Classification

Cell Types Cells come in all types of shapes and sizes. Cell Membrane – cells are surrounded by a thin flexible layer Also known as a plasma membrane Eukaryotes – are cells that enclose their DNA in nuclei Prokaryotes – are cells that do not enclose DNA in nuclei

Cell Types Eukaryotic cells have the ability to specialize Have a specific function in a multicellular organism This gives rise to multicellular and more complex organisms

Cell Types Prokaryotic cells do not have the ability to specialize This limits their ability to form multicellular organisms Prokaryotes also need to rely on outside sources to feed Eukaryotes have the ability to in some cases manufacture food. Eukaryotes have the ability to break down larger molecules for food

Taxonomy and Evolution Taxonomy Taxonomy – (a branch of Biology) involves the identification, naming, and classification of species To reduce confusion in discussing organisms One goal of taxonomy is to assign a universal scientific name to each known species Systemics – the science of naming things Taxon – the groups that systematics organize living organisms in

Domains Larger, more inclusive category than a kingdom Domains: Bacteria (corresponds to the kingdom Eubacteria) Archaea (corresponds to the kingdom Archaebacteria) Eukarya (corresponds to the kingdoms Fungi, Plantae, Animalia, and Protista)

Six Kingdom Scheme Eubacteria Archaebacteria Protist Fungi Plantae Animalia

The Linnaean System of Classification Developed by botanist Carolus Linnaeus ( )

The Linnaean System of Classification Groups of similar (genera – plural of genus) in the same family Families placed in orders Orders into Classes Classes into Phyla Phyla are grouped into Kingdom

Binomial Nomenclature Each species is assigned a two part scientific name Scientific names are written in italic First word begins with a capital letter Genus Second word is lowercase Species (can interbreed and form fertile offspring)

Modern Evolutionary Classification Phylogeny – the evolutionary history of lineages The goal of phylogenetic systematics, or evolutionary classification, is to group species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences

Molecular Data as a Taxonomic Tool Relatedness is measured by comparing genes and gene products (proteins) The more sequences match, the closer they are related. Molecular data is independent of structural data Structural is a traditional method Accuracy will depend on molecular data supported by structural data Fossil data supports: Whales are closely related to Hippos, pigs, camels…. Supported by molecular data

Phylogenetic Trees DNA began a new era in Taxonomy in the 1960’s Along with computers The pattern of branches can tell you how closely related species are The deeper the “split” the further “away” the two species are from each other The closer the “split” the more related

Phylogenetic Trees Clade Clade – each evolutionary branch in a polygenetic tree A group of species that include a single common ancestor Clades can nest within larger clades Each item in a clade may be an individual species genus, a family or other taxonomic group

Cladistics Method mostly used today Key rule: all organisms of a clade share homologous structures that do not occur outside the clade Derived Characters Derived Characters – unique features that unite the organisms as a clade Cladogram Cladogram – links groups of organisms by showing how evolutionary lines, or lineages, branched off from common ancestors.

Cladistics Monophyletic Group – includes a single common ancestor and all its descendants

Building A Cladogram Refer to page 517 Speciation event – when one ancestral species splits into 2 new ones. This is the basis of each branch point or node The node represents the last point which the 2 lineages shared a common ancestor The bottom or “root” of a cladogram represents the common ancestor shared by all of the organisms in the cladogram

Building A Cladogram A cladogram’s patterns degrees of relatedness among organisms

Building A Cladogram Derived Character – A trait that arose in the most recent common ancestor of a particular lineage and was passed along to their decedents.

In your Composition Book Quick Lab Page 520 Answer all questions

DNA in Classification All organisms carry genetic information in their DNA Passed on from earlier generations Many different organisms share many genes and show important homologies that can be used to determine evolutionary relationships Using DNA has made evolution more accurate

Molecular Clock Method used by researchers that uses mutation rates in DNA to estimate the length of time that 2 species have been evolving independently