TAXONOMY

But first… Evolution retest (Wednesday or Thursday this week @ lunch) - OPTION’s INCLUDE Rewriting the whole test Rewriting the 15mk Hardy-Weinberg question (with better wording…) Not required to come see me for lunch time tutorial, or show test corrections…

However… Your retest mark will be your test mark… I am happy to make myself available for any extra help during lunch hour for anyone who is interested, and wants to boost their grade!

Outlook for the week Today: -Taxonomy and Dichotomous keys Break - Intro to Viruses Wednesday: - Microscopy and Scientific Drawings

What is Taxonomy Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. But why group organisms??

Try this: Quickly write out a grocery list E.g. Milk Eggs Apples Chicken Beef Carrots Spinach Grapes

What items on your list are similar? Are those items typically found in the same area of your grocery store? How difficult would shopping be if these items were not grouped together? And that is why scientists classify organisms into groups using Taxonomic systems

Taxonomy Greek philosopher, Aristotle, began classifying living things as either plants or animals Animals were subdivided into land dwellers, water dwellers, air dwellers Plants classified based on stem types As science advanced, and new species were being discovered there were problems with Aristotle’s system Common names varied from place to place Common names were not great descriptors of animals (e.g. Jellyfish… are not fish at all)

Linnaeus System of Classification Swedish Naturalist, devised a hierarchical system for grouping organisms… mostly based on morphology (structure, form)

N.B. Animals go by “phylum”, Plants go by the subset “domain”

Six Kingdoms Kingdom Archaebacteria – e.g. extremophile bacteria Kingdom Eubacteria – e.g. Escherichia coli Kingdom Protista – e.g. Amoebas Kingdom Fungi – e.g. Agaricus bisporus (store mushroom) Kingdom Plantae – e.g. Orchid Kingdom Animalia – e.g. Homo sapiens

Naming organisms Under Linneaus system, organisms were given scientific names First part of name is genus, second part is the species identifier. This is what is known as binomial nomenclature What are some scientific names we recognize?

Naming organisms (cont’d) By custom, the Genus name is capitalized, species name is lower case. When hand writing, ALWAYS underline scientific names. When typing always italicize. E.g. Homo sapiens or Homo sapiens

Quick Check What subset of the Linneaus system would have more species in it: the Class or the Phyla?

The Three Domain System (fig 18.11) Recent advances in molecular biology has lead to an alternative to the 6 kingdom system By studying our old friend rRNA (found in all living organisms), scientists are able to classify all living things into three distinct domains: Domain Bacteria (Eubacteria [Prokaryotic]) Domain Archae (Archaebacteria [Prokaryotic]) Domain Eukarya (Cells with true nucleus [Eukaryotic])

Remember the pneumonic: Did King Phillip Come Over For Grape Soda Remember the pneumonic: Did King Phillip Come Over For Grape Soda? Domain Kingdom Phylum Class Order Family Genus Species

Dichotomous Keys An tool used by scientists to identify items in the natural world, and consist of a series of choices which lead to the identification.

Let’s Make a Dichotomous Key! First, I need 10 volunteers to donate a shoe for the activity. In groups (3-4ppl) make a table to describe each shoe using these headings: Left/Right, Men’s/Women’s, Laced/Slip on, Color, size, owner.

Dichotomous Key (DK) Once you have finished your chart, make 2 dichotomous keys (1 flow-chart, 1 question-directional) (Use p354/355 in text for guidance) When you have finished your DK, exchange DK’s with another group, and see if you can figure out who’s shoe is who’s using their DK. (Provide CONSTRUCTIVE feedback if necessary)

When finished…