Download Notes – Chapter 18

Notes – Chapter 18
Classification
I.
Taxonomy
A. Taxonomy is also known as systemic biology.
B. It is the study of classification of living things.
II.
Early Classification
A. 2000 years ago, Aristotle classified organisms as plant or animal.
B. There are 4 main reasons to classify organisms:
1. easier to study
2. organizes living things
3. explains the relationship between living things
4. it is universal
III.
Carolus Linnaeus
A. Father of Taxonomy
B. developed two Kingdom system – Plantae and Animalia
C. He grouped organisms according to shared characteristics.
D. The group was called a Taxon (plural is Taxa).
E. He used Latin to name the taxa. His real name was Carl von Linne.
IV.
Modern System
A. uses Binomial Nomenclature system to name organisms
B. uses Latinized names
C. Genus and species names always written together
1. example: Homo sapien, Canis lupus
2. example: Homo sapien, Canis lupus
V.
Three Domain System
A. domain Archaea (Kingdom Archaebacteria)
B. domain Bacteria (Kingdom Eubacteria)
C. domain Eukarya (protists, fungi, plants and animals)
VI.
Six Kingdom System
A. Kingdom Archeabacteria
1. newly added as a kingdom
2. includes bacteria- like organisms that live in extreme conditions, such as very
hot, very cold or very salty (extremeophiles)
3. prokaryotic - they have no nucleus
4. unicellular
5. mostly anaerobic – they don’t use oxygen
6. chemosynthetic – uses inorganic substances as an energy source
7. cell membranes contain unusual lipids
8. cell walls lack peptidoglycan
9. used to be included in Kingdom Monera
10.They were discovered in 1982.
B. Kingdom Eubacteria
1. prokaryotes
2. unicellular
3. includes bacteria
4. most are heterotrophic - cannot produce their own food
5. also includes blue green algae, which are also called cyanobacteria and can
produce their own food (autotrophic)
6. cells have thick, rigid cell walls, containing peptidoglycan
7. live in very diverse ecological environments
C. Protista
1. includes unicellular and multicellular organisms
2. includes the protists (Paramecium, Amoebas)
3. The protozoans are heterotrophic.
4. The brown, yellow, red and green algae are autotrophic and use photosynthesis
to produce their own food.
5. great variety of organisms within the kingdom
D. Fungi
1. They are eukaryotic.
2. The yeasts are unicellular.
3. The mushrooms, molds and mildew are multicellular, heterotrophic and
decomposers.
E. Plantae
1. They are eukaryotic, multicellular and autotrophic (photosynthetic).
2. This kingdom includes the mosses, ferns, shrubs, grasses, trees and flowers.
F. Animalia
1. They are eukaryotic, multicellular and cannot produce their own food
(heterotrophic).
2. There are both invertebrates (no backbone) and vertebrates (with a backbone).
VII.
Basis for Classification
A. Structural similarities (main basis)
B. Chromosome structure (DNA)
C. Biochemical similarities
D. Embryological development
E. Reproductive potential
F. Evolutionary history
1. uses cladistic analysis
2. considers only those characteristics that arise as lineages evolve over time
3. derived characteristics – characteristics that appear in recent parts of a lineage but
not in its older members
4. Cladograms
a. shows evolutionary relationships among a group of organisms
b. uses derived characteristics
c. helps scientists understand how one lineage branched from another
during evolution
G. Molecular Clocks
1. Uses DNA comparisons to estimate how much time two species have been evolving
separately.
2. Measures neutral mutations that have no effect on how an organism looks
(phenotype).
3. These mutations accumulate in the DNA of different species at about the same rate.
4. Comparing DNA of two species can show how different the genes are, which helps
tell how long ago the two species shared a common ancestor.
5. Molecular clocks allow researchers to time different kinds of evolutionary events.