LIFE 103 Erik Arthun Class Notes - Week 3 (2/1-2/5)
LIFE 103 Erik Arthun Class Notes - Week 3 (2/1-2/5) LIFE 103
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This 7 page Class Notes was uploaded by Lauren Caldwell on Friday February 5, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Erik Arthun, Tanya Dewey in Spring 2016. Since its upload, it has received 37 views. For similar materials see Macrobiology; Plants and Animals in Biology at Colorado State University.
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Date Created: 02/05/16
2/1 Ch 31 Fungi Heterotrophys Fungi are more closely related to animals than plants Saprophytic o Digestive enzymes excreted from the surface o No stomach, they grow into their own food (they eat from the parts that are exposed to the thing they are eating) o Decomposors Symbiotic Mycorrhizae (first to come up on land), lichens Paracitic Body structure o Single cell is yeast o Many - or most, at least - are multi-cellular Allows for more ability ot absorb nutrients o Hyphae make up mycelia Hyphae -> tiny filaments with a very high surface area o Fungal walls made of chitin (thus strong but flexible) Spores o Haploid cells Different types of life cycles can still produce spores Can have a very unusual sexual cycle Diploid reproductive structures can be used to create more haploid repro structures Life cycle o Plasmogamy - union of cytoplasm from two parent mycelia Two nuclei inside of the cell Not that the nuclei fuse right away - for a long time in its life cycle, it will actually have two nuclei for a while Defined as a Heterokaryon Nuclear fusion -> the combination of the two -> can occur over hours, days, or centuries Then the organism exists as a diploid cell Then it goes through meiosis and produces haploid spores Karyogamy and meisosi (very similar to sperm and egg and their processes) results in a lot of genetic variation Often will go through asexual reproduction, but is capable of going into sexual reproduction Haploid for asexual repro - diploid for sexual repro Two different mycelium meet and they fuse (PLASMOGAMY) KARYOGAMY results in a zygote which entires meiosis Entered germination in the soil and the cycle continues on History and different types o First was a water protist o Early plants didn’t have mainstream roots Common ancestor - Chytrids (has a single flagellum) Zygomycetes o Most diverse group! Water, soil, parasites, symbiotes, etc o Molds Glomeromycetes o Symbiosis with plant roots More than 80% of plants we know have relationships with these guys Higher Fungi o Ascomycetes Can be unicellular, can be multicellular Ex: brewer's yeast, morels, lichens, penicillium (penicilin) o Basidiomycetes Mushrooms, puffballs, shelf fungi Breaks down cellulose very well Decomposers of wood Cap of mushrooms are actually there to protect the gills on the underside as they produce spores o Lichens Symbiotic Actually a product of the relatiopnship between a photosynthetic microorganism and a fungus The photosynthetic part is usually a green algae or a cyanobacteria Algae provides carbon compounds - cyanobacteria provides organic nitrogen - fungi provide the environment for growth 2/3 Chapter 29: Seedless Land Plants Before anything else, Cyanobacteria and protists were the first to appear on the earth's surface o Following that, small plants, fungi, and animals emerged on land Since colonizing land, plants have wildly diversified Plants supply oxygen and exist nearly anywhere - including all of the places human's cant survive without assistance Land plants came from Green Algae (photosynthetic prokaryotes) o Charophytes -> closest living relatives to land plants Some of its elements are retained in the land plants we see today - other elements have evolved beyond the Charophyte norm Embryophytes Plants that actually have embryos Adaptions to get to land o A lot of different characteristics are indeed shared between charophytes and land plants They lived close to the edge of ponds and lakes Lived in shallow waters Subject, as such, to occasional drying out Sporopollenin Prevents exposed zygotes (fertilized eggs) from drying out Uber important Also found in the spore walls of plants So, yes, this is a great line of evidence as to the relationship between charophytes and land plants Coming on to land allowed a lot of different niches Sunlight is no longer filtered -> now the sunlight is readily available Lots more CO2 available, as well as nutrient rich soil Challenges from coming to land Lack of water and structural support How do you retain the water? How do you keep your stalk up? o Five key traits for survival on land: Alternation of generations Unique to plants - animals don’t have it It is the alternation between two different generations based on multicellular stages Gametophyte is a haploid stage and produces haploid gametes by mitosis Like gametes (same name root) -> 1n or just n, as opposed to 2n Requires another gamete from a different plant Fertilization leads to the next stage Fusion of the gametes give rise to the diploid sporophyte, which produces haploid spores through meiosis From a zygote Undergoes meiosis, which produces spores, which develops into a gametophyte As such, the spore released leads to the next stage Multicellular, dependent embryos Diploid embryo is retained within the tissue of the female gametophyte Prevents drying out Nutrients are transferred from parent to embryo through placental transfer cells Provides things like sugars and amino acids for the embryo As such, land plants are called embryopphytes because of the dependency of the embryo on the parent Walled spores produced in sporangia All produce spores through organs called "Sporangia" Diploid cells called sporocytes undergo meiosis to generate haploid spores The spore walls contain sporopollenin That makes them resistant to harsh environments Multicellular gametangia Reproductive structures (produces gametes) Multicellular organs Female Called Produces eggs (is also the site of archegonia fertilization Male Called Produces and releases sperm (typically antheridia have flagella) Generally requires water as a method of transport 1 Apical meristems Linear growth from root and shoot tips "apex" = top Continued growth through these points Cells here will differentiate into various tissues Top side gets light and CO2 Bottom side gets water, minerals, and nutrients Elongation allows for absorbing more resources Land plants o Grouped based on the presence (or lack there of) of vascular tissue Simplest relatives to charophytes These are nonvascular plants (bryophytes) EX: Liverworts, moss, hornworts Small, herbacious plants Non-woody For all of them, gametophytes are larger and longer-living than the sporophyte stage Sporophytes are typically present only every now and then Is dependent on the gametophyte Bryophytes form a carpet ("ground-hugging" surface) Weak tissues, so it couldn't get tall Increased surface area to maximize photosynthesis Again, had no vascular tubes to transport water and nutrients o Life cycle is dominated by gametophyte stages (this is a general truth for all nonvascular plants) Key terms for life cycles Gametophyte o Is HAPOID o Produces haploid gametes Through mitosis Gametes fuse to form a diploid zygote Sporophyte o Is DIPLOID o Produces haploid spores through meiosis Haploid spores are released into the environment Which developes into the gametophyte (again, haploid) Additional traits of land plants Cuticle -> Waxy covering of the epidermic Stomata -> specialized cells on the under side of a leaf - exchanges air Mycorrhizae -> symbiotic associations between fungi and land plants that may have helped plants without true roots to obtain nutrients o Literally translates to "fungus" "root" Gametophyte = "gamete producing plant" 2/5 Bryophytes Nonvascular plants o Three groups Liverworts, hornworts, mosses Liverworts Hornworts Mosses Female gametophyte looks Sporophyte is a Sporophyte is 100% like a suessical tree (deemed prong of a sort dependent on the "liver shaped") gametophyte (bed or carpet of moss is gametophyte) Heterosporus organism -> creates two different types of spores (male or female) - a moss is a heterosporus organism Ferms are homosporus organism - each spore Mosses o Ecological importance Peat Extensive deposits of partically decayed organic material Can be used as a source of fuel CO2 stored in peat - 30% of earth's carbon here! Continued poor care of the planet can cause the CO2 stored here to be released, to accellerate the process Ferns and other seedless vascular plants o Prominent type of vegitation for a long time o Vascular tissue allowed plants to grow tall o These guys - seedless and all - have flagellated sperm that are restricted to moist environments Living vascular plants characterized by: 1. Life cycle with dominant sporophyte stage In mosses, the gametophyte is the dominant generation Otherwise, the gametophytes are tiny plants that grow on or below the soil surface 2. Vascular tissues called xylem and phloem Xylem - water (and minerals) Strengthened by LIGNIN - a molecule present that is very rigid and strong Contributes to height Allows more strength to cell walls of plants Phloem - food Sugars, amino acids, and other organic products Tubes Both: allows for increased height 3. Well-developed roots and leaves Better anchoring, allowing higher growth Evolution of Roots Anchors the plants Allows for more absorption of water and nutrients Came from subterranean steams Rhizoids DO NOT have vascular tissue (mosses) 2 Phyla of seedless vascular plants Lycophytes Monilophytes Club and spike "mosses" Ferns Not true mosses, but Horsetails look like it Used to be Quillworts used to clean pots and pants Top part (that they used) called Strobilus) o Made of leaves Whisk ferns These are things that can be found on modified leaves the Ridge The "missing link" between the bryophytes and the vascular plants Has leaves Sporophylls and Spore Variations Sporophylls are modified leaves with sporangia o Sporangia -> capsule containing haploid spores Sori are clusters of sporangia on the understides of sporophylls (grows into a gametophyte) Most are homosporus (produces one type of spore) that develops into bisexual gametophytes o Heterosporus, however: Megaspores -> female gametophytes Microspores -> male gametophytes Think about it: female eggs are generally larger, right? Micro=sperm All seed plants - and some seedless vascular plants - are heterosporus
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