Scientific Diversity PDF

Diversity of Microorganisms =========================== **[Early Life on Earth ]** - *Anoxic atmosphere* for the first 2 billion - Supported anaerobic organisms - Phototropic cyanobacteria increased O2 in atmosphere. - 02 \--\> 03 (ozone) absorbs UV radiation. - Aerobic c...

Diversity of Microorganisms =========================== **[Early Life on Earth ]** - *Anoxic atmosphere* for the first 2 billion - Supported anaerobic organisms - Phototropic cyanobacteria increased O2 in atmosphere. - 02 \--\> 03 (ozone) absorbs UV radiation. - Aerobic cellular respiration allowed for more efficient ATP production. **[Prokaryotic Characteristics]** - *Lack membrane-bound organelles* - Circular chromosome plasmids - Many have cell walls and capsules - Protection - Attachment - *Gram positive* vs *Gram negative bacteria* - Basis for major classification - Relative position of peptidoglycan cell wall - *Archaeal cell* walls lack peptidoglycan **[Biofilms]** - Microbial communities - Crusts or films of bacteria living on the surfaces of other objects - The *film* itself is a matrix of secreted organic molecules that binds and protect the members of the microbial community - Mixture of prokaryotes and sometimes fungi **[Reproduction in Prokaryotes]** - Binary fission: duplication of circular chromosome and splitting into daughter cells. - A bit like mitosis. - There's an absence of sexual recombination and heritable variation. - This is the primary pathway of reproduction. - Three ways prokaryotes use to create variety and bolster reproduction: - Transformation: uptake of environmental DNA. - Transduction: viral translocation from one prokaryote to another. - More indirect. - Conjugation: DNA (usually a plasmid) transfer via contact with another prokaryote. - The *closest* prokaryotes get to sexual reproduction. **[Bacteria and Disease]** - Pathogenic bacteria are the exception, *not* the rule. - All the pathogens that make us sick are bacteria. - Zoonotic diseases: transmitted from non-human animals to humans - Pandemic vs. Epidemic - An epidemic is a disease outbreak that is rapidly spreading in a limited region. A pandemic is an epidemic that is actively spreading to multiple regions across the globe - Bubonic plague - Botulism **[Antibiotic Crisis]** - Antibiotics target bacteria. - But the bacteria have been building resistance. - Overuse, incorrect use in humans. - Excessive use in agriculture - 70% of antibiotic use - Used to enhance production, not prevent disease **[Beneficial Prokaryotes]** - Fermentation - Used in the production of food and drinks - Bioremediation - Used to help in oil spills - Commensalism and Mutualism - Digestion - Competitors against pathogenic microbes - Vitamin production (K) - Training of the immune system - Around 25% of photosynthesis conducted by protists-diatoms, dinoflagellates and algae. - Zooxanthellae: mutualistic relationships with coral. - Saprophytes: decompose organic material. **[Eukaryotic Origins]** - *Lynn Margulis \--\> Endosymbiotic Theory* - Prokaryotic origins of *mitochondria* and *chloroplasts* **[Protist Origins]** - Formerly the kingdom *Protista*, but has multiple origins (not just a kingdom) - A protist is every eukaryote that can't be categorized as a plant, animal or fungus. - But they include eukaryotic *ancestors* to plants, animals, and fungi. - **Characteristics** - Aquatic or moist environments or parasitic - Motile protists move by flagella, cilia, or pseudopodia (extending their membrane and pull themselves over surfaces) - Feed via *photosynthesis* and/or *phagocytosis* via food vacuoles. - Digest food in lysosomes and expel wastes via exocytosis. **[Protist Diversity ]** - 6 monophyletic clades - Uncertainty of relationships among clades - Notable relationships - Pathogenic Protists: Humans - Malaria - Requires mosquitoes to complete life cycle. - Trypanosomes - African sleeping sickness. - Pathogenic Protists: Plants - Downy and powdery mildew - The white fuzz on fruits after leaving them around for a while. - Potato blight **[Fungi]** - Like protists, *fungi are eukaryotic---all reps in Kingdom Fungi.* - 100,000 species formally described, though likely over 1 million on Earth. - Associated with decomposition and recycling nutrients into the soil. - **Characteristics** - Once thought to be closely related to plants. - Modern DNA evidence erveals they are more closely related to animals. - Can produce *asexually*. - Spores are wind dispersed. - *Decomposers* recycle these nutrients through the ecosystem. - Interactions with other organisms (symbiotic relationships): - Mutualistic relationships: - *Mycorrhiza* -- mutualisms between plant roots and symbiotic fungi; aid in nutrient extraction from soil. - *Lichen* -- pioneer species that blanket large rocks and other exposed surfaces where most organisms can't. **[Fungi Benefits]** - Used in yeast for lots of foods that we eat and in alcohol. - Ecosystem benefits far outweigh damages. - Critical role in nutrient cycling and the "soil food web" \--\> form base of ecosystems along with plants and other decomposers. **[Fungi and Humans ]** - Parasites and pathogens: - *Mycoses* are fungal infections; typically on skin but can also be systemic (in interal organs.) - Many fungal pathogens attack plants and can damage human agriculture Diversity of Plants =================== **[What's A Plant?]** - Multicellular eukaryotes - *Flowers are more modern and are the successful groups of plants.* - Cell walls are made of cellulose. - Apical meristems: undifferentiated cells that are clustered on the end of roots or shoots that are growing and can rapidly divide and turn into anything. **[Evolution of Land Plants]** - Why move onto land? - Abundance of sunlight - Carbon dioxide (CO2) - Lack of predators - Challenges? - Desiccation - Support - Nutrient acquisition - Sexual reproduction - Adaptations to challenges? - Desiccation \--\> tolerance, waxy cuticle that keeps water from evaporating across tissues like a hydrophobic barrier. - Support \--\> cellulose (gives boxy appearance and strength) and lignin (additional carb) - Nutrient acquisition \--\> roots and vascular tissue (helps with dispersing nutrients more efficiently) - Need fungal symbiotic relationships to work at its best - Sexual reproduction \--\> pollen, seeds, embryo retention - Being taller helps with reproduction, making it harder for predators to get what they want, and better access to sunlight. **[The Plant Kingdom]** - Eukaryotes - Archaeplastida: ancestral endosymbiosis of cyanobacterium - Red algae; e.g., nori - **Remember endosymbiotic events!** - Green algae and land plants: dominance of chlorophyl, cellulose synthesis, and flagellated sperm. - Land plants: embryo retention - ALL LAND PLANTS EXHIBIT THIS! - Characteristics - Terrestrial adaptations **[Land Plant Divisions (Embryophytes)]** - Vascular Plants - Seedless plants - Lycophytes - Club and Spike Mosses - Quillworts - Pterophytes - Ferns - Whisk Ferns - Horsetails - Seed plants - Gymnosperms - Pine trees - Angiosperms - Flowering plants - The seeds of angiosperms develop in the ovaries of flowers and are surrounded by a protective fruit. Gymnosperm seeds are usually formed in unisexual cones, known as strobili, and the plants lack fruits and flowers. - Nonvascular Plants "Bryophytes" - Liverworts - Hornworts - True Mosses **[Bryophytes ]** - Bryophytes are non-vascular seedless plants - Liverworts, hornworts, and *mosses* - Limited to moist environments - Lack lignin (Lignin is a complex polymer found in the cell walls of most plants, especially wood and bark, that gives structure and support to the plant) - Anchored to rhizoids, not roots - They don't have the vascular tissues to hold in that water or the specialized tissues to do so - Sperm must *swim* to egg cells - Derived from their aquatic ancestors - Bryophytes don't have "true roots" - Life Cycle of a Moss - The life cycle of mosses alternates between the *haploid gametophyte* and the *diploid sporophyte*, called alternation of generation. - The female sex organs are known as archegonia. The male sex organ is known as antheridia. The antheridium matures to release antherozoids, which are biflagellate in structure. They swim in the water and fertilize the egg of the archegonium. The formation of the diploid zygote leads to the second life phase of mosses, the sporophyte. - Haploid stage \--\> forms sperm and eggs (green part) - Made up of individual female and male cells \--\> gametes - When fertilization occurs, there's the development of the sporophyte. - The sporophytes are cast into the environment and make rise to new female and male gametophytes. (The diploid zygote develops into a diploid sporophyte. - The diploid stage \--\> forms spores to create new plants (brief stage) **[Evolution of the Vascular Plants ]** - These that do or don't produce seeds. - Collectively, they all are characterized by the possession of vascular tissue. - Competition for sunlight favors taller growth AND vascular tissue is required for taller growth - *Xylem:* water and mineral transport; roots to shoots - *Phloem:* sugar and organic molecules; source to sink - Takes the products of photosynthesis from the leaves and sends it down to the roots for long term storage. - *True roots* and leaves support larger sizes. - Symbiosis with soil fungi -- mycorrhizae **[Vascular Continued -- Lycophytes and Pterophytes ]** - Seedless, vascular plants. - Club mosses, horsetails and ferns - Well defined leaves and root systems. - Dominant in the *carboniferous* period (359-299 mya) - coal deposits - Water still required for fertilization - Unlike bryophytes, these seedless plants can't reproduce without water as they can't pollinate. - They like environments that are good in rainfall. - Life Cycle of a Fern - Sporophytes still produce spores, and gametophytes still produce gametes. - In **mosses**, the *dominant vegetive portion of the life cycle is in the gametophytes* but for **ferns** the *sporophytes*, this is the portion of the life cycle that is associated with the *dominant vegetative portion of the life cycle*. **[Vascular Plants - Evolution of Seed Plants]** - Pollen and seeds confer relative independence from water in the absence of water. - *Pollen:* Contain sperm cells and pollen tube - Angiosperms are associated with this. - Designed for dispersal and facilitating fertilization (via wind or another animal) without water. - *Seeds:* Contain embryo and nourishment with protective seed coat. - After fertilization, allows for dormancy and early development of embryos - Because they can be dormant, they can sit around for a long time. - Gymnosperms - "Naked seed" plants because they don't bloom into fruits or flowers - Non-flowering, usually cone bearing - Needle-like leaves, often evergreen - Wind dispersed pollen - Depend upon wind for dispersal of pollen to fertilize - Types of Cones: - *Staminate cones:* Micro-sporophytes \--\> pollen - When the time is right, the pollen is carried out by the wind and goes to a tree with ovulate cones. This will bring sperm cells to the egg cells of the ovulate cones, resulting in seed forming. - *Ovulate cones:* Mega-sporophytes \--\> egg cells - Seeds form *after* pollination (successful transfer of pollen from one tree to the ovulate cone of another tree) and fertilization (the union of sperm and egg cells.) - Angiosperms - Flowers: leaves modified for reproduction - Seeds: embryo with food source (dormancy and germination (the process by which a seed or spore grows into a new plant)) - Fruits: protection and dispersal of seeds - They incentivize animals to get the seed away from the parent plant - MEMORIZE THIS! - Stamen \--\> male reproductive - Carpel \--\> female reproductive - The Angiosperm in Flowering Plants - Sepals: enclose bud, photosynthesis - Petals: attract pollinators - Stamens: male reproductive organs, produce pollen - Sperm cells x2 - Pollen tube - Carpels: female reproductive organs - Egg cells within ovules \--\> seeds after fertilization - Ovules within ovary \--\> fruit after fertilization **[Angiosperm Reproduction]** - Pollination occurs when pollen is transferred to the *stigma* - The style provides a route to *ovules*