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Bacterial Reproduction 02/18/
Binary Fission: One cell divides into two Tradeoff: negative correlation between two traits Advantage: rapid population growth when environmental conditions are favorable Disadvantage: no genetic variation in asexual organisms
Why is pop. growth so rapid? Do not produce gametes or zygotes, and do not undergo meiosis
Three Forms of Genetic Recombination: Conjugation o DNA transferred from donor cell to recipient cell usually through pilus (pleural: pili) Transformation o Living cell acquires DNA fragments released by dead cells Transduction o DNA fragments carried form one cell to another by viruses Akinete: large, thick walled, sugar filled celled; what’s the purpose? Heterocyte: fix atmospheric N2 into forms that can be used by organism Endospores: DNA and other materials in tough coat.
Bacterial Diversity Fossils of bacteria – 3.5 billion years old Fossils of first eukaryotic cells- 1.3 billion years old 5,000 species of bacteria recognized today. o Each species found in astronomical numbers But, difficult to classify simple once-celled organism, thus number of bacteria species uncertain. Strains of one species look alike. –subset of a bacterial species that differs from others of that species by some identifiable characteristic. Clustered by what they do
Classification of Bacteria: Nutrition Autotrophs o Produce all or most of their own organic compounds Photoautotroph o Use light as energy source for synthesis of organic compounds from CO2 and H2O, H2S, H Chemoautotrophs o Use energy obtained from chemical modification of inorganic compounds to synthesize organic compounds and CO Heterotrophs o Use organic carbon for growth by consuming other organisms
Light Dependent Reactions: chlorophyll (and accessory pigments) absorb light energy and split H20 to get an electron that goes into electron transport chain ( movement of electron down different structures) to produce ATP. – The light dependent reactions produce ATP! Light Independent Reactions: ATP is used in enzymatically driven reactions to convert CO2 into sugar. Aerobic respiration: breakdown of sugars to make ATP in the presence of oxygen (Do plants do this? Yes) – Respiration: know what’s going in Byproduct: CO2 (If plant is healthy; will take in more CO2 than release it) Using O2 to generate ATP Anaerobic photosynthesis generates sugars without producing oxygen using bacteriochlorophyll pigments. CO2+ 2H2S –with bacteriochlorophyll sugar + sulfur gas o Purple sulfur bacteria use hydrogen sulfide o Purple non-sulfer bacteria use hydrogen o Phlylum Chlorobi: green sulfur bacteria use hydrogen sulfide o Phlum Chloroflexi: green non-sulfur bacteria. Distinctions between proteobacteria and cyanobacteria Cyanobacteria have chlorophyll a and oxygen produced from photosynthesis. Cyanobacteria contain phycobilins: accessory pigments that absorb red and blue light. o Why does it absorb UV light? Protection to the cells; absorb harmful UV rays. Cyanobacteria can fix both nitrogen and produce oxygen. – convert atmospheric N2 into forms that other living organism can use. The Cyanobacteria (Blue –Green Bacteria) Cyanobacteria, chloroplast, and oxygen
o Thought that chloroplasts originated as cyanobacteria or prochlorobacteria living within other cells. o Fossils of cyanobacteria, 3.5 billion years old, found in Australia. o 3 Billion years ago, cyanobacteria produced oxygen as by- product of photosynthesis o Oxygen accumulated in atmosphere, becoming substantial 1 Billion years ago. o As oxygen accumulated, other photosynthetic organisms appeared and forms of aerobic respiration developed. o In last half billion years enough ozone for UV shield and for photosynthetic organisms to survive on land. Human relevance of the cyanobacteria: o Cyanobacteria are among the many aquatic and photosynthetic organism at the bottom of various food chains. o Often become abundant in bodies of fresh water in warmer months. Algal blooms Can be poisonous to livestock. o Food- Spirulina with significant vitamin content o Swimmers itch o Nitrogen fixation
Viruses (Not considered living!) Size and structure: about size of large molecules, 15-300 nm o Represent interface between biochemistry and life Do not grow by increasing in size or dividing Do not respond to external stimuli Cannot move on their own
Immunizations have dramatically decreased incidences of many viral diseases such as chicken pox, German measles, and mumps. o Aids Retrovirus: a virus with two identical nuclear strands. Evolves extremely quickly About a million times faster than cellular organisms. o RNA makes DNA makes RNA makes protein. o Used to infect disease organism of animals and plants Ticks, insects, possibly gypsy moths. Viroids and Prions Viroids: circular strands of RNA that occur in nuclei of infected plant cells. o Transmitted from plant to plant via pollen, ovules, or machinery Cause more than a dozen plant diseases Prions: appear to be particles of protein that cause diseases of animals and humans. o Believed to cause disease by inducing abnormal folding of proteins in brain, resulting in brain damage. Cruetzfeldt-Jacob disease Affected a lot of women when men hunted for food and they got left overs.
Protists 02/18/
Outline: Features of the kingdom Protista Evolution and relationships o “Supergroups” Excavata Alveolates Rhizaria Amoebozoa Reproductive adaptions What is a protist? Most are unicellular Bound organelles (mitochondria, chloroplasts) – Eukaryotic Heterotrophic, autotrophic, mixotrophic (both heterotrophic, and autotrophic) , Osmotrophic: absorption of nutrients through osmosis. Aquatic Mitosis to asexually reproduce (some can,some cannot) Meiosis to make gametes o Some can do both Evolutionary Relationships Taxonomic garbage dump: organisms that are not classified in plants, animals, or fungal groups.
o Ciliates Amoeboid movement – using pseudopodia o Amoebae Gliding on protein or carbohydrate slime Supergroup Excavata Related to some of Earth’s earliest eukaryotes Named for a feeding groove “excavated” into the cells of many representatives. Food particles are taken into cells by phagotrophy – ingestion of solid particles across the cell membrane o Endocytosis (processes by which cells absorb molecules) and evolutionary basis for endosymbiosis. Some are parasites o Trichomonas vaginalis (spread sexually, asymptomatic, most common std) – parasitic protist o Giardia lamblia (by drinking contaminated water diarrhea )
Green Algae (closest relatives to land plants) Define primary plastids and secondary plastids Characteristics: Marine or freshwater, unicellular, colonial, multicellular All have chlorophyll a and b and accessory pigments (UV protection) Can have flagella
Can have cell walls with cellulose (structural component of the cell wall, polysaccharide, most common organic compound on earth cellulose) Chalmydomonas, Colvax, Ulothrix, Fristschiella, Ulva, Hydrodictyon Red Algae (more closely related to green algae) Most of them are multicellular marine macroalgae Sexually reproducing, but gametes lack flagella Primary Endosymbiosis During primary endosymbiosis, heterotrophic host cells captured cyanobacteria cells via phagocytosis but did not ingest them. Endosymbiotic cyanobacteria provided host cells with photosynthetic capacity and other useful biochemical pathways and eventually evolved into primary plastids. Evidence: New mitochondria and chloroplast are formed through binary fission. In some algae, the chloroplast are destroyed or lost, the chloroplasts won’t regenerate, means that the DNA of the algae doesn’t make chloroplasts. Chloroplasts are surrounded by two (or more) membranes (Primary) o Original membrane + ingested membrane o (Secondary) – 3 membranes Both mitochondria and chloroplasts are DNA that is different from cell algae cell nucleus, similar to bacteria. (Both in size and in circular) Supergroup Alveolata (named for membrane across cell) Ciliophora
Supergroup Rhizaria Have thin, hair like extension of the cytoplasm called filose pseudopia Phylum Chlorarachiniophyta – tropical algae Phylum Radiolaria – make a test out of minerals Phylum Foraminefera – make a test (shell) out of calcium carbonate. Supergroup Amoebozoa Many types of amoebae Move using pseudopodia Entamoeba histolytica Slime molds Zygotic life cycles Most unicellular sexually reproducing protists o Tradeoffs of sexual reproduction Advantage: genetic recombination Disadvantage: require the support of structures for acquiring a mate and mating, takes energy Haploid cells develop into gametes (+) and (-) mating strains o Diploid dormant zygote develops with a tough cell wall
o Zygote undergoes meiosis and produces 4 haploid cells Thick-walled diploid zygotes o Survived like cysts If conditions are good (sufficient nitrogen) reproduce asexually. Conditions change, stimulates cells to develop into gametes. Disadvantage: only a few spores are made
Sporic life cycle Many multicellular green, red, and brown seaweeds Also know as alternation of generations 2 types of multicellular organisms o Haploid multicellular gametophyte – makes gametes o Diploid multicellular sporophyte – makes spores When mature, the diploid seaweed (sporophyte) produces spores through meiosis. Spores develop into male or female gametophyte, eggs secrete chemicals to attract flagellated sperm, fertilization produces diploid zygote, develops into mature sporophyte. o Many haploid spores can be produced
Matrotrophy: zygote is sheltered and fed within gametophytic tissue Embryophyte- all lands plants have matrotrophic embryo Produce spores
Meiosis within sporangium produces thousands of haploid spores Spores grow into gametophytes. Bryophytes have separate male and female gametophytes.
Gametophytes grow and produce gametangia at tips. If water is present, flagellate sperm are released, swim to egg and fertilization occurs. Zygote is protected and nourished by female gametophyte Embryo develops in mature sporophyte o Bryophytes (only) not land plants sporophyte retained on the female gametophyte
Lycophytes and Ferns (Seedless Vascular Plants)
Lycophytes, ferns and seed-producing plants are vascular plants or tracheophytes Possess tracheids for water and mineral conduction and structural support Vascular tissue occur in the major plant organs: stems, roots, and leaves Divered prior to the origin of seeds. Seedless vascular plants.
Tracheids: are elongated cells in the xylem of vascular plants that serve in the transport of water and minerals Xylem: transports water and some nutrients. Phloem: transports organic nutrients. (sugars) Lignin: waterproof material in cell walls of xylem Roots, stems, and leaves Stems o Contain vascular tissue and produce leaves and sporangia o Contain phloem and xylem (contains tracheids and lignin) Roots o Specialized for uptake of water and minerals from the environment o Rhizomes: a horizontal root, can send out other roots and shoots from different nodes. Leaves o Photosynthetic function.
Gymnosperms 02/18/
Plants Wood: strengthens plant, allow them to grow tall and have many branches, leaves, seeds. o Wood contains tracheids for water transport Tracheid pits on side and end walls through which water moves. Valve-like torus (porous and non-porous central region) to prevent spread of air bubbles. Pollen: allow seeds to disperse male gametophyte Ovules: protect and nourish developing embryo Seeds: allow plants to reproduce in diverse habitats (can be dispersed) Vascular cambium-meristematic tissue that produces xylem and phloem Resin ducts: help prevent attacks by pathogens and herbivores. Homosporous: spores that are the same size Heterosporous: spores of different sizes Microsprorangium: produce many small microspores (ultimately pollen) Megasporangium that produce megaspore (ultimately ovule) Ovule: structure that gives rise to and contains female reproductive cells. Sporangia – pollen cones Pollen cones (male strobili) consist of papery or membranous scales o Microsporangia in pairs toward bases of scales. Pollen – Conifers Development
Immature male gametophyte o Meiosis produces microspores that then undergo mitosis to develop into pollen grains Pollen grain consists of four cells and a pair of air sacs Air sacs add buoyancy in wind. Ovule cones Reproduction o Pair of ovules at bases of ovule cone scales o Ovule cones larger than pollen cones Have woody scales with inconspicuous bracts between. Ovules: Integuments (2n) o Integument has a pore called micropyle where pollen enters Megaspores are produced by meiosis in magasporangium- Mitosis of megaspore makes female gametophyte (megagametophyte) Gametophyte has archegonia which will produce 2 eggs (only one zygote will mature into embryo) Gametophyte accumulates large amounts of protein, lipids and carbohydrates to nourish developing embryo (seeds)
Sporophyte is dominant – produce ovule cone, pollen cone Ovule cones – megaspore undergo mitosis to produce gametophyte and egg Microspores undergo mitosis to ultimately form pollen that is dispersed into wind. Pollen grain matures into gametophyte, pollen tube deivers the sperm to the egg, fertilization occurs. Zygote develops into embryo in a seed
Reduction of gametophyte occurs as from Bryophyte Lycophytes and Seed Plants. While sporophyte gets larger.
