Phenetic: Numerical taxonomy Flashcards
phenetic ?
based on Overall similarity
phenetic is a traditional method for the classification of prokaryotes introduced 200 years ago
by
Michael Adanson
classification 3 characterics?
– All characteristics =equal importance (unbiased).
– Classification base on as many features as possible.
– Organisms should be grouped on the basis of overall similarity.
some phenotypic characteristics ?
- Morphology
- Motility
- Physiology
- Cell lipid chemistry
- Cell wall chemistry
- Other traits
what is constructed to illustrate the relationship between the species?
dendogram
Phenon?
group of organisms that have
characters in common
what’s phylogenetic?
class evolutionary relationships
A mutation is a change in the?
genome of an organism (nucleotide change,
insertion, deletion).
Gene duplication, gene loss and horizontal gene transfer what’s that?
acquisition of a whole
new gene from another organism
Genetic change may?
be silent,deleterious,beneficial
Evolutionary pressure (stress) selects or discards mutation.
-
Adaptive mutations improve
fitness of an organism, increasing survival in its
environment.
Silent mutations may be beneficial in other environments
allowing the microorganism to
colonize new niches.
Deleterious mutation are usually
lost
Accumulation of mutations
may lead to speciation (rise of a new species
who defined archea by phylogenetic taxonomy of 16S ribosomal RNA,
Carl Woese(1970)
Contribution of Carl Woese in subunits?
Sequencing of the small subunit rRNA (SSU rRNA):
16S rRNA in prokaryotes, 18S rRNA in eukaryotes
carl woese established?
presence of three domains of life:
Bacteria, Archaea, and Eukarya
carl woese provided?
a unified phylogenetic framework for
Bacteria
Comparative rRNA sequencing is a routine
procedure that involves the following:
- amplify gene encoding SSU rRNA
- Sequencing of the amplified gene
- Analysis of sequence in reference to other sequences
rRNA sequencing is used to infer the
phylogeny of prokaryotes and other
microorganisms
dans un photo de la structure de 16s rRNA what are the highly variable regions?
the one that have color
how is called the accumulation of neutral mutation over time?
genetic drift
The evolutionary relationship between two organisms is directly correlated to the number of \_\_\_\_\_ that have accumulated in each one.
mutation
if there are few differences in the structure of two 16s rRNA ?
they are closely related ( E.coli and Salmonella )
if there are many differences in the structure of two 16s rRNA ?
diverge a long time ago (Bacteria and Archea)
Comment tu obtient t sequence?
1-Isolate DNA
2-Amplify 16s gene by PCR
What do u do with ur sequences?
Align sequences
why do u align sequences?
to take into account insertion-deletion
Construct phylogenetic trees
graphic illustration of the relationships among
sequences
Branch length represents the _________that have occurred along
that branch
number of changes
nodes
putative common ancestor
Branches define the order of
- descent
- ancestry of the nodes
Building phylogenetic trees?
1-the first step in making a tree is to align sequences
2-distance matrix is calculated from the number of sequence differences
3-the tree is constructied by adding nodes to join lineage that have the fewest differences
