CHAPTERS 18 AND 19 Classification and the Tree of Life
Feb 20, 2016
CHAPTERS 18 AND 19
Classification and the Tree of Life
SYSTEMATICS The scientific way of organizing and
naming living things Dichotomous keys are used for
identification purposesBased on physical traits
CLADOGRAMSCladograms are diagrams the depict the pattern of shared characters, either derived characters or primitive charactersPrimative: characteristic shared by all organisms in the cladogram (Vert. ColumnDerived: trait that arose in the most recent common ancestorBased on DNA, skeletal, and comparisons
CLADOGRAMS Clade: Consists of a single
common ancestor and all the groups that descended from that ancestor Organism A,B,C are all
related because they are in the same Clade
Organisms B and C are more closely related than B and A because organisms B and C share a common trait
Node: Point where two groups branch off from each other
CLADOGRAM
1. Which traits does a lizard and a salamander share?2. Which two organisms are most closely related?3. What trait does a human have that gorilla does not?
PHYLOGENY & SYSTEMATICSCarolus Linnaeus first to assign each species a two-part latinized name called binomial nomenclature (Genus species)Ex: Homo sapians
PHYLOGENY & SYSTEMATICS
Phylogenetic trees show the relationship between classification and phylogenyYear 2525 Activity
OLD WAY 5 Kingdoms – Bacteria grouped into one kingdom called Monera
NEW WAY 6 Kingdoms1. Eubacteria*2. Achaebacteria*3. Plantae4. Animalia5. Fungi6. Protista
3 Domains: Bacteria, Achaea, and Eukarya (Plantae, Animalia, Fungi, and Protista)
BACTERIA VS. ARCHAEA The first two of the 3 domain system Kingdom Bacteria (Eubacteria) Kingdom Archaeabacteria Both are unicellular and
prokaryotic
BACTERIA Bacteria are classified by
shape: Spheres are cocci –us Rods are bacilli –us Curves or spirals are spirilli
-um
EUBACTERIA• Free living or parasitic• Unicellular• As a group they exhibit
much more nutrition diversity than eukaryotes, ex: cyanobacteria
ARCHAEABACTERIA• They are the oldest life-
forms & remain the most numerous & widespread organisms
• Unicellular or multicellular
• Archaea are extremeophiles• Halophiles – salt loving• Thermophiles – hot vents• Methanogens – gassy
areas
REPRODUCTION Reproduce via binary fission or conjugation Binary Fission = form of asexual reproduction Conjugation = Transfer of genetic material by
cell to cell contact
BACTERIA
BACTERIA External Structures: Capsule - the cell wall is
covered in a sticky capsule, this slime layer helps to evade the immune system & adhere to surfaces
BACTERIA External Structures: Pili - used to stick to
their substrate, hair-like projections, & can be used for the exchange of genetic material (sex pili)
BACTERIA• External Structures:• Flagella - enable bacteria
to move, embedded in the cell membrane & cell wall
• Other forms of motility include chemotaxis, phototaxis & magnetotaxis
BACTERIA• Internal Structures:• Endospores - some
prokaryotes can withstand harsh conditions by remaining dormant, until conditions become favorable; just encloses the DNA
BACTERIA Some bacteria cause
disease, called pathogenic bacteria
They can release exotoxins or endotoxins
BACTERIA Bacteria can be used
as biological weapons Ex: anthrax
BACTERIA
• Prokaryotes help recycle chemicals, dead and decaying materials and they can help clean the environment
• Examples of bioremediation: sewage treatment facilities, oil spills & toxic mine wastes
VIRUSES Non-living particles composed of two main
parts: Nucleic Acids (DNA or RNA) Protein Coat (capsid) No membranes, cytoplasm, ribosomes or
other organelles They cannot move or grow, and can only
reproduce inside a host cell (No Kingdom affiliation)
Extremely small and only visible with advanced electron microscopes
VIRUSES Human Examples: Chickenpox Smallpox Rabies AIDS Cancers Hepatitis Influenza A, B & C
BACTERIOPHAGES Bacteriophage Virus that infects bacterial
cells Structure: Head (Capsid),
DNA, Tail & Tail Fibers
LIFE CYCLE OF A VIRUSLYTIC CYCLE LYSOGENIC CYCLE
DNA or RNA injected into host
Replication, transcription, and translation occurs
Cell bursts and new bacteriophages emerge
**Kills host cell**
DNA or RNA injected into host
Prophage is made = cell DNA + bacterial DNA
Virus can be released or remain within host cell
**Coexists within host cell**