L7: Breaking down Taxonomy Flashcards
NO
Breaking down the old way of taxonomy (4 steps)
traditionally very dichotomous (plants vs animals)
The Heckel introduced 3 kingdoms (animal, plant, and protist) with the Tree of life
Copeland added in Monera
Whitaker added protist and added Fungi, this was confusing as it showed parallel development of Euks and Proks)
NO: What is Monera, basis?
by Heckel
- defined microbes that aren’t protists, but “single-celled prokaryotic organisms” aka BACTERIA
*however, there was no molecular evidence to support it was
based on a
1. “removing organisms that don’t belong principle”
2. observable features
NO: How were bacteria and Archea grouped, what did WOESE think
*bacteria and archaea were both grouped as Monera because they are single-celled prokaryotes”
*illogical because its based on what is not here a false evolutionary hypothesis, not taxonomic groupings
*archea and bacteria are phlyogenitically different so Moner a is fake
NO: Why could Monera not fit in procaryoye kingdom
- Eukaryotes were divided into 5 kingdoms, adding proks as a kingdom would devolve those 5 kingdoms
*cannot have 5 and 2 kingdoms at the same time
*people believed Pro => euk, putting them on the same level was troublesome
NO: After all the Monera BS what was left out, how did this change things up
- 5 kingdoms view or Pro/Euk view did not account for archea
*Archea are phylogenetically different
*Brought up interest in archaebacteria and how they might be related to the other “kingdoms”
NO” Describe the lack of unifying definition of procaryote
- there was only an artificial definiion, could not be used in taxonomy
*was only based on things that were not eukaryotes
For example: Euks have membrane bound nucleus, Proks do not
=>the euk definition is unifying while the pork is ununifying
=>must only use taxonomic relvalent COMMON characteristics like none exist for all prokayroyes
=> Some scientist argues that it should only be used in historical context and not even as adjective
NO: Characteristics of the three domains (Archaea, Bacteria, Eukarya)
Membrane bound organelles: ?, +, +
Nucelar membrane: -, -, +
Ppt cell wall: -, +, -
Membrane Fatty acid: branched, straight, straight
Initiator tRNA: methionine, formly-methionine, methionine
Chloramphenicol: R, S, R
Diptheria toxin: S, R, S
16S RNA: dissimilar, dissimilar, dissimilar
Discuss chromosome set up in Bacteria, Eukarya and Archea.
Membrane lipids are the same in archaea and eukarya
In bacteria
* there are circular chromosomes
* some linear
*some more than one chromosome
*but not all the essential genes are on one single chromosome
In eukarya
* There are multiple chromosomes
* some eukarya have single chromosomes per haploid set
* Dont have circular genomes unless in organelles
Archea
*only one known with more than one chromosome
Discuss bacteria and archaea with more than one chromosome.
Bacteria:
* Vibrio
* Brucella
* Agrobacterium w/ 4 replicons
Archea: Halocrula has two, which is the only one known with more than one chromosome
What is the chromosome set up in agrobacterium?
4 replicons with 2 chromosomes (1 circular, 1 linear, 2 plasmid)
NO: Issues and more insights from Woese’s paper
- distances between trees are not artistic; length is the number of mutations between two organisms
*Current data has really changed this tree, in Woese paper the time of divergence between archaea and eukarya is too late
Define mutations in the context of evolution.
- they cause differences between species; species diverge as mutation accumulate
*happen at a very low rate over time and can be correlated to evolutionary distances
What are 16S rRNA genes
- molecular chronometer in all cells
*very slowly evolving because it is conserved
*large enough to have sequence diversity but small enough to make sequencing practical
