Presentation on theme: "The Diversity of Life Classification, Viruses, Prokaryotes, Protists and Fungi Magnet: Parts of Chapters 20-23 Honors: Parts of Chapters 17 -20."— Presentation transcript:
The Diversity of Life Classification, Viruses, Prokaryotes, Protists and Fungi Magnet: Parts of Chapters 20-23 Honors: Parts of Chapters 17 -20
Classification of organisms Taxonomy-Discipline of Bio that deals with identifying, naming, classifying, organisms –Aristotle- Grouped organisms as plants or animals Grouped animals based on habitat; plants based on structure (morphology). Believed species were fixed Linnaeus-Father of taxonomy. Classified species based on natural relationships ( behavior, structure and habitat) Systematics is a broader science that deals with taxonomy and evolutionary history Binomial nomenclature-2 word Latin name Taxons: Domain, Kingdom, Phylum, Class, Order, Family, Genus, species Species-group of organisms that are able to produce viable offspring Phyla in plants are called divisions Dichotomous keys
How are relationships determined? Evolutionary history (phylogeny). Cladistics- classifies organisms according to the order they diverged from a common ancestor. See cladograms (phylogenic trees)- p. 354. Sequences orders of organisms based on derived characters that evolved with respect to a common outgroup Development and Behavior Biochem (Nucleic acids and amino acids) and Genetics HW- What is a molecular clock?
Traditional (“old”)5 Kingdom System “Older” classification system (before domains): Kingdoms Monera, Protista, Fungi. Plantae, Animalia But now we have added domains….Monerans are now divided into 2 domains-Archeae and Bacteria. 3 rd domain is Eukarya. According to the cladogram on p. 354, which 2 domains are more closely related? Some classification systems are now dividing K. Protista into 3 kingdoms
Evidence for the 3 domain system Distinct differences in the rRNA sequence between 2 groups of prokaryotes DNA sequencing data Membrane structure Cell wall structure: bacteria cell wall is made of peptidoglycan. Archaea have proteins in their walls similar to the ones found in our membranes STUDY TABLE 20.3!!!!!!!!
Viruses Made of protein coat (capsid) and nucleic acid 5-300 nm (nm is a billionth of a meter) Why aren’t they considered “living”? No “cure”. Some can be prevented by vaccination Ex- influenza, cold, measles, mumps, HIV, hepatitis, chicken pox, herpes
Reproduction Intracellular parasites Virus attaches to host cell using their coat’s proteins and the host’s cell membrane receptors. Viral genome then enters host cell Viruses can be made of DNA or RNA---HIV is a retrovirus made of RNA Lytic cycle(active-lysis) vs. Lysogenic (inactive- virus hidden as prophage). HW-What is a prion? Give an example
Typical bacterial cell Know structure p. 63 Unicellular Prokaryotic Large circular chromosome; plasmids in nucleiod region Cell walls (peptidoglycan); Many secrete sticky substance that forms capsule outside wall. Both surround DNA. Usually 1-10 um long Cell wall prevents osmotic rupture. Penicillin breaks down cell wall and allows rupture
Bacteria continued Some use O2—others are anaerobes (may be obligate or facultative) Some are flagellated Fimbriae (once called nonsexual pili)- help bacteria to adhere to surfaces. Pili (sexual)--used for conjugation Reproduce asexually by binary fission Endospore- resistant structure with a thick, protective coat protecting a bacterium inside. Can survive for years before rehydrating. P. 369 Some bacteria have an additional outer “coat” containing lipid. Those that have it are not able to absorb a “dye” called a gram stain and are called gram -. Those without it (gram +) can absorb it and appear purple. Technique is often used in (medical) labs to differentiate types and narrow down possible diseases.
Prokaryotes are the foundation of life on earth Decompose dead organisms –Decomposers, saprobes, saprophytes Perform nitrogen fixation Live in our digestive system and are also used in the food industry –Cheese, yogurt, etc Used to decompose waste in sewage Disesase causing bacteria – Usually produce toxins. Ex- bacteria that causes botulism (paralyzes nerve cells)
Some Prokaryotes Cause Disease Bacterial Examples: cholera, diptheria, leprosy, Lyme disease, meningitis, the plague, pneumonia, sphylisis, tetanus, tuberculosis, strep throat. See p. 375 Antibiotics are the most effective means of fighting bacterial infections **No known Archaea cause disease
Major Groups of Archaea Extremophiles-3 types Methanogens- are poisoned by oxygen;use CO 2 as the electron acceptor in respiration; produces methane as a waste product Halophiles- lives in very saline places Thermophiles (aka hyperthermophiles)
Archaea Used to be grouped with bacteria and called monerans Now believed eukaryotes “split” from archaeal line of descent Archaea and Eukarya share some of the same ribosomal proteins and similar tRNA Archaea have “unusual” lipids in membrane that allow them to live under extreme conditions Cell walls composed of polysacc and some only are entirely protein. **A few recently discovered have no wall (not on test, just FYI)
The Origin of the Eukaryotic Cell Eukaryotic cells arose through a combination of 2 processes: -membrane infolding- produced all the membrane-bound organelles except the mitochondrion and the choloroplasts. –Endosymbiosis-Mitochondria and chloroplasts believed to once be prokaryotic cells that were ingested or absorbed by eukaryotic cell.
Kingdom Protista Domain Eukarya Very diverse group of organisms Most are unicellular The most elaborate cells of all the kingdoms Most are aerobic & use mitochondria for respiration Some are autotrophs, some are heterotrophs 3 types: ingestive, absorptive, photosynthetic.
Kingdom Protista Motility: flagella, cilia, pseudopodia Some reproduce sexually, some reproduce asexually - the haploid stage is the main vegetative stage of most protists; only the zygote is diploid. Zygotes undergo meiosis and become haploid (see life cycle in book) Can form cysts that survive harsh conditions Most are aquatic (plankton). What adaptation prevents them from lysing in water?
Protozoa – animal-like protists Heterotrophic and ingestive; Grouped by their means of locomotion (only know these): 1 -ciliophorans (P. Ciliophora) – move with _______; examples include Paramecium & Stentor & Blepharisma **paramecium have a macronucleus (for everyday metabolism) and micronucleus (reproduction) 2 -zooflagellates (P. Zoomastigophora) – move with ________; examples include Giardia, Trypanasoma 3 -sarcondines (**some texts: P. Sarcodina; others: P. Rhizopoda) – move with _______; examples include amoeba 4 -sporozoans (P. Apicomplexa/ P. Sporozoa) – don't move; parasitic; Plasmodium
Algae – the plant-like protists Autotrophic Classified by the pigments they contain All of the algae contain chlorophyll (photosynthetic), but some contain different types of chlorophyll and accessory pigments, causing them to appear other colors than green.
The Plant-Like Protists P. Chlorophyta – green algae - Chlamydomonas, Volvox, some seaweeds, sea lettuce P. Chrysophyta – golden-brown algae -Ex: Diatoms! Contain silica (**some books are classifying this differently now, but I am still going with this) P. Euglenophyta – Ex: Euglena (are photosynthetic, but can ingest if too deep in water to get light) P. Dinoflagellata/ P. Pyrrophyta - -dinoflagellates – cause red tide (toxic to fish)
More Plant-Like Protists P. Phaeophyta – the brown algae -include the largest seaweeds, the kelps (**multicellular) P. Rhodophyta – the red algae -include the red seaweeds, some encrusted and common in coral reefs
The Fungus Like Protists Unicellular, heterotrophic, absorbative (usually feed on decaying matter) Cell walls mainly made of cellulose (like plants). No chitin, which is found in true fungal walls Most known as slime molds or water molds When food is not plentiful, they produce spore producing structures (sporangia) and the wind disperses the spores Ex- slime molds
Lichens Look similar to some species of moss, but are not. Lichens are symbiotic associations between a fungus (often an ascomycete) and green algae or cyanobacteria The fungus usually give lichens “shelter” (optimal environment) which gives rise to their shape Alga provides the fungus with food Fungus provides a suitable physical environment for growth
What is a fungus? Heterotrophic Most are muticellular Nonphotosynthetic Digest food outside bodies (using enzymes) and absorb it some are saprophytes- live off of dead organic matter) Cell walls made of chitin.
Structure and Function of Multicellular Fungi Composed of tiny filaments called hyphae Hyphae are long strings of cells. Mass called mycelium. Some species can grow a km of hyphae/day! Can reproduce asexually by releasing haploid spores Unicellular fungi-yeast Multicellular ex: mushrooms, molds
Life cycle See supplement for life cycle of mushroom Stages of a mushroom (Basidiomycetes): –Dikaryotic (contains 2 haploid nuclei/cell) –Diploid- Haploid nuclei fuse in fruiting body of mushroom forming diploid zygote –Haploid-Zygote undergoes meiosis and forms haploid spores. Spores then germinate and fuse.
Classification Phyla: –Zygomycota- Common mold(ex-Rhizopus). Reproduce by conjugation –Ascomycota- Sac fungi; Contain ascus which are sac like structures that contain spores. Ex-Yeast, mildew –Basidiomycota-Have fruiting bodies (ex-mushroom’s cap). Contain basidium which are spore bearing repro. structures on the gills of the mushroom caps –Deuteromycota: Imperfect fungi. Sexual repro. has not been observed. Ex: Penicillium, ringworm, athletes foot
Mycorrhizae (“fungus roots”) Mutualistic associations of plant roots and fungi Almost all vascular plants have mychorrhizae
Ecological Impacts of Fungi Decomposers! Important nutrient recyclers Some are pathogens, such as ringworm and athletes foot.Plant pathogens--Dutch elm disease, Chestnut blight some produce deadly toxins-ex-some species of mushrooms we use them for their antibiotics-penicillium. Produce enzymes that rupture bacterial cell walls