BIO 115 Lecture Notes - Lecture 7: Microorganism, Plasmid, Chloroplast
7. Microbial Diversity
Classification & Phylogenies
oSynapomorphy & Symplesiomorphy
Unique to specific group
oMonophyletic group
Shared common ancestor and all descendents
oParaphyletic group
Common ancestor and some descendents
oProkaryotes
Bacteria & archaea
No nuclear envelope
Specialists not simple
Metabolic processes are extremely diverse and complicated
Outnumber eukaryotes
Movement by diffusion
Found in extreme environments
No common set ➝ does not mean no organelles
oEukaryotes
Animals, plants, fungi, protozoans
Movement by endomembrane system
Common set of organelles
oWhy do we need a system?
Organization
Communication
Different languages
oPhylogeny
Classification based on evolutionary history
oCarl Woese
Proposed using rRNA gene as molecular tool
Led to discovery of the domain Archaea
orRNA genes
Every cell has them
There are regions that are highly conserved
There are regions that are variable
Great for initial ID
Not good for detailed info
Archaea
oAt molecular level, archaeal proteins for DNA processes are more similar to euk,
than bacteria
oCell Membrane Lipids
Polar head groups more diverse in Archaea
oArchaea are everywhere, not just extreme environments
Cell Wall Structure
oBacteria
Membrane, wall, membrane
find more resources at oneclass.com
find more resources at oneclass.com
Have a cell wall
Composed of peptidoglycan
Structure determines how a cell responds to the gram stain/ how thick
Some have S layer (most external part)
Gram negative have outer membrane
oArchaea
Mant don’t have a cell wall
Components diverse
No outer membrane
oWhy don't we know more?
Hard to culture
All archaea are extremophiles
Gram Staining
o1884: Hans Christian Gram
oNot phylogenetically helpful but clinically important
Specialized cells & cell structures
oSwarmers & Stalks
(chill & dont swim)
Glue that holds stalked cell is one of nature's most strongest materials
oEndospores
Extremely resistant to environmental damages
Response to an environment traits struggling/ in decline
oAkinetes
Cyanobacteria
Dormant & photosynthetic
Thick cell wall
Filled with food reserves
If it pulls apart it doesn’t die
oHeterocysts
Produced by some cyanobacteria that can fix nitrogen
Take N2 into form to make amino acid and others
Cyanobacteria can make N itself ➝ Nitrogen fixation is done itself
Anaerobic cell (free of oxygen)
oAnammoxosome
Specialized organelle
Microbiomes
oComplex interactions
Termites
Can't digest cellulose
Protists
Break wood particles into smaller pieces
Bacteria
Secrete digestive enzymes that break down cellulose
Archaea
Methanogens- minimal nutrient required
oHuman Microbiome Project
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Classification & phylogenies: synapomorphy & symplesiomorphy. Unique to specific group: monophyletic group. Shared common ancestor and all descendents: paraphyletic group. Common ancestor and some descendents: prokaryotes. Metabolic processes are extremely diverse and complicated. No common set does not mean no organelles: eukaryotes. Classification based on evolutionary history: carl woese. Led to discovery of the domain archaea o rrna genes. There are regions that are highly conserved. Archaea: at molecular level, archaeal proteins for dna processes are more similar to euk, than bacteria, cell membrane lipids. Polar head groups more diverse in archaea: archaea are everywhere, not just extreme environments. Structure determines how a cell responds to the gram stain/ how thick. Gram negative have outer membrane: archaea. 1884: hans christian gram: not phylogenetically helpful but clinically important. Specialized cells & cell structures: swarmers & stalks (chill & dont swim) Glue that holds stalked cell is one of nature"s most strongest materials: endospores.
