Lecture 26 Microbial Taxonomy Flashcards
Cells, organelles (like mitochondria and chloroplasts), and all major metabolic pathways evolved from ____
early prokaryotic cells
Common system of classification that has been recently debunked by phylogenetic data.
the Five Kingdom System
Common system of classification based on phylogenetic data
the Three Domain System
What are the three domains of life?
Bacteria, Archaea, and Eukarya
Endosymbiotic theory
the theory that cell organelles such as the chloroplast and mitochondrion arrised from the engulfing of prokaryotic bacteria
Information that supports the endosymbiotic theory
mitochondria have their own DNA, ribosomes, fission method, and have two membranes
Three domains: cell wall
archaea have no peptidoglycan, bacteria have peptidoglycan, eukarya have carbohydrates
Three domains: membrane lipids
archaea have branched carbon chains, bacteria have straight carbon chains, eukarya have straight carbon chains
Three domains: first amino acid in protein sysnthesis
archaea use methionine, bacteria use formylmethionine, eukarya use methionine
Taxonomy
the science of identifying, naming, and organizing living organisms into systems of classification
Why is taxonomy important?
provides a reference for identifying organisms, provides universal names for organisms, organizes organisms into categories
Phenotype
analysis of physical attributes
Examples of phenotype analysis
morphology, gram reaction, biochemical, nutritional, physiological, pH, antibiotic sensitibity
Genotypic
analysis of the genome
Examples of genotypic analysis
GC content, plasmid analysis, DNA fingerprinting, DNA hybridization, gene sequence analysis (whole & 16rRNA analysis, conserved genes analysis, multigene analysis)
Phylogeny
the study of the evolutionary history of organisms
What is 16s rRNA?
a short strand of RNA commonly used for genotypic analysis
Why is 16s rRNA so commonly used?
present in all cells and always has the same function (lines up mRNA), has enough sequence information, contains variable and constant regions, no horizontal transfer
What do variable regions tell us?
closely-related species
What do constant regions tell us?
distant relationships (same genus)
Horizontal transfer
the movement of genes between different genomes
What is the RDP?
the Ribosomal database project- a database with about 3 million 16s rRNA sequences available
How many species on the RDP are well-characterized?
7,000
How many species on the RDP are partially identified?
10,000
What is the estimate for the total microbial species range?
10^7-10^9 (HUGE RANGE)
How many of all microbial species can we cultivate?
<= 0.1%
How many cells are in 1 mL of surface water?
10^5 cells/mL
How many cells are in 1 g of surface soil?
10^8 cells/g
