Binomial Nomenclature And The Future of

Classification

Know how the Linnaeus system should be used.

Describe how biochemistry can be used in classification.

Compare and Contrast the five kingdom and three-domain classification systems.

Binomial Nomenclature

• Use the first name from the Genus. This must have a capital first letter!

• Use the Species name as the second name. This must have a lower case first letter!

• Both words should be written in italics

Why Change?

• Original classification was based entirely on physiology that can be observed.

• By the seventeenth century microscopes had been developed to allow us to look at differences between single celled organisms, fungi and plants etc.

• Now electron microscopes help highlight specific differences that could not be observed earlier.

Aristotle’s Method

• All living things are either plants or animals.

• Animals can be divided into three groups:• Live and move in water.• Live and move on land.• Move through the air.

• What problems might this cause?• Where does man fit into this?

The Five Kingdom classification system

• Prokaryotes• No nucleus• Loop of naked DNA• No membrane bound organelles• Smaller ribosomes than other groups.• Respiration occurs in cytoplasm.• Small cells

The Five Kingdom classification system

• Protoctists• Eukaryotes• Mainly single celled (some multicellular)• Large variety of types• Plant or animal like features• Autotrophic or heterotrophic

The Five Kingdom classification system

• Fungi• Eukaryotes• Chitin based walls surround cytoplasm• Network of strands form body (mycelium) strands

are called Hyphae.• Multinucleate cytoplasm• saprophytic

The Five Kingdom classification system

• Plants• Eukaryotes• Multicellular• Cellulose cell wall surrounds the cell• Produce multicellular embryos from fertilised egg!• Autotrophic

The Five Kingdom classification system

• Animalia• Eukaryotes• Multicellular• Heterotrophic• Fertilised eggs develop into a ball of cells called a

blastula.• Often free moving.

Biochemistry

• Simple differences in the enzymes and biomolecules used by different organisms can show us how species have been related in the past.

• Cytochrome C is used in the respiration process. Nearly all organisms must respire, but many have different forms of Cyt-C.

• By looking at the amino acid structure we can identify how similar the Cyt-C is in between species. The more similar the Cyt-C, the more closely they are related!

Three Domain System

• Carl Woese based ideas on RNA studies in 1990 to develop a biochemical method of classification.

• He divided the prokaryote kingdom in two (Eubacteria and Archaebacteria).

• He had another domain called Eukaryote.• This system also made use of structural

differences, but relied on bichemistry as well.

What do Eubacteria have that Archaebacteria Do Not?

• Different cell membrane structure.

• Flagella with different internal structures.

• Different enzymes (RNA polymerase) for building RNA

• No protein bound to their genetic material.

• Different mechanism for DNA replication and building RNA.

Archaebacteria Have Similarities With Eukaryotae!

• Similar enzymes (RNA polymerase) for building RNA.

• Similar mechanisms for DNA replication and building RNA.

• Productions of some proteins that bind to their DNA.

Questions

• What is the main difference between the two classification systems?

• Will this have an effect on the Linnaeus method of naming new organisms?

• Which is the most specific way to group and classify species?

• Which do you think should be used and why?