Transcript Ch. 18 : Classification of Living Organisms

Ch. 18 : Classification
of Living Organisms
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Millions of organisms
Only thousands named and studied
Grouping makes its easier to study
TAXONOMY = the branch of biology
that names and groups organisms
according to their characteristics and
evolutionary history.
taxonomy
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Aristotle ; plants or animals, animals where either
land-dwellers, water-dwellers or air-dwellers.
Carolus Linnaeus ; Swedish naturalist, mid 1770’s,
realized that every area had their own
name/language for organisms. Converted
everything to latin so that names were universal.
Linnaeus’s system used morphology( form and
structure) to classify organisms.
Today we are reclassifying some organisms based
on their DNA sequences.
Levels of classification
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Domain – largest level of classification based on cell type (eukaryotic
and prokaryotic)
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Kingdom – big groups based on cell type, cell number, nutrition and
reproduction
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There are
orders of birds
Family – still smaller and more similar
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animal kingdom is divided into vertebrates and invertebrates
Class – smaller groups
Order – more similar
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Animalia, Plantae, Protista, Fungi, and Bacterias
Phylum – kingdoms are subdivided
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Eukarya, Eubacteria and Archeobacter
You are familiar with families like feline, canine, equine, bovine, etc
Genus – like a last name
Species – very specific, each organism belongs to its own species
Levels of classification
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Domain Kingdom - Animalia
Phylum - chordata
Class - mammalia
Order - carnivora
Family – felidae
Genus - Panthera
Species – P. leo
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Scientific name = Panthera leo
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terms
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Phylogeny: using evidence and hypotheses to
evaluate morphology and that of ancestral
organisms (related because of structures and
shapes)
Systemics: organizing the diverse life forms
around their evolutionary tree (thing of
‘branching or branches’)
Morpholgy: shape or form
Cladistics: uses features to determine
common ancestors ( feathers – bird family)
6 Kingdom System
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Archaebacteria* – prokaryotic cell
Eubacteria – prokaryotic cell
Protista – 1 , eukaryotic cell
Fungi – 1 to many, eukaryotic cells
Plantae – many eukaryotic cells
Animalia – many eukaryotic cells
* You will see variety of spellings
Types of cells
* see Ch. 1 notes for a detailed table
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Prokaryotic
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Prokaryotes have prokaryotic cells which have a
cell membrane, cytoplasm with ribosomes and
DNA in the form of 1 chromosome – there is NO
nuclear membrane and no membrane bound
organelles.
Eukaryotic
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Eukaryotes have eukaryotic cells which have a cell
membrane, cytoplasm full of membrane bound
organelles and many chromosomes that are
contained in a nucleus surrounded by a nuclear
membrane.
Prokaryotic (bacteria) and
eukaryotic cells (animal)
Domain
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Relatively new in the classification
system is the idea of domain. There are
three domains
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Archae
Prokaryae
eukarya
Archaebacteria
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Unicellular
Prokaryotes
Unique DNA
Ancient
chemotrophic
Harsh environments, often without O2
reproduce using binary fission
Eubacteria
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Unicellular
Prokaryotes
“true”
Binary fission
Many modes of nutrition
May move with flagella or be spirochetes
Unique cells walls that are either Gram
positive or Gram negative depending on ratio
of starch to lipid
Protista
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Eukaryotic cells
Single celled organisms
‘don’t fit elsewhere’
Lots of variety
Algae (plant like)
Zooplankton (animal like)
Variety of cell walls – sometimes pellicle and
sometimes silica
Various modes of reproduction
Fungi
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Single celled (yeast) and multi-celled
(mushrooms)
Eukaryotic cells
Heterotrophic – even the
green ones eat – they are
not photosynthetic
Absorptive nutrition- digest food outside
Plantae
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Multicellular organisms
eukaryotic
Cell walls of cellulose
Photosynthetic – have chlorophyll
Cells are organized into tissues called
roots, stems and leaves with specialized
functions.
Reproduce sexually and asexually
Animalia
Heterotrophic ( eat )
 Multicellular
 eukaryotic
 Sexual reproduction
(a few have limited regeneration capabilities)
 Respond with movement and
 have muscle and nervous tissue
 Never have cell walls
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