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:
1The Diversity of LifeClassification, Viruses, Prokaryotes, Protists and FungiMagnet: Parts of Chapters 20-23Honors: Parts of Chapters
2Classification of organisms Taxonomy-Discipline of Bio that deals with identifying, naming, classifying, organismsAristotle- Grouped organisms as plants or animals Grouped animals based on habitat; plants based on structure (morphology). Believed species were fixedLinnaeus-Father of taxonomy. Classified species based on natural relationships ( behavior, structure and habitat)Systematics is a broader science that deals with taxonomy and evolutionary historyBinomial nomenclature-2 word Latin nameTaxons: Domain, Kingdom, Phylum, Class, Order, Family, Genus, speciesSpecies-group of organisms that are able to produce viable offspringPhyla in plants are called divisionsDichotomous keys
3How are relationships determined? Evolutionary history (phylogeny). Cladistics- classifies organisms according to the order they diverged from a common ancestor. See cladograms (phylogenic trees)- p Sequences orders of organisms based on derived characters that evolved with respect to a common outgroupDevelopment and BehaviorBiochem (Nucleic acids and amino acids) and GeneticsHW- What is a molecular clock?
4Traditional (“old”)5 Kingdom System “Older” classification system (before domains): Kingdoms Monera, Protista, Fungi. Plantae, AnimaliaBut now we have added domains….Monerans are now divided into 2 domains-Archeae and Bacteria. 3rd 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
5Evidence for the 3 domain system Distinct differences in the rRNA sequence between 2 groups of prokaryotesDNA sequencing dataMembrane structureCell wall structure: bacteria cell wall is made of peptidoglycan. Archaea have proteins in their walls similar to the ones found in our membranesSTUDY TABLE 20.3!!!!!!!!
6Viruses 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 vaccinationEx- influenza, cold, measles, mumps, HIV, hepatitis, chicken pox, herpes
7Reproduction Intracellular parasites Virus attaches to host cell using their coat’s proteins and the host’s cell membrane receptors. Viral genome then enters host cellViruses can be made of DNA or RNA---HIV is a retrovirus made of RNALytic cycle(active-lysis) vs. Lysogenic (inactive-virus hidden as prophage). HW-What is a prion? Give an example
9Typical bacterial cell Know structure p. 63UnicellularProkaryoticLarge circular chromosome; plasmids in nucleiod regionCell walls (peptidoglycan); Many secrete sticky substance that forms capsule outside wall. Both surround DNA.Usually 1-10 um longCell wall prevents osmotic rupture. Penicillin breaks down cell wall and allows rupture
10Bacteria continuedSome use O2—others are anaerobes (may be obligate or facultative)Some are flagellatedFimbriae (once called nonsexual pili)- help bacteria to adhere to surfaces.Pili (sexual)--used for conjugationReproduce asexually by binary fissionEndospore- resistant structure with a thick, protective coat protecting a bacterium inside. Can survive for years before rehydrating. P. 369Some 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 .
11Prokaryotes are the foundation of life on earth Decompose dead organismsDecomposers, saprobes, saprophytesPerform nitrogen fixationLive in our digestive system and are also used in the food industryCheese, yogurt, etcUsed to decompose waste in sewageDisesase causing bacteria – Usually produce toxins. Ex- bacteria that causes botulism (paralyzes nerve cells)
12Some Prokaryotes Cause Disease Bacterial Examples: cholera, diptheria, leprosy, Lyme disease, meningitis, the plague, pneumonia, sphylisis, tetanus, tuberculosis, strep throat. See p. 375Antibiotics are the most effective means of fighting bacterial infections**No known Archaea cause disease
13Major Groups of Archaea Extremophiles-3 typesMethanogens- are poisoned by oxygen;use CO2 as the electron acceptor in respiration; produces methane as a waste productHalophiles- lives in very saline placesThermophiles (aka hyperthermophiles)
14Archaea Used to be grouped with bacteria and called monerans Now believed eukaryotes “split” from archaeal line of descentArchaea and Eukarya share some of the same ribosomal proteins and similar tRNAArchaea have “unusual” lipids in membrane that allow them to live under extreme conditionsCell walls composed of polysacc and some only are entirely protein. **A few recently discovered have no wall (not on test, just FYI)
15The 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.
16Kingdom Protista Domain Eukarya Very diverse group of organisms Most are unicellularThe most elaborate cells of all the kingdomsMost are aerobic & use mitochondria for respirationSome are autotrophs, some are heterotrophs3 types: ingestive, absorptive, photosynthetic.
17Kingdom 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 conditionsMost are aquatic (plankton). What adaptation prevents them from lysing in water?
18Protozoa – 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, Trypanasoma3 -sarcondines (**some texts: P. Sarcodina; others: P. Rhizopoda) – move with _______;examples include amoeba4 -sporozoans (P. Apicomplexa/ P. Sporozoa) – don't move; parasitic; Plasmodium
19Algae – the plant-like protists AutotrophicClassified by the pigments they containAll of the algae contain chlorophyll (photosynthetic), but some contain different types of chlorophyll and accessory pigments, causing them to appear other colors than green.
20The Plant-Like Protists P. Chlorophyta – green algae Chlamydomonas, Volvox, some seaweeds, sea lettuceP. 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)
21More 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
22The 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 wallsMost known as slime molds or water moldsWhen food is not plentiful, they produce spore producing structures (sporangia) and the wind disperses the sporesEx- slime molds
23Lichens Look similar to some species of moss, but are not. Lichens are symbiotic associations between a fungus (often an ascomycete) and green algae or cyanobacteriaThe fungus usually give lichens “shelter” (optimal environment) which gives rise to their shapeAlga provides the fungus with foodFungus provides a suitable physical environment for growth
24What is a fungus? Heterotrophic Most are muticellular NonphotosyntheticDigest food outside bodies (using enzymes) and absorb itsome are saprophytes-live off of dead organic matter)Cell walls made of chitin.
25Structure and Function of Multicellular Fungi Composed of tiny filaments called hyphaeHyphae are long strings of cells. Mass called mycelium. Some species can grow a km of hyphae/day!Can reproduce asexually by releasing haploid sporesUnicellular fungi-yeastMulticellular ex: mushrooms, molds
26Life 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 zygoteHaploid-Zygote undergoes meiosis and forms haploid spores. Spores then germinate and fuse.
27Classification Phyla: Zygomycota- Common mold(ex-Rhizopus). Reproduce by conjugationAscomycota- Sac fungi; Contain ascus which are sac like structures that contain spores. Ex-Yeast, mildewBasidiomycota-Have fruiting bodies (ex-mushroom’s cap). Contain basidium which are spore bearing repro. structures on the gills of the mushroom capsDeuteromycota: Imperfect fungi. Sexual repro. has not been observed. Ex: Penicillium, ringworm, athletes foot
32Mycorrhizae (“fungus roots”) Mutualistic associations of plant roots and fungiAlmost all vascular plants have mychorrhizae
33Ecological Impacts of Fungi Decomposers! Important nutrient recyclersSome 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