Classification

  1. Taxonomy

Taxonomy is also known as systemic biology.

It is the study of classification of living things.

  1. Early Classification

2000 years ago, Aristotle classified organisms as plant or animal.

Those names were too long and a long series of descriptive terms.

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
  1. Carolus Linnaeus (real name was Carl von Linne)

Father of modern Taxonomy

He developed two Kingdom system – Plantae and Animalia

He grouped organisms according to shared characteristics.

The group was called a Taxon (plural is Taxa).

He used Latin to name the taxa.

  1. Modern System

Uses Binomial Nomenclature system to name organisms

Uses Latinized names

Genus and species names always written together

Ex Homo sapien or Homo sapien,, Canis lupus or Canis lupus

Species – organisms that can interbreed and produce fertile offspring.

Genus – group of closely related species

V.Three Domain System

Domain Archaea (Kingdom Archaebacteria)

Domain Bacteria (Kingdom Eubacteria)

Domain Eukarya (protists, fungi, plants and animals)

  1. Six Kingdom System
  1. Kingdom Archeabacteria
  2. includes bacteria- like organisms that live in extreme conditions, such as very hot, very cold or very salty (extremophiles)
  3. unicellular, prokaryotic - they have no nucleus
  4. mostly anaerobic – they don’t use oxygen
  5. chemosynthetic – uses inorganic substances as an energy source
  6. cell membranes contain unusual lipids
  7. cell walls lack peptidoglycan

2.Kingdom Eubacteria

  • Unicellular, prokaryotes
  • includes bacteria
  • most are heterotrophic - cannot produce their own food
  • also includes blue green algae, which are also called cyanobacteria and can produce their own food (autotrophic)
  • cells have thick, rigid cell walls, containing peptidoglycan
  • live in very diverse ecological environments
  1. Protista
  2. includes unicellular and multicellular organisms
  3. great variety of organisms within the kingdom
  4. includes Paramecium, Amoebas, protozoans are heterotrophic.
  5. The brown, yellow, red and green algae are autotrophic and use photosynthesis to produce their own food.
  1. Fungi
  2. Cell wall made of Chitin.
  3. Most are eukaryotic. Yeasts are unicellular.
  4. The mushrooms, molds and mildew are multicellular, heterotrophic and decomposers.
  1. Plantae
  2. They are eukaryotic, multicellular and autotrophic (photosynthetic).
  3. This kingdom includes the mosses, ferns, shrubs, grasses, trees and flowers.
  1. Animalia
  2. They are eukaryotic, multicellular and cannot produce their own food (heterotrophic).
  3. There are both invertebrates (no backbone) and vertebrates (with a backbone).

VII.Basis for Classification

  1. Structural similarities (main basis)
  2. Chromosome structure (DNA)
  3. Biochemical similarities
  4. Embryological development
  5. Reproductive potential
  6. Evolutionary history
  1. Uses cladistic analysis
  2. Clade- group of ancestral species & all its descendants
  3. Cladograms
  1. shows evolutionary relationships among a group of organisms.
  2. ancestors at node, length of branch = evolutionary time (extinct group short branch)
  3. sister taxa – have common ancestor, and one taxa is not evolved from the other
  4. uses derived characteristics (derived/inherited from a common ancestor means acquired traits) - traits that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants.
  5. helps scientists understand how one lineage branched from another during evolution
  1. Molecular Clocks
  2. Uses DNA comparisons to estimate length of time that two species have been evolving separately .
  3. More similar the DNAMore recently they shared a common ancestorMore Closely related they are in evolutionary terms
  4. Measures neutralmutations that have no effect on how an organism looks (phenotype).
  5. These mutations accumulate in the DNA of different species at about the same rate.
  6. 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.
  7. Molecular clocks allow researchers to time different kinds of evolutionary events.
  1. Earth’s early History

Earth is about 4.6 billion years old. Earth's early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water.

Earth’s early atmosphere contained little or no oxygen.Cyanobacteria, single-celled prokaryotic organisms must have evolved in the absence of oxygen. They produced oxygen, as an end product of photosynthesis.

Hence concentrations of methane and hydrogen sulfide began to decrease, the ozone layer began to form.

The First Organic Molecules:

IX. Koch's Postulates - Germ Theory

Robert Koch applied the principles to establish the bacterial cause of tuberculosis and anthrax.

A plan of experimentation necessary to prove that a disease is caused by a specific infectious agent and to isolate/identify the infectious agent.