1. Classification of Life

2. I. Grouping Organisms
taxonomy - the field of biology that identifies and classifies organisms
taxonomists analyze shared characteristics to determine evolutionary relationships

3. I. Grouping Organisms
biological classification systems group the most closely related organisms together

4. Carl Linnaeus
Classification used today - developed by Carl Linnaeus (mid 1700’s)
Linneaus’ system originally included five levels of classification; modern scientists have added two more

5. Classification System
1. Kingdom - (most general)
2. Phyla (sing: phylum)
3. Class
4. Order
5. Family
6. Genus
7. Species (most specific)

6. Species
Members of the same species can interbreed and produce fertile offspring

7. II. The Kingdoms A. Archebacteria - extremists (prokaryotic)
B. Eubacteria - generalists (prokaryotic)
bacteria are difficult to classify,
evolutionary relationships unclear,
don’t fossilize well

8. C. Protista unicellular/multicellular eukaryotic cells not specialized
autotrophs/ heterotrophs
ex. amoeba, algae, kelp

9. D. Fungi eukaryotic multicellular have cell walls
Yeast
Mildew
eukaryotic
multicellular
have cell walls
heterotrophs - release digestive enzymes onto a food source and absorb nutrients
- ex. molds, mildews, yeast
Club Fungi

10. E. Plantae
eukaryotic
multicellular
have cell walls
autotrophs (most)

11. F. Animalia eukaryotic no cell walls heterotrophs
ex. sponges, insects, tigers

12. III. Naming Organisms
crawdad, crayfish, rock lobster all different names for the same species
clear communication among scientists around the world requires an international system for naming organisms

13. III. Naming Organisms Binomial nomenclature: two names
organisms scientific name consists of the genus name and the species name.

14. III. Naming Organisms crayfish: Cambarus bartoni
genus name is capitalized, species name lower case
name should be italicized or underlined

15. IV. Evolutionary Relationships
Phylogenetic tree shows the evolutionary relationships among organisms
more distant ancestors appear at the base
more recent relatives make up the branches

17. V. Ways to Classify 1) Structure 2) Fossil Record
3) Biochemical Analysis
(DNA sequencing, comparison of proteins)
Despite the methods of classification, it is still often difficult to classify organisms

18. V. Ways to Classify
Taxonomy constantly changes as new information is discovered and theories are refined.

19. VI. Identifying Organisms
Dichotomous key is a tool used for identifying organisms (aka biological key)
A dichotomous key lists specific observable traits.

20. VI. Identifying Organisms
For each trait, the key consists of two contrasting options.
By picking the option that matches the organisms features, you can identify organisms
Dichotomous keys are often found in field guides

21. Dichotomous Key 1a …Has feathers go to 2 1b … no feathers go to 3
2a swims… duck
2b does not swim…hen
3a has legs … lizard
3b no legs … snake OR

22. VII. Uses of Classification
Taxonomists estimate that there are million different species on Earth today and only 1.5 million species have been named and identified.
The variety in living things is called biodiversity

23. VII. Uses of Classification
Thousands of researchers study many different species
Their work can reveal unknown facts about a species.
Ex. 1994: new species of tree kangaroo discovered in New Guinea

24. VII. Uses of Classification
Also an unknown fungus was discovered. This fungus produces the drug cyclosporin which is used to prevent the rejection of transplanted organs

25. Reflection Questions
1. What are the seven levels of classification in order?
2. What is taxonomy?
3. List the six kingdoms and give at least two characteristics of each kingdom.
4. What are the different ways scientists classify organisms?
5. What is the purpose of a phylogenetic tree?