1. Viruses, Bacteria, Archaea, Protists, Fungi
Classification
Viruses, Bacteria, Archaea, Protists, Fungi

2. 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)
Binomial nomenclature-2 word Latin name
Taxa: Domain, Kingdom, Phylum, Class, Order, Family, Genus, species

3. Traditional (“old”)5 Kingdom System
Old System: 5 Kingdoms
New System: 3 Domains, 6 Kingdoms
Monera
Plant
Animal
Fungi
Protista
Eubacteria
Arachaebacteria
Eukarya
Bacteria
Arachaea
Plantae
Animalia
Fungi
Protista

4. Evidence for the 3 domain system
Molecular evidence shows that Bacteria and Archaea are actually very different
Evidence also shows that Archaea and Eukarya have many molecular similarities!!
Molecule evidence includes DNA sequencing, rRNA sequences, membrane structure, and cell wall structure

5. How are relationships determined?
Evolutionary history (phylogeny).
Cladistics- classifies organisms according to the order they diverged from a common ancestor.
Sequence orders of organisms based on derived characters that evolved with respect to a common outgroup
Development and Behavior
Biochemistry (Nucleic acids and amino acids) and Genetics

6. Bacteria

7. Bacteria Structure Unicellular, prokaryotic organisms
Large circular chromosome
Plasmids in nucleoid region
Cell walls (peptidoglycan); Many secrete sticky substance that forms capsule outside wall.
Usually 1-10 um long
Cell wall prevents osmotic rupture.

8. 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)

9. Some Prokaryotes Cause Disease: Pathogens
Bacterial Examples: cholera, diphtheria, leprosy, Lyme disease, meningitis, the plague, pneumonia, syphilis, gonorrhea; tetanus, tuberculosis, strep throat. See book for more.
Antibiotics are the most effective means of fighting bacterial infections
Penicillin breaks down cell wall and allows rupture
**No known Archaea cause disease

10. Archaea

11. Major Groups of Archaea
Extremophiles-3 examples
Methanogens: are poisoned by oxygen
use CO2 as the electron acceptor in respiration
produce methane as a waste product
Halophiles- lives in very saline places
Thermophiles (aka hyperthermophiles)

12. Archaeabacteria vs eubacteria
Used to be grouped with bacteria and called Monerans
Now believed eukaryotes “split” from archaeal line of descent
Differences between Arch and Bac:
Archaea have “unusual” diverse 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)
Similarities between Arch and Euk:
Arch and Euk share some of the same rRNA sequences and ribosomal proteins
Similar tRNA
Some Archaea have introns; bacteria do not

13. Viruses

14. Viruses: What do they look like?
Made of protein coat (capsid) and nucleic acid (DNA or RNA)
5-300 nm (nm is a billionth of a meter)
Orders of MAGNITUDE smaller than cells
(not cells)

15. Viruses: What do they do?
Intracellular parasites
Virus attaches to host cell using their coat’s proteins and the host’s cell membrane receptors.
Viral genome (DNA or RNA) then enters host cell and uses cell’s enzymes to replicate itself

16. Virus Life Cycle – lytic or lysogenic

17. Fungi

18. What is a fungus? Most are multicellular Cell walls made of chitin.
Unicellular fungi: yeast
Multicellular: mushrooms, molds
Cell walls made of chitin.
Heterotrophic
Nonphotosynthetic
Digest food outside bodies (release enzymes and absorb nutrients
Some live off of dead organic matter
Decomposers AKA Saprotrophs

19. Fungi STRUCTURE Most of the fungus is UNDERGROUND
Composed of tiny filaments called hyphae
Hyphae are long strings of cells.
Mycelium = mass of hyphae
Mushrooms are the fruiting bodies
Meaning it creates/releases the spores

20. Fungi Reproduction Can reproduce asexually by releasing haploid spores
Can also reproduce sexually by fusing hyphae of neighbor fungi
(makes a 2n organism, which then undergoes meiosis for 1n spores)

21. Ecological Impacts of Fungi
Decomposers! Important nutrient recyclers
Some are pathogens, such as ringworm and athletes foot.
Ex: ringworm, 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

22. Lichens Look similar to some species of moss, but are not!
Lichens are symbiotic associations between a fungus and a cyanobacteria (photosynthetic bacteria)
The fungus usually give bacteria “shelter”
Bacteria provides the fungus with food

23. Mycorrhizae (“fungus roots”)
Mutualistic associations of plant roots and fungi
Plant gives fungi SUGAR
Fungi gives plants NUTRIENTS
Almost all vascular plants have mycorrhizae!

24. Protista

25. Kingdom Protista Very diverse group of organisms
Most are unicellular, some multi
Most are aerobic & use mitochondria for respiration
Some are autotrophs, some are heterotrophs
3 types: ingestive, absorptive, photosynthetic.
Animal-like, Fungi-like, and Plant-like

26. Kingdom Protista 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?

27. Protozoa – animal-like protists
Heterotrophs (ingestive)
Motile (most). Classified by how they move.
4 groups:
Sarcodines: moves and ingests using pseudopodia ex: Amoeba
Ciliates: move with cilia ex: Paramecium
Flagellates: move with flagella Ex: Euglena
Sporozoans: Don’t move. Are parasitic
ex: Plasmodium
(Malaria parasite)

28. Algae – the plant-like protists
Autotrophic
Currently, classified by the pigments they contain
Green Algae Golden-Brown Algae
Volvox (single cells, colonial) Diatoms

29. The Plant-Like Protists
Dinoflagellata
dinoflagellates – cause red tide (toxic to fish)

30. 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

31. The Fungus-Like Protists
Known as SLIME MOLDS and WATER MOLDS
Unicellular, heterotrophic, absorptive (usually feed on decaying matter)
Cell walls mainly made of cellulose (like plants). No chitin, which is found in true fungal walls

32. Protists are so diverse, they’re not a “real” group
Currently being phylogenetically reclassified based on common DNA sequences, proteins, and therefore common ancestors