1. PowerPoint to accompany CONCEPTS IN BIOLOGY
Enger • Ross • Bailey
CHAPTER 20
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. The classification of organisms
The problem with common names
Different in every language
Different names can be used to identify the same organism.
Organisms must have names that all scientists can identify.
Naming organisms involves two different activities.
Taxonomy
The naming of organisms
Phylogeny
Demonstrating how organisms are related evolutionarily

3. Garden snake or Garter snake?Jamestown or Jimson weed?
Then in 1676, British soldiers were sent to stop the Rebellion of Bacon. Jamestown weed (jimson weed) was boiled to be included in a salad for the soldiers to eat. The hallucinogenic properties of jimsonweed took affect.

4. Taxonomy
The science of naming organisms and grouping them into logical categories
Taxis=arrangement Taxon a grouping
Scientific names of organisms are in Latin.
Capparis cynophallophora, means “dog-penis bearing caper

5. Taxonomy Organism names follow the binomial system of nomenclature.
Introduced by Linnaeus
Uses two Latin names
The genus and the specific epithet
A genus is a group of closely related organisms.
A specific epithet identifies the particular species to which the organism belongs.
Binomial names are italicized or underlined.
The first letter of the genus is capitalized; the specific epithet is not.
Thamnophis sirtalis Cattus domesticus Homo sapiens Capparis cynophallophora

6. Taxonomy Organisms are organized into logical groups.
These groups are hierarchical.
Domain, kingdom, phylum, class, order, family, genus, species
DKPCOFGS

7. The three domains of life

8. Classification of humans

9. Phylogeny
The science that explores the evolutionary relationships among organisms.
Seeks to reconstruct evolutionary history.
Phylogenists use a variety of data to establish evolutionary relationships.
Fossils
Comparative anatomy studies
Life cycle information
Biochemical and molecular studies

10. Fossils Fossils can be placed in a time sequence.
Established by the order that the organisms appear in the layers of sediment.
Deeper layers were laid down first.
Rocks can be aged by analyzing radioactive isotopes.
Older rocks have fewer radioactive isotopes.

11. Comparative anatomy studies
The anatomy of fossilized organisms can be compared to that of living organisms.
Allows for the classification of fossils
Those organisms that have similar structures are presumed to be related.
Ontogeny recapitulates phylogeny
Examples
Plants with flowers are related.
Animals with hair and mammary glands are related.

12. Biochemical and molecular studies
New DNA technologies have allowed phylogenists to use DNA sequence comparisons to determine relatedness.

13. A current phylogenetic tree

14. A brief survey of the domains of life
Eubacteria, Archaea and EuKarya
Eubacteria and Archaea are prokaryotic.
eukarya is eukaryotic.

15. Domain Eubacteria “True bacteria” Unicellular Small (1-10 mm)
Prokaryotic (no nucleus)
Contain a single, circular chromosome
Reproduce asexually

16. Domain eubacteria Cell walls made of peptidoglycan
Can be rods, spheres or spirals
Varied metabolic requirements

17. Domain Archaea Unicellular Prokaryotic
Single circular chromosomes
Have significant differences from both eubacteria and eukarya
No peptidoglycan in their cell walls
Live in extreme habitats

18. Domain archaea Metabolically labeled as extremophiles Methanogens
Produce methane
Found in sewage, guts of ruminants, intestines of humans
Halobacteria
Live in extremely salty environments
Photosynthetic
Thermophiles
Live in high temperatures or areas with high sulfur concentrations

19. Habitat for thermophilic archaea

20. Domain Eukarya Eukaryotic
Appear to have evolved through endosymbiosis of prokaryotic cells
Larger than prokaryotes
Contain specialized membranous organelles

21. Kingdom protista Most are unicellular. Diverse
Some form colonies.
Diverse
60,000 species
Live in freshwater, marine, terrestrial
Some are parasitic, commensalistic or mutualistic.
Include algae, protozoa and slime molds
Amoeba, Paramecium

22. A diversity of protista

23. Kingdom fungi Most are non-motile
Have a thin, rigid cell wall composed of chitin
Heterotrophic
Most are saprophytes (saprotrophic) that secrete enzymes that break down the material they live on.
Decomposers
Some are parasitic, others are mutualistic.
Can form lichens

24. Kingdom fungi Most are multicellular. Made up of filaments Include
A few are unicellular.
Yeast
Made up of filaments
Include
Athlete’s foot
Plant pathogens
Ringworm

25. Examples of fungi

26. Kingdom plantae Photosynthetic Likely evolved from green algae
Green because of chlorophyll
Likely evolved from green algae
Non-vascular plants first
Then vascular
Cone-bearing
Flowering

27. Kingdom plantae Multicellular Contain a cellulose cell wall
Photosynthetic

28. Plant evolution

29. Kingdom animalia Are thought to have evolved from protozoa
Over a million species identified
Range from microscopic to very large
Common traits
Heterotrophs
Multicellular
Motile
Can reproduce sexually

30. Animal diversity

31. Acellular infectious particles
Living organisms are made of cells.
Have cell membranes
Use nucleic acids as genetic material
Have cytoplasm
Contain enzymes
Contain ribosomes
Use ATP as their source of energy
Particles that show some of these characteristics, but not all, are called acellular.
Most of these cause disease.
Viruses, viroids and prions

32. Viruses
An infectious particle consisting of a nucleic acid core surrounded by a coat of protein.
Are obligate intracellular parasites
Because they cannot live outside of a living cell
Not technically “living”
Are extremely small.

33. Typical viruses

34. Viral disease

35. How viruses cause disease
Viruses must get their nucleic acids into the cell.
Take over host cell to make more virus

36. How viruses cause disease
Viruses don’t have many enzymes.
They depend on their hosts to replicate their DNA and make their proteins.
After viruses are replicated they leave the cell.
Frequently, this process kills the cell.

37. Viral invasion of a bacterial cell

38. Prions: Infectious proteins
All prion diseases cause brain tissue to become “spongy”.
Cause spongiform encephalitis
Mad cow (BSE), scrapie (sheep), Creutzfeld-Jakob and Kuru (human)
Can be transmitted from one animal to another