BIO 104 4/4/96

Classification of Organisms
Example:
          Human          Cat
Kingdom:  Animal         Animal
Phylum:   Chordata       Chordata
Class:         Mammalia       Mammalia
Order:    Primata        Carnivora
Family:   Hominidae      Felidae
Genus:    Homo           Felis
Species:  sapiens        domestius

     One purpose of classification of organisms is to show evolutionary relationships.

Phylogenetic relationships as seen in DNA differences:
                                   % differences in nucleotide
Species                                 sequences
Human to chimpanzee                     only 1.0
Human to gibbon                              5.1
Human to old world monkey                    9.0
Human to new world monkey                    15.8
Human to lemur                          42.0

6 Kingdoms of Organisms
     1) Prokaryotes
          -archaebacteria
          -eubacteria
       Characteristics
          -no nucleus
          -circular DNA
          -cell walls composed of muramic acid
     2) Eukaryotes
          -protista
          -fungi
          -animalia
          -plantae

       Protista
          Characteristics:
          -this kingdom is based on phenetics - members are not necessarily related.
          -includes single celled organisms that carries on all life functions (or multicellular lines derived from them).
          Example:  algae, protozoa, some fungi (water molds)
          -Algae able to carry on photosynthesis, but the photosynthetic apparatus they used was probably derived from different protists.


       Fungi
          1) Unicellular (yeast) most multicellular
          2) Heterotrophic, nutrition gained through absorption.
          3) Chitin predominant in cell walls.
       Animalia
          1) Multicellular
          2) Common characteristics
               A) no cell walls
               B) heterotrophic: nutrition gained through ingestion
               C) Neurons (except Porifera)
       Plantae
          1) Multicellular
          2) Common characteristics
               A) cell walls of cellulose and other polysacharides
               B) autotrophic-photosynthetic (chlorophyll A & B)
               C) sporic meiosis (alternation of genetrations)
               D) primarily terrestrial

Differences between gametic meiosis and sporic meiosis.  See figure 25.15 (page 488 in text).
- Gametic meiosis is a life cycle typical of animals where the products of meiosis are gametes (sex
cells).
- Sporic meiosis is the life cycle found in plants where the immediate products of meiosis are
spores (which give rise to the gametophyte)

Plants
     Highlights of Plant Evolution
-plant life arose in the sea (for 1-2.5 billion years plant life was aquatic).
-ancestors like green algae (chloropyta) are thought to have given rise to the terrestrial plants
-first land plants arose during the Devonian period (early part of Paleozoic Period) 3 to 5 million
years ago
-gymnosperms (conifers) arose during the Jurassic period around 190 million years ago
-flowering plants arose during the Cretaceous period 135 million years age (dinosaurs became
extinct)

  Plants have a coevolution with insects:  because of the reproductive purpose. Flowering plants
rely on insects spreading male gametophyte (pollen) to the the female eggs in the gametophyte.