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BIOA02 Module 3 Lecture 1

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Biological Sciences
Monica Sauer

Module 3 – Lecture 1 11/03/14 Dr Robin Marushia (“Maru-sha”)/ Dr. M Office Hours: Can email request for appointment Email: [email protected] (PLEASE put my name in the title of the email as usual) SW 563B: Tuesday 2:30 – 5PM Fridays: 1 – 3PM Tree of Life: Fungi = Heterotrophic Fungus = singular Fungi = plural • Some of the primary decomposers of the earth (along with heterotrophic bateria) • Obtain carbon by breaking down organic molecules synthesized by other organisms Broken down in to two main groups (depends on how carbon is obtained) Saprotroph (Sapro = Death, Troph = to eat): From nonliving material (decomposers) Symbionts: Living organisms (either pathogens or mutualist) Symbiosis: close relationship between two organisms. Can be positive for both (mutualist) or negative (pathogens) for one. Decomposers: Breaking down nonliving organic material. Pathogens or Parasites (+/-): “infect” living organisms. Take carbon sources directly from host, host is negatively impacted by the interaction. May also act as decomposers once host is dead. Mutualists (+/+ ): Take carbon sources directly from host, but engage in mutually beneficial interaction by providing a service in return, usually providing water or nutrients from the soil. Fungi Basics: Some fungi unicellular. Most are multicellular: Primary made up of Hyphae (not roots but functions similar to roots) • Most of the fungal organism is composed of the mycelium (makes up most of biomass of any fungi individual). • hyphae (single cell strands): thread-like filaments of a fungus. Fungi's grow via apical growth, unlike plants no meristems on the side, thus can only grow longer not wider. Module 3 – Lecture 1 11/03/14 Apical growth: Hyphae grow outward by growth at tips Absorptive nutrition: As fungi extend through their environment, they secrete enzymes into their environment, breaking down large organic molecules around them into smaller components that can be absorbed into the hyphae, hyphae then transports water / nutrients via cellular streaming (no pressure) Fungi reproduce both asexually and sexually. Sexual propagules (unit that disperses to the env) are called spores. Hyphae / Mycelia Structure: Fungi, like plants, have rigid cell walls. The walls are made of chitin (similar to insects which are primary component of exoskeleton): a nitrogen-based polysaccharide. Cross walls (septa) broken apart cell wall of some hyphae into cell-like compartments Pores in the septa (or lack of septa) allow fluids in the cell to transport the water and nutrients via cytoplasmic streaming & cellular gradiance. Cytoplasmic streaming: allows nutrients to flow throughout hyphae. Reproduction: (Haploid progeny, either sexually or asexually produced, are called spores). Asexual reproduction: Hyphae cells can split off and form haploid spores, then disperses. Also, if hyphae detaches it can form a new clone individual. Sexual reproduction: three steps! • Plasmogamy: the fusion of hyphae between two genetically different individuals (not fusion of nuclei) • Karyogamy: the fusion of two sexually compatible hapoid nuclei following plasmogamy (forming a zygote (2n nucleus)) • Meiosis: the division of the diploid cell to haploid progeny following two sequential rounds of nuclear and cellular division. The progeny are spores. Module 3 – Lecture 1 11/03/14 Fungal Phylogenetic Groups: Fungi were present on Earth by at least 760 million years ago. Once they appeared, fungi radiated into se
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