Classification

Chapter 18

•  Classify – to group things together based on similarities.

•  Taxa – (taxon) categories of classification •  Taxonomy – the science or study of

classification

Reasons for classification

1. Order 2.  Sharing of traits or features

Aristotle

•  Greek Scientist / 300 BC – one of the first people to classify living things.

•  Classified into two main groups: 1. Plant – green and did not move 2. Animal – not green and did move

•  Animals were divided into groups based on where they lived. - water - land - air

•  Plants were divided into groups based on size and pattern of growth. - Tall / one trunk – tree - Medium / many trunks – shrub - Small / soft stems – herb

(ex: grass, wildflower)

On what basis did Aristotle classify plants and animals?

Structure, size, and where they lived

Carlos Linnaues

•  1735 – developed a classification system based on homologous structures. Kindgoms: Plant Animal

•  Divided living things with similar traits into groups called Species

•  Divided similar species into larger group called Genus

What 3 changes did Linnaeus make to Aristotle’s system?

1.  Classified plants and animals into more groups.

2.  Based his system on specific traits. 3.  Gave organisms names that described

their traits.

Binomial nomenclature - two word system for naming organisms. (Genus – Species)

Scientific name – all names are in latin, italicized, and include 2 names.

Today there are 7 groups for classifying organisms:

Cat Taxa Humans Animal Kingdom Animal Chordata Phylum Chordata Mammalia Class Mammalia Carnivora Order Primates Felidae Family Hominidae Felis Genus Homo Catus Species Sapiens

Today’s Classification is based on:

1)  Similar traits 2)  Ancestors or Phylogeny –

evolutionary history of organism. 3)  Body Chemistry – blood type (DNA);

Proteins; genes (gene coding)

6 Kingdom classification system:

•  Monerans – Prokaryotic, most are unicellular, heterotrophic and autotrophic. (Lack most cell parts that other cells have)

Phyla: bacteria and blue-green algae

6 kingdoms have evolved from 5. Moneran was the original Bacteria kingdom. Now there are two Bacteria kingdoms……..

1.  Archaebacteria - (“ancient”) unicellular prokaryotes with distinctive cell membranes as well as biochemical & genetic properties that differ from all other kinds of life. Live in harsh environments such as sulfurous hot springs, salty lakes, and anaerobic environments (intestines of mammals)

2.  Eubacteria – (“true”) unicellular prokaryotes that make up most of the bacteria that affect your life today. (ex: cause tooth decay, turn milk into yogurt, and cause food poisoning.

3.  Protists – eukaryotic (with some cell parts), mostly unicellular, heterotrophic and autotrophic (ex: algae, euglena, paramecium

4.  Fungi – organisms that have cell walls and absorb food from their surroundings. Eukaryotic, most are multicellular, heterotrophic (ex: mushrooms, molds, and yeast

5.  Plant – eukaryotic, multicellular,autotrophic (contains chlorophyll)

6. Animal – eukaryotic, multicellular, heterotrophic