Megaspores: Form ovules containing female gametophytes. Double fertilization is a unique process in angiosperms, where one sperm fertilizes the egg, and the other forms the endosperm. Pollination Mechanisms Pollination can occur through various methods: Insect-mediated: Dominant method, involving 80% of plants. Animal-mediated: Includes birds and bats. Wind-mediated: Less common, but effective for certain plants. Functions of Angiosperm Reproductive Structures Flowers serve multiple functions: Produce gametes (ovule and pollen). Protect and nourish the megaspore gamete.  Capture male gametes (pollen). Nourish embryos and develop seeds and fruits. Types of Flowers Flowers can be classified into: Complete Flowers: Contain all four floral organs (e.g., apple). Incomplete Flowers: Lack one or more organs (e.g., missing stamens or carpels). Inflorescence: Clusters of flowers (e.g., wild carrot). Pollination by Animals Animal pollination is crucial, with various strategies to attract pollinators: Color, nectar, and odor of flowers. Deceptive mimicry to attract specific pollinators. Common animal pollinators include: Invertebrates: Wasps, butterflies, flies, beetles. Vertebrates: Birds, bats, and other mammals. Co-evolution of Plants and Pollinators Plants and their pollinators have coevolved, leading to specialized flower shapes and structures that cater to specific pollinators. Examples include: Flowers with long nectar tubes for moths. Bird-pollinated flowers that are tubular and brightly colored. Wind and Water Pollination Wind-pollinated flowers are typically small, colorless, and odorless, producing large quantities of pollen. Key characteristics include: Flowers positioned to maximize exposure to wind. Pollen grains are smaller and drier compared to animal-pollinated species. Water can also serve as a medium for pollen transfer, although it is less common. Module 1: Lecture 4 Overview of Reproductive Strategies This lecture covers various reproductive strategies in plants, focusing on self-fertilization, cross-fertilization, and double fertilization. It also discusses the role of different pollination mechanisms and the significance of seeds and fruits in plant reproduction. Self and Cross Fertilization Reproductive strategies can be categorized into self-fertilization and cross-fertilization: Self-fertilization: Involves the transfer of pollen from the anther to the stigma within the same flower or between flowers on the same plant. Cross-fertilization: Involves the transfer of pollen from one genetically distinct plant to the stigma of another, increasing genetic diversity in offspring. Examples of Pollination Goldenrod and Ragweed are examples of plants that contribute to fall allergies, with wind-pollinated and insect-pollinated flowers. In corn, the tassel contains staminate (male) flowers, while the ear contains female flowers with silks acting as stigmas. Advantages and Disadvantages of Self-Fertilization Advantages: Widespread propagation of adapted genotypes. No reliance on wind or pollinators. Low metabolic costs and minimal wasted pollen. Disadvantages: Limited genetic diversity, which can lead to local extinction under changing conditions. Inbreeding depression and loss of vigor due to recessive alleles. Cross-Pollination Mechanisms Most plants are predominantly outcrossers, with 43% using mixed breeding systems. Mechanisms promoting cross-pollination include: Dioecious plants: Have either male or female flowers. Monoecious plants: Produce both male and female flowers with asynchronous timing of anther and carpel development. Heterostyly: Different flower morphs prevent self-pollination. Genetic incompatibility: Prevents self-fertilization through S-genes. Double Fertilization Double fertilization is a unique process in flowering plants where: A pollen grain germinates and forms a pollen tube that enters the ovary. One sperm cell fertilizes the egg cell, forming a diploid zygote. The other sperm cell fuses with the central cell, forming a triploid nucleus that develops into an endosperm. Seeds and Their Importance Seeds have significantly influenced plant evolution, becoming dominant in terrestrial ecosystems. Seeds can disperse over long distances, ensuring the survival of plant populations. A seed consists of: An embryo and nutrients, A protective coat. Germination of Ancient Seeds Researchers successfully regenerated plants from 32,000-year-old seeds found in Siberian permafrost, demonstrating the resilience of seeds. Nutritional Value of Seeds and Fruits Seeds and fruits are vital food sources for humans and animals, providing nutrients for germination and growth. Early humans recognized their value and cultivated them for food. Structure of Seeds Seeds are mature ovules containing embryonic plants. They are designed for effective dispersal and successful germination. The structure of seeds varies between dicots and monocots: Dicots: Have thick cotyledons that store food absorbed from the endosperm. Monocots: Have a single cotyledon (scutellum) and a structure called coleoptile for the shoot and coleorhiza for the root. Fruit Form and Function Botanically, a fruit is the mature ovary of a flower, protecting seeds and aiding in their dispersal. Commonly referred to fruits include: Plum, peach, grape, vegetables like string beans, eggplant, and squash are also fruits, cereals like corn and oats are classified as dry fruits. Module 1: Lecture 5 Overview of Fruits and Seeds Fruits and seeds are essential components of angiosperms, with fruits being the mature ovary of a flower. They serve to protect seeds and facilitate their dispersal through various means such as wind, water, or animals. Definition of Fruit In common language, fruits refer to juicy, edible structures like plums and grapes. However, botanically, fruits are defined as the mature ovaries of flowers. They can also include structures commonly referred to as vegetables, such as: String beans (Phaseolus vulgaris) Eggplant (Solanum melongena) Okra (Hibiscus esculentus) Squash (Cucurbita sp.) Tomato (Lycopersicon esculentum) Cucumber (Cucumis sativus) Additionally, grains like corn (Zea mays) and oats (Avena sativa) are classified as dry fruits. Classification of Fruits Fruits can be classified based on their development patterns: Simple Fruits: Develop from a single or several fused carpels of one flower. Aggregate Fruits: Formed from multiple separate carpels of one flower, e.g., raspberries. Accessory Fruits: Contain other floral parts in addition to ovaries, e.g., strawberries. Multiple Fruits: Develop from a group of flowers (inflorescence), e.g., pineapples. Simple Fruits Simple fruits can be fleshy or dry. Dry fruits can be: Dehiscent: Open to release seeds. Indehiscent: Do not open to release seeds. Aggregate Fruits Aggregate fruits develop from many separate carpels of one flower. Examples include: Raspberry Blackberry Thimbleberry Each fruit in an aggregate is a drupe containing a stony pit. Multiple Fruits Multiple fruits develop from many flowers forming an inflorescence. Examples include: Pineapple Fig The fruit of a pineapple includes tissue from the sepals and pistils of many flowers. Accessory Fruits Accessory fruits develop largely from tissues other than the ovary. For instance, the strawberry's fruit is primarily enlarged receptacle tissue, with tiny individual fruits called achenes embedded in it. Parthenocarpy Some fruits can develop without fertilization, resulting in seedless fruits known as parthenocarpic fruits. Examples include: Grapes Eggplants Navel oranges Bananas Pineapples Watermelons Parthenocarpy can be stimulated by pollination or induced through growth substances. Seed and Fruit Dispersal Effective seed dispersal is crucial for plant survival. Seeds must be dispersed widely to avoid competition with the parent plant. Dispersal agents include: Biotic (animals) Abiotic (water and wind) Dispersal Mechanisms Various adaptations have evolved for seed and fruit dispersal: Wind: Fruits may have wings or plumes to aid in dispersal. Water: Some seeds can float and survive long periods at sea, e.g., coconuts. Animals: Seeds may attach to animals or be consumed and dispersed through feces. Seed Dormancy Seed dormancy is an adaptation that allows seeds to remain viable until conditions are favorable for germination. Dormancy can be: Physical: Seed coat impermeable to water. Physiological: Requires specific environmental cues. Many seeds remain viable for years, with some lasting centuries. Germination Process Germination begins with the uptake of water (imbibition). The first sign of germination is the swelling of the radicle. Key stages include: Radicle and shoot emergence. Activation of enzymes to digest stored food. Growth of cotyledons and foliage leaves. Germination vs. Emergence Germination refers to the appearance of the radicle and shoot from the seed, while emergence is when the seedling shoot appears above the soil surface. Types of Germination In eudicots, a hook forms in the hypocotyl, pushing the cotyledons above ground (epigeal). In monocots, the coleoptile pushes through the soil, creating a tunnel for the shoot tip (hypogeal). Module 1: Lecture 6 Asexual Plant Reproduction Overview Asexual reproduction in plants allows them to propagate without the need for flowers, pollinators, or seed dispersal. This method results in offspring that are genetically identical to the parent plant, as there is no mixing of male and female gametes. Asexual reproduction is particularly advantageous in stable environmental conditions, as these plants carry the same genes as their parents. Vegetative propagation can occur through natural or artificial means, both involving the development of a new plant from parts of a single mature plant. Types of Asexual Reproduction Structures Corms: Solid tissue structures, like those of garlic, that can self-propagate. Bulbs: Layered modified leaves surrounding an underground stem, such as tulips. Rhizomes: Masses of stems, like ginger, that can produce multiple plants.  Stem Tubers: Fleshy stem structures, like potatoes, where each eye can give rise to a new plant. Stolons: Surface or underground stems, like those of strawberries, that can produce new plants. Advantages of Asexual Reproduction Requires only a single parent, allowing isolated individuals to produce offspring. Less metabolically costly than sexual reproduction, as it does not require investment in reproductive tissues. Faster reproduction rates, enabling rapid population growth. Consistency and reliability in reproduction, as it is less complicated and seldom fails. Natural Vegetative Propagation Natural vegetative propagation occurs without human intervention, allowing plants to reproduce asexually through structures such as roots, stems, and leaves. For example, in Bryophyllum and Kalanchoe, leaves develop small buds that can grow into independent plants when detached. Types of Natural Vegetative Structures Runners: Stems that grow along the soil surface, producing new plants at nodes (e.g., strawberries). Rhizomes: Horizontal stems that store nutrients and can develop into new plants (e.g., ginger, bamboo). Bulbs: Underground storage structures that produce lateral buds (e.g., tulips, daffodils). Corms: Swollen underground stems that can be cut and planted to produce new plants (e.g., gladiolas). Tubers: Swollen parts of stems or roots that store nutrients and can sprout new plants (e.g., potatoes, sweet potatoes). Suckers: Vegetative structures that grow from underground stems (e.g., bananas, raspberries). Artificial Vegetative Propagation Artificial vegetative propagation involves human intervention and includes techniques such as cuttings, layering, suckering, division, grafting, and tissue culturing. These methods are commonly used in agriculture and horticulture to clone plants with desirable traits. Methods of Artificial Vegetative Propagation Cuttings: Involves taking a part of the plant and encouraging it to root in soil or water. Layering: Bending branches to touch the ground, covering them with soil to encourage rooting. Air Layering: Wounding a branch and applying rooting hormone to encourage root growth. Division: Breaking a plant into parts, ensuring each part has roots and shoots. Grafting: Joining a desired cutting (scion) to a rooted plant (stock) to combine favorable traits. Grafting Techniques Grafting can produce unique plants with desirable characteristics. Techniques include: Chip Budding: Involves inserting a bud into the stock plant. Bench Grafting: Performed indoors with dormant stock and scion. Whip Grafting: Involves interlocking cuts on both stock and scion for a strong union. Rootstock Effects on Scions Rootstocks can influence the characteristics of the scion, including cold tolerance and disease resistance. For example, hardy rootstocks can enable the production of crops in severe climates, while resistant rootstocks can control diseases like the Phylloxera aphid in grapes. Module 1: Lecture 7 Overview of Plant Domestication Plant domestication is the process of selecting and genetically modifying plants over time to enhance traits that are beneficial for human use. This process has played a crucial role in the development of agriculture and civilization. Traits Changed During Domestication During domestication, various traits of plants are altered, including: Species-specific traits such as disease resistance. Common traits including: ○ Increased size of fruit/seed for higher productivity. ○ Loss of seed dormancy. ○ Loss of seed shattering. ○ Improved plant architecture for easier harvesting. ○ Uniform maturation of crops. ○ Reduction in undesirable flavors. ○ Loss of seeds in certain species (e.g., bananas). Teosinte vs. Modern Corn Teosinte is the wild ancestor of modern corn, characterized by small grains and a hard shell. In contrast, modern corn has larger grains and no covering. The process of domestication involved selecting for larger cobs and kernels, as well as traits that made harvesting easier. Heterosis in Plant Breeding Heterosis refers to the phenomenon where crossbred individuals exhibit superior qualities compared to their parents. This is particularly evident in corn hybrids, which are easy to produce through controlled breeding. Brassica Oleracea: One Species, Many Crops Brassica oleracea, the wild mustard plant, serves as an example of how one species can give rise to multiple cultivated varieties through selective breeding. Genetic Diversity in Plant Breeding Genetic diversity is essential for plant breeding, driven by: Crossing over during meiosis. Random fertilization of gametes. Independent assortment of chromosomes. Sources of Genetic Variability Genetic variability can arise from: Wild relatives and related species. Natural and induced mutations. Artificial hybrid crosses. Genetic transformation and gene editing techniques. F1 Hybrid Strawberry Breeding Strawberries are a major crop, with over 9 million tonnes produced annually. Day-neutral F1 hybrids are bred from seeds, reducing disease risks and increasing yields due to continuous flowering. Breeding Goals and Programs The University of Guelph's breeding program involves extensive cross-breeding and selection processes, taking up to 12-15 years to register a new cultivar. Advantages and Disadvantages of F1 Hybrids Advantages include reduced disease risk and higher yields, while disadvantages involve the need for annual seed purchases and labor-intensive cultivation. Biotechnology and Genetic Variability Biotechnology allows for the transfer of genes between organisms, creating genetically modified organisms (GMOs). Techniques include:  Agrobacterium-mediated transformation. Biolistics (gene gun). Direct DNA uptake by protoplasts. Gene editing (CRISPR). Agrobacterium-Mediated Plant Transformation Agrobacterium tumefaciens can infect plants and transfer T-DNA into their genomes, allowing for the introduction of desired traits such as insect resistance. Current GM Crops in Canada As of now, 140 plants with novel traits have been approved for food use in Canada, including varieties of corn, canola, potato, tomato, and apple. Traits of Transgenic Crops Transgenic crops are developed to ease farming, reduce pesticide use, and increase yields. Examples include: Herbicide resistance (e.g., Roundup-ready plants). Insect resistance (e.g., Bt toxin). Viral resistance. Health Benefits of Bt Technology Bacillus thuringiensis (Bt) toxin is a natural insect control method that reduces the need for chemical pesticides and has health benefits by lowering mycotoxin levels in crops. Food-Focused Transgenic Traits Transgenic crops can also focus on food quality, such as: Extended shelf life (e.g., FLAVR SAVER tomato, Arctic apple). Golden Rice, engineered to provide Vitamin A to combat deficiencies in children. Gene Editing with CRISPR-Cas9 CRISPR-Cas9 technology allows for precise modifications in DNA without introducing foreign DNA. This method has revolutionized genome editing and was recognized with the 2020 Nobel Prize in Chemistry. Potato Plant Transformation Using Gene Editing The process of potato transformation using CRISPR involves protoplast isolation, transfection, and evaluation to generate genetically modified plants.