The Classification of Living Organisms Copyright 2010. PEER.tamu.edu

Why classify things? Say you go to the mall to get some new clothes. Where would you go? How would you know to go to that particular store?

How is a mall organized? Food Court Big Department Stores Specialty Clothing Stores Jewelry Stores Electronics Stores Shoe Stores Toy Stores Kiosks

Can you imagine if the mall was just one big store and you had to go through rows and rows of “stuff” to find the right clothes in the right brand and the right size for you? How long would that take?

Big Idea: The mall, your city, your school, and your closet (hopefully) are all organized so that you and other people can get things done without wasting extra time and effort. Scientists also organize or classify things so that they are easier to investigate and understand.

Classification Activity FOOTWEAR! Brainstorm 2 initial categories into which all footwear fall Look at your shoes and place yourselves in one of the two groups Write in flow-chart form below first two categories the second two. 1. (ie. boot/shoe; leather/cloth; heel/no heel; laces/no laces) 2. Write categories on board: one on left side at top, one on right side at top

Brainstorm 2 more categories into which all footwear from your group divides

One more time! (there should now be 8 distinct groups) Come up with a name for your species of footwear

Activity Wrap-Up What difficulties did you have in coming up with categories or in determining which group you belonged to? How might this apply to classification systems used by scientists in the field? 1. Ambiguities? (Shades of colour, different sizes, etc.)

Here are some things that scientists classify or organize: The elements The human body Interactions in Ecosystems

Scientists also Classify Living Organisms Cats, dogs, mammals, pets, friends……… How could you classify these living things?

Quick, organize these living things into groups:

Are there any other ways to group these living things? Did you do it like this? These are grouped by type of organisms: Fish, butterfly or bird This is probably a more meaningful way to group these for scientific purposes than the previous slide’s grouping by color. Are there any other ways to group these living things?

Or this? These are grouped by color: Blue, red or red and blue

Physical characteristics Species Concepts Morphological Species Concept: Species compared based on Body shape Size Structural features Physical characteristics

Species Concepts Biological Species Concept: Fertile Offspring Species determined based on Similar characteristics Ability to interbreed in natural circumstances and produce viable offspring Fertile Offspring

Evolutionary relationships Species Concepts Phylogenic Species Concept: Species compared based on Evolutionary history Relationships among organisms based on DNA analysis Evolutionary relationships

Classification: Text p. 13, Activity 1.1: Snake or Lizard -silent independent reading/brainstorming 4 mins -share thoughts with partner 2 mins What makes this type of classification `Morphological`?

The most basic classification system is based on Domains and Kingdoms The most basic classification system is based on Domains and Kingdoms. Basic Classification Domains: Archaea There are three Domains of living organisms based on their characteristics: Archaea (also called Archaebacteria) Eubacteria (also called Bacteria) Eukaryota (also called Eukarya) Eubacteria Eukaryota The archaebacteria generally grow in extreme environments and have unusual lipids in their cell membranes and distinctive RNA molecules in their cytoplasm. Eubacteria (True bacteria) The presence of a nucleus gives eukaryotes their name, which comes from the Greek ευ (eu, "good") andκάρυον (karyon, "nut" or "kernel"). Most eukaryotic cells also contain other membrane-bound organelles such as mitochondria,chloroplasts and the Golgi apparatus. All large complex organisms are eukaryotes, including animals, plants and fungi. The group also includes many unicellular organisms. Cell division in eukaryotes is different from that in organisms without a nucleus (Prokaryote). It involves separating the duplicatedchromosomes, through movements directed by microtubules. There are two types of division processes. In mitosis, one cell divides to produce two genetically identical cells. In meiosis, which is required in sexual reproduction, one diploid cell (having two instances of each chromosome, one from each parent) undergoes recombination of each pair of parental chromosomes, and then two stages of cell division, resulting in four haploid cells (gametes). Each gamete has just one complement of chromosomes, each a unique mix of the corresponding pair of parental chromosomes.

Organisms are classified into Domains or Kingdoms based on these characteristics: 1. Whether they are unicellular or multicellular 2. Whether they are prokaryotic or eukaryotic 3. Whether they have a cell wall or cell membrane 4. Whether they have membrane bound organelles 5. Whether they are autotrophic or heterotrophic 6. Whether they reproduce sexually or asexually 7. How they tolerate heat, salt, or other extreme conditions See Vocabulary Activity in this Module.

Basic Classification Kingdoms: The Domains can also be split into Kingdoms which further divide the organisms by their characteristics. K I N G D O M S D O M A I N S

Kingdoms

“Archaea” means “ancient” bacteria. Organisms in Archaea are: Domain Archaea Aerial view of hot spring at Yellowstone “Archaea” means “ancient” bacteria. Organisms in Archaea are: Unicellular Prokaryotic Autotrophic or heterotrophic Organisms that reproduce asexually Bacteria that have adapted to extreme environments. Some can survive in extremely hot environments, like around hot springs and geysers. They are called thermophiles. Some can survive in extremely salty environments, like The Great Salt Lake in Utah. They are called halophiles. The Domain Archaea has one Kingdom, also called Archaea

This hot spring is flowing into the Firehole River in Yellowstone This hot spring is flowing into the Firehole River in Yellowstone. The colors are caused by different varieties of archaebacteria and other microscopic life forms. Scientists can distinguish temperatures of water by the colors present.

Domain Eubacteria “Eu” means “true” bacteria. They are: Unicellular Prokaryotic Autotrophic or heterotrophic Organisms that reproduce asexually The most abundant organisms on earth. One bacterium can give rise to 10 million in 24 hours. Found in almost every habitat on earth. The Domain Eubacteria has one Kingdom, also called Eubacteria. Many are common infectious agents.

This is a picture of bacteria on the skin This is a picture of bacteria on the skin. Bacteria can be shaped like a sphere (cocci) like this picture, like a rod, or like a spiral. The structure in the middle of this picture is a hair follicle with a hair growing out of it.

Nucleus and Organelles Terminology: The Domains Archaea and Eubacteria are commonly grouped together in discussion and called prokaryotes because they lack membrane-bound nuclei and membrane-bound organelles. Nucleus and Organelles

Domain Eukaryota (Eukarya) Eukaryotic Very diverse Unicellular or multicellular Autotrophic or heterotrophic Reproduce sexually or asexually Can be split into 4 Kingdoms- Protista Fungi Plantae Animalia The defining membrane-bound structure that differentiates eukaryotic cells from prokaryotic cells is the cell nucleus, within which the genetic material and many other cell bodies are contained. The presence of a nucleus gives eukaryotes their name that derives from the Greek (eu, "good") and (karyon, "kernel"). 

The 4 Kingdoms in Eukaryota Protista Mostly unicellular and microscopic Autotrophic or heterotrophic Can be infectious agents Examples: Amoeba Algae Daphnia Plasmodium (causes malaria) Plantae Multicellular green plants Autotrophic through photosynthesis Have a cell wall Mosses Ferns Trees Flowering Plants Fungi Multicellular Heterotrophic Decomposers Mushrooms Athlete’s foot Bread Mold Animalia Multicellular Animals No Cell Wall Insects Spiders Crabs Birds Humans

D O M A I N S K I N G D O M S

Taxonomic Classification: the answer to confusion Binomial nomenclature: Binomial = 2 parts Nomenclature = naming system Species name composed of: 1: Genus name 2: Species name Eg. Homo sapiens (or Homo sapiens if handwritten) -Look at p. 15 in text

How would you classify these? A organism that can exist in extremely hot temperatures and that is made of only one cell with no nucleus Domain: Archaea Kingdom: Archaea A green organism growing from the ground that is multicellular and that undergoes photosynthesis; its cells have nuclei and cell walls Domain: Eukaryota Kingdom: Plantae

Try two more: This microscopic and one-celled organism lives in colonies with millions of others like it. It does not have a nucleus and cannot survive in extreme conditions. It could be an infectious agent. Domain: Eubacteria Kingdom: Eubacteria This organism is a multicellular decomposer; its cells have nuclei. Domain: Eukaryota Kingdom: Fungi

Classification Systems Can Change! Can you guess why? Classification systems change as new organisms are discovered and as more information is gained about known living organisms. Science is a “work in progress” and things change as new evidence is found. There is a great amount of debate over the current classification system, especially the classification of the types of bacteria and whether viruses are alive or not.

Homework! Review pp. 8-23 in your textbook and answer 1.1 even questions 1.2, questions 1, 3, 5 Define: unicellular & multicellular prokaryotic & eukaryotic autotrophic & heterotrophic sexual & asexual

Veterinarians classify organisms for many reasons: Veterinarians have to classify infectious organisms so that they can understand how to treat them, according to their characteristics. It is important to know if they are bacteria, protozoa, prions, or viruses. Veterinarians have to classify their patients so that they can understand how their patients’ body systems work and how to treat those systems. Different species, and even different breeds, react differently to treatment. See Infectious Disease Lesson in this Module.

Which one would you choose? Why? Even though classification is not an exact science, it is a part of almost every aspect of our lives. This is an example of classifying by personal preference which all students have experience with. Which one would you choose? Why?