1. Biological Diversity

2. Taxonomy
In chapter 26 you learned the most commonly used taxonomic scheme is as follows:
Domain
Kingdom
Phylum (Division)
Class
Order
Family
Genus
Species

3. From 5 Kingdoms to 3 Domains
This new scheme represents a change from the previous 5 or 6 kingdom scheme.
The old 5 kingdom scheme grouped all prokaryotes together: i.e. eubacteria and archaebacteria were grouped into the Kingdom Monera.
The six kingdom scheme recognized that archaebacteria were significantly different from eubacteria and should be placed into their own kingdom.

4. However, neither of these schemes showed a phylogenic relationship…i.e. how did the kingdoms evolve from an ancient ancestor.
The concept of 3 Domains was then developed and a phylogenic tree of life was created.
This tree begins with a common ancestor.

5. The Common Ancestor
The common ancestor was most likely a small, unicellular prokaryote.
It would have had Nucleic Acid (DNA or RNA) as genetic material to code for proteins
It would have had ribosomes to produce proteins
It would have been surrounded by a phospholipid bilayer
It would have used glycolysis as a means of extracting energy from glucose

6. The three domains now show that eubacteria represent one of the branches descending from the common ancestor.
The second branch divides into the archaebacteria and eukaryotes
This illustrates that archaebacteria are believed to be more closely related to eukaryotes than to the other prokaryotes.

7. Goal of Taxonomy
A major goal of taxonomy is to organize taxa on the basis of phylogeny (evolutionary relationships)
Systematics = study of the evolutionary relationships among organisms

8. Review of the Fundamental Cell Types
Eukaryotic Cells
Long, linear DNA molecule packaged into chromosomes by wrapping around histone proteins
DNA is enclosed in the nucleus
Specialized membrane-bound organelles isolate metabolic activities
Flagella and cilia, when present, are made of the protein tubulin arranged in a array.

9. Prokaryotic Cells Short, circular DNA creating a single chromosome
Many contain plasmids in addition to the major chromosome
No nucleus
No organelles (some have various membranes that serve similar functions)
Flagella, when present, consist of the globular protein flagellin

10. Domain Archaea
Archaea (Archaebacteria) are prokaryotes that differ from other prokaryotes and from eukaryotes in the following manner:
Cell walls only contain various polysaccharides, not peptidoglycans (as in bacteria), cellulose (as in plants) or chitin (as in fungi)
The phospholipids of the plasma membranes differ in their chemical structure from the phospholipids of prokaryotes and eukaryotes

11. Archaea are similar to eukaryotes
DNA of both are associated with histones (Bacteria DNA is not)
Ribosome activity of both is not inhibited by antibiotics (streptomycin and chloramphenicol) Bacteria is inhibited.

12. Domain Bacteria
Bacteria (Eubacteria): differ from archaea and eukaryotes by the following
Cell walls are made of peptidoglycan (a polymer of a monosaccharide with amino acids)
DNA is not associated with histone proteins
Ribosome activity inhibited by streptomycin and chloramphenicol

13. Domain Eukarya
Four Kingdoms: Protista, Fungi, Plantae, Animalia

14. Kingdom Protista
Protists can be animal- like, plant-like or fungus- like
Protists can be unicellular or multicellular
Determining evolutionary relationships in this kingdom is very difficult
Groupings are more morphologically based.

15. Plant-like (algaelike)
Photosynthetic protists
Euglenoids: one to three flagella, locate light for photosynthesis with an eyespot, can become heterotrophic in the absence of light.
Dinoflagellates: two flagella, spin through water, many produce a nerve toxin that is poisonous to fish, shell fish and humans: cause red tides

16. Diatoms: have shells made of silica that fit together like box lid: many shapes
Phaeophyta (brown algae) multicellular— kelp

17. Rhodophyta (red algae): multicellular with red accessory pigments (phycobilins)
Chlorophyta (green algae): unicellular, colonial, or multicellular: probably the ancestor to plants.

18. Animal-like Protists (protozoa)
Heterotrophic protists
Rhizopoda (amoebas): move with pseudopod
Foraminifera (forams): made of calcium carbonate: amoeboid protists

19. Apicomplexans (animal parasites): do not move on their own: must live within a host (malaria parasite)
Ciliates (paramecium): move using cilia: most complex: contain two nuclei

20. Fungus-like Protists
Either form filaments or spore-bearing bodies similar to the fungi.
Cellular Slime Molds: go through different life stages: spores germinate into an amoeba stage which feeds on bacteria: fungus stage in which cells unite to form fruiting bodies that produces spores

21. Plamodial Slime Molds: single spreading mass called a plasmodium feeds on decaying vegetation grows from diploid cells that arise from the joining of haploid spores.

22. Oomycota: water molds and downy mildews: form hyphae (much like fungi): cell walls are cellulose not chitin: parasitic or saprophytic
Watermold on a fish
Downy mildew on a leaf

23. Kingdom Fungi Fungi are either parasites or saprophytes
Absorb nutrients by the breakdown of products by digestive enzymes.
Their bodies consist of long filaments known as hyphae (mass of hyphae = mycelium)
Reproduce asexually by fragmentation, budding or producing asexual spores.
Six groups are identified:

24. Zygomycota: form haploid zygospores that grow into new hyphae: ex: bread mold
Glomeromycota: exist in a mutualistic relationship with plant roots ( mycorrhizae): plant provides carbs for the fungus; fungus increases the ability of the plant roots to absorb nutrients.

25. Ascomycota: produce haploid ascospores inside a structure called an ascus: Ex: Yeast, truffles
Basidiomycota: produce haploid spores in a basidia Ex: Mushrooms

26. Deuteromycota: imperfect fungi: no sexual cycle has been determined
Deuteromycota: imperfect fungi: no sexual cycle has been determined. Ex: Penicillium
Lichens: mutualistic relationship between algae and fungi. Algae provides sugar (photosynthesis); fungi provides water and improves growing conditions.

27. Kingdom Plantae
Multicellular, photosynthetic, eukaryotic organisms with cell walls made of cellulose.
Dominant generation is usually diploid
Six major divisions:
Bryophyta (mosses, liverworts, hornworts)
Lycophyta (club moss)
Sphenophyta (horsetails)
Pterophyta (ferns)
Coniferophyta (gymnosperms)
Anthophyta (angiosperms)

28. Kingdom Animalia Multicellular, heterotrophic, eukaryotic organisms
Dominant generation is diploid
Usually motile
Embryonic development involves the formation of tissue layers
Very diverse

29. Major groups of animals:
Porifera (sponges)
Cnidaria (jellyfish)
Platyhelminthes (flatworms)
Nematoda (roundworms)
Annelida (segmented worms)
Mollusca (mollusks: snails, clams, octopus )
Arthropoda (arthropods: crustaceans, insects)
Echinodermata (starfish)
Chordata (vertebrates)