Overview of Classification 2 Chapter 18

Kingdoms Linnaeus only had 2 kingdoms – Plantae and Animalia. Scientists decided there were organisms that didn’t fit it those. They came up with a 5 kingdom system – Monera, Prostista, Fungi, Plantae, and Animalia.

They then decided to break Monera into 2 groups They then decided to break Monera into 2 groups. It was broken into Eubacteria and Archaebacteria. The current kingdoms are: Eubactieraa, archaebacteria, Protista, Fungi, Plantae, and Animalia.

Domain System New evolutionary studies looked a rRNA similarities. This has given a new taxonomic category – the domain. Domain is a larger category than kingdom. There are 3 domains: Eukarya (has protists, fungi, plants, and animals), Bacteria (which has the eubacteria in this group), and Archaea (contains organisms in kingdom Archaebacteria).

Domain Bacteria Members in this group are unicellular and prokaryotic. They have thick, rigid cell walls around their cell membrane. This domain includes all organisms in the kingdom Eubacteria. They are very diverse living in different areas and needed different things.

Domain Archaea These bacteria are also unicellular and prokaryotic. These live in extreme environments like volcanic hot springs, brine pools, and black organic mud that has no oxygen. Many of these bacteria can only live in oxygen free areas.

Domain Eukarya All organisms that have a nucleus belong in this group. Protista – eukaryotic organisms that are not animals, plants, or fungi. This group is very diverse. Members of this group can be unicellular or multicellular. Some are photosynthetic and some are not. Fungi – These are all heterotrophs. Most eat dead or decaying organic matter. They secrete digestive enzymes into their food and then absorb the disgested food molecules. Examples of members of this group are mushrooms and yeast.

Plantae – This group has multicellular organisms that are photosynthetic autotrophs. They do not move. They have cell walls made of cellulose. This group has cone bearing plants as well as flowering plants and mosses and ferns. Animalia – these are all multicellular and heterotrophic. The cells do not have cell walls. Most animals can move. This is an extremely diverse group.