Topic #2 - Tree of Life Flashcards
Classification prior to DNA Sequencing
Primarily morphologically - Things that looked alike were related.
Phenetic or Phenotypic Classification
Classification using observable characteristics only.
Prokaryote vs. Eukaryotes
The first division of classification.
Prokaryotes
All are microbes. Nucleolus. No organelles. Circular chromosomes.
Eukaryotes
Some are microbes. Have organelles - endosymbionts.
Monera/Prokaryotae
All Prokaryotes
Protista
Whittaker - Small eukaryotes (many unicellular)
Fungi
Whittaker - Complex small eukaryotes - use ingestive nutrition
Classification with DNA Sequencing
Phyletic/Phylogenetic Approach - Gene Comparisons
Ribosomal RNA comparisons in DNA Sequencing
1st comparison: rRNA between 16S (in prokaryotes) & 18S (in eukaryotes).
Used b/c not many changes in rRNA so it’s easy to start here.
3 Domains
(Eu)Bacteria - Prokaryotes
Archaea(bacteria) - “Ancient” Prokaryotes
Eukarya - Eukaryotes
Archaea & Eukarya are closer than Arch & Bacteria
Binomial Nomenclature
Carroleus Linnaeus - Genus then Species. E. Coli - abbreviate when obvious
Cocci/Coccus
Round/Spherical
Strepto- (coccus)
Chain of cells
Diplo- (coccus)
Groupings of 2 cells
Staphylo- (coccus)
Packets of cells; bunches of grapes - don’t divide on same plane each time
Don’t Confuse Nomenclature & Biology
Streptococci in Streptococcus; not all in that genus doe. Be Careful.
Bacili/Baccilus
Rod-Shaped
Cocobacillus
Short, fat rods.
No fixed L:W ratio determining shape
Vibrio
Curved rod; Comma shape
Spirilla(-um)
Rigid spiral shape
Spirochete
Flexible spiral shape
Budding/Appendages
Stalks/Hypha
Filamentous
Long, thin cells
OR
Chains of cells (not streptococcus)
Pleiomorphic
Variable shape
Bacterial Size
Around 1-2 micrometers - variable but smaller than eukaryotes
Thiomargarita
A cell about 1mm long - can be seen by naked eye
Why So Small?
Higher SA:V ratio. More exchanged outside of cell
