Lesson 3: Microbial Phylogeny Flashcards
the field of study dedicated to
understanding the evolutionary
relationships between different groups of microorganisms, primarily bacteria, and archaea
Microbial Phylogeny
Importance of microbial phylogeny
-development of antibiotics for infectious disease by identifying their vulnerabilities
-bioremediation strategies using microbes
-exploring earth’s diversity
Challenges in Microbial Phylogeny
Similarites of microbes
Horizontal gene transfer
TECHNIQUE
compares sequences of different microbes to infer
evolutionary relationships.
Comparative genomics
TECHNIQUE
describe WGS
- comprehensive data of genomic sequences
-provides data from AMR genes
-time consuming and expensive
______depict evolutionary
relationships between microbial groups over time using data from various techniques.
Phylogenetic tree
Benefits of Studying Microbial Phylogeny
- improved objective classification instead of morphology-based
-functional prediction using mathematical models for exploring microbial function
-understanding interaction of microbes with their ecosystems
-interaction and relationship with other organism in the community
-sytematic study using methods beyond genomics
How is microbial phylogeny being study
Polyphasic analysis: genotypic, phenotypic and phylognetic analyses
Molecular phylogeny analysis
DNA sequences
This classification involes, phenotypic, morphological (size, shape, structure), physiological, biochemical and genetic sequences
Polyphasic Analysis
Why do we analyze DNA sequences to investigate microbial phylogeny
DNA sequences show history of evolution
mutations accumulate in DNA overtime
More mutations indicates longer evolutionary distance
Obtaining DNA sequences
PCR- amplify genes
SSu rRNA- highly conserved, easy to sequence
Genes inherited and are used for alignment
homologous genes
adds gaps to
ensure positional homology
Sequence alignment
Phylogenetic Tree elements
Rooted- ancestral position
Unrooted: relative but not most ancestral node
Branch lengths: number of evolutionary changes
These values indicate confidence levels in the nodes
Bootstrap values
Limitations in phylognetic tree
- Difficulty in choosing true tree (limited data)
- Homoplasy convergent evolution (similar traits or features
- horizontal gene transfer
Origin of cellular life
building blocks of life (RNA, nucleotides, AA, lipds) form naturally on earth
Location of life’s origin
Hydrothermal vent on ocean floor
stable conditions
energy sources (inorganic compounds)
Production of key molecules (AA, lipids, nucleotide bases, sugars)
Possible first life form
RNA- first self-replication sysntem ( catalysis)
Evolution of Life
RNA catalytic property was replaced with protein
DNA replaced RNA as the genetic material due to its stability
What is LUCA
Last universal common ancestor 3.8-3.7 BYA
