Name: Date:

Classification: How Is Life Organized?Learning Outcomes:

1. Explain how the following principles are used in taxonomy to classify organisms:a) Evolutionary relationshipsb) Biochemical relationshipsc) Homologous structuresd) Embryological relationships

2. Compare characteristics of a prokaryotic cell with those of a eukaryotic cell.

3. Describe the unifying characteristics of the following Domains of life:a) Bacteriab) Archaeac) Eukarya

4. Classify organisms using the following taxons: Kingdom, phylum, sub-phylum, order, family, genus and species.

5. Apply binomial nomenclature to classify organisms.

Text: 308 to 314; 4; 6-7. *This is required reading!

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Cells as a Basis for ClassificationAt a very basic level, organisms can be divided based on whether they have cells or not. This will determine whether they are classified as “living” or “non-living”.

-Viruses are not considered to be non-living as they are not made up of a cell(s). Viruses are just protein capsules containing genetic material (RNA or DNA).

-Cells are only found in living organisms and they represent the lowest level of structure capable of performing all the activities required for life (e.g. Able to respond to their environment, metabolism)

Living organisms are divided into two large groups depending on what type of cell(s) they have. Name and describe the differences between the two:

a) Prokaryotic: -No membrane bound nucleus, just a nucleoid of a single long chromosome. -Only organelle is a ribosome (protein manufacture) b) Eukaryotic: -Membrane bound nucleus containing many chromosomes (46 in diploid human cells).-Many organelles.-Much larger in size.

Label the main structures highlighting the simularities and differences between these cell types.

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Phylogeny and the Tree of Life

Phylogenies Reflect Evolutionary HistoriesA phylogeny is the evolutionary history of a species or group of species.

What type of evidence can be used to discover a species phylogeny?a) Fossil Record: Documented evolutionary change that can be used to trace the phylogeny of many groups. Limited as not all organisms were fossilized, not all fossils available for study (destroyed via Earth processes, buried, etc).b) Morphological and molecular homologies: Reveal common ancestory and divergent evolution. Can be compared with analogous traits and convergent evolution.

Systematics Connects Classification with PhylogenySystematics is the branch of biology that classifies organisms and determines their evolutionary relationships. This is also called “taxonomy”

Systematics groups organisms into categories which range from very inclusive to very specific. Examine the diagram of a house cat’s classification:

a) Which category (taxon) is most inclusive?Domain, includes all organisms with eukaryotic cells.

b) Which taxon is least inclusive?Species, only includes house cats.

c) What do each taxon represent?Groups of individuals with shared traits and common ancestory.

d) What is represented by the scientific name Felis catus?-Species and genus.

e) What is any easy way to remember the correct order of the taxonomic categories?Dumb Kids Playing Chicken On Freeways Get Smashed

Phylogeny and classification are combined through the creation of a phylogenetic tree. Again, this is hierarchical and becomes more inclusive as you move through it.

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Phylogenetic TreesReconstructing a species’ evolutionary history involves sorting homologous from analogous features and then infering phylogeny. Below are the steps involved in this process:

1. Cladistics: -Common ancestry is used to group organisms into clades (ancestral species and its descendents, monophyletic).-Shared characteristic can be grouped two ways:

a) Shared ancestral characteristicOriginated in the common ancestor of a clade and is found in all members. The common ancestor is not a member of the clade! Example: Backbone in mammals (Found in the common ancestor of all vertebrates = are all related).

b) Shared derived characterUnique to a particular clade and did not appear in the common ancestor. Example: Hair in mammals (Hair is unique to mammals and as such separates them from the rest of the vertebrates on the phylogenetic tree below)Useful in distinguishing clades.

2. Creating Phylogenies Using Shared Characteristics-Shared characters can be organized into a Character Table that allows for a Phylogenetic Tree to be created.

Two clades are used in this process:

a) Outgroup: Species from a lineage known to have diverged before the species of interest. Example: Frog, represents common ancestorb) Ingroup: Group of species whose evolutionary relationships are being determined. Example: Iguana, Platypus, Kangaroo, Beaver.

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-Phylogenetic trees are organized based on the idea of parsimony, that the simplest explanation for observed phenomena are the best.

3. Molecular Systematics and Phylogenetic Trees-DNA and other molecular evidence can be used to trace phylogeny (remember the Molecular Connection assignment).

-DNA evidence is valuable as:

a) Can provide a timeline of evolution to support or refute the timeline created from fossil evidence.b) Provides evidence of similarity between organisms that no longer posses homologous traits.c) Useful where no fossil records exist.d) Can be used to look at short (mtDNA) or long (DNA) time periods.

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Constructing the Tree of LifeDomain is the largest classification taxa. What is evidence is used to determine to which domain organisms belong?Biochemical (“Molecular”): DNA and RNA.

Below is an image of our current understanding of the phylogeny of the three domains of life.

Next to each of the images below, name and briefly describe the domain it represents. Text: 6-7.

Domain Bacteria-Prokaryotes, unicellular, microscopic, contain ribosomes, DNA/RNA

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Domain Archaea-Prokaryotes, unicellular, microscopic, extremophiles, more similar to Eukaryotes than Bacteria.-Colony of many cells.

Domain Eukarya-Eukaryotes, uni/multi cellular, many organelles, organized nucleus, DNA and RNA (closely related to Archaea RNA), divided into 4 kingdoms.-See the video for an overview of the kingdoms: http://www.youtube.com/watch?v=BQ1JaYxBH40&feature=fvw

Take your own notes to explain how the kingdoms of the Domain Eukarya are divided:Kingdom Uni/Multi Cellular? Nutrition Other Info

Protista

Mainly uniA few multi algae

HeterotrophIf green = autotrophic (contain chloroplasts)

AquaticA catch all group

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Kingdom Uni/Multi Cellular? Nutrition Other Info

Fungi

Multi (except yeast) HeterotrophSaprotroph (decomposers)

Kingdom Uni/Multi Cellular? Nutrition Other Info

Plantae

Multi Autotrophic via photosynthesis in chloroplasts

A few parasitic

Cellulose in cell walls

Producers

Kingdom Uni/Multi Cellular? Nutrition Other Info

Animalia

Multi Heterotrophic No cell wall or chloroplasts

Motile

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