- Slides: 24
Notes: Classification of Living Things n For more than 3. 5 billion years, life on Earth has been constantly changing. Natural selection and other processes have lead to a staggering diversity of organisms. Biologists have identified and named about 1. 5 million different organisms so far (with many more that have yet to be discovered)
How do we define what is alive? Living things share the following characteristics of life… n All living things: n Made of Cells n Reproduce n Based on a universal genetic code (DNA) n Grow and develop n Obtain and use energy n Respond to environment n Maintain homeostasis n Change over time
n Today, we classify all living organisms based upon a system that was developed over 200 years ago by a Swedish botanist named Carolus Linnaeus.
n Linnaeus created a system of naming all living things called binomial nomenclature. – According to this system, each organism should be given a two-word name, called a scientific name.
n The same name is used regardless of the language that a person speaks or the region they live in. – This also helps avoid the problems with common names that may change based upon the region that individuals live in (i. e. mountain lion, cougar and Florida panther are all the same species found in various places in the US)
n Most names are in Latin (so they sound different than our words) – The first word of each name is called the genus. The first letter of this name should always be capitalized. – The second word of each name is the species identifier. This name should always be in lower case. Ex. The scientific name for humans is Homo sapiens (Genus + species) …. notice it is written in italic print n
n Similar organisms that may be the same genus but not the same species can sometimes reproduce under artificial conditions. However, their offspring often end up being sterile. Two examples of interbreeding two different species are…
. . add this to your notes! n Species: A group of organisms that can successfully interbreed to produce offspring that can also interbreed. n i. e: they can produce children that can continue to produce children.
Horse Donkey +
Mule n Mule x Mule= no offspring
Lion Tiger Lion + Tiger
Linnaeus’ original classification system was made up of 7 levels called Taxa: Complete the following table as we go through the notes.
Linnaeus’s taxa (largest to smallest) Bobcat Classification Lynx Classification Kingdom Phylum Class Order Family Genus Species Animalia Chordata Mammalia Carnivora Felidae Lynx rufus Animalia Chordata Mammalia Carnivora Felidae Lynx candensis
Words to Know: Taxon: a single taxonomic group. Taxa: more than one taxonomic group. Taxonomy: study of classifying living things Taxonomist: scientist who studies classification
n What is the scientific name for the Lynx? – Lynx candensis
n Which is more closely related to the lynx, the Leopard (Panthera pardus) or the Bobcat (Lynx rufus)? Leopard Bobcat
n The Bobcat because they are in the same genus. Lynx Bobcat
n In the original classification system it was thought that all living organisms could be grouped into one of the two kingdoms: – The Plant Kingdom or the Animal Kingdom – Why might it have been necessary to create more than two kingdoms? n Not everything can be grouped into those two kingdoms.
Table 1: Changing Number of Kingdoms Plantae Original Division (written in latin) 19501990 TODAY Monera (all bacteria) Eubacteria Arachaebacteria Animalia Protista Fungi Plantae Animalia
n Domain- a new level that (is larger than a kingdom) has been added to the current classification system. Based on new research, all iving things in the six kingdoms were placed into one of the 3 Domains:
n n n Domain Bacteria- includes all of kingdom Eubacteria (also known as ‘true bacteria’) Domain Archaea- includes all of kingdom Arachaebacteria (also known as ‘ancient bacteria’) Domain Eukarya- includes the kingdoms Protista, Fungi, Plantae and Anamalia (all of which are eukaryotes)
Fill in the correct taxa for the new (current) structure of the classification system: Species Genus Family Order Class Phylum Kingdom Domain