What features make SSU rRNA gene sequences ideal for phylogenetic studies?
rRNA - universal presence in all cells, same function in all cells
SSU = small subunit
SSU rRNA - referred to as a “molecular chronometer”; sequence changes very slowly due to functional constraints on the molecule
Random mutations on the small SSU rRNA often have serious negative results, so relatively few changes are passed on
rRNA genes’ overall mutation rates also seem similar between species
- Therefore sequence differences can be quantified between SSU rRNA in diff species to infer relationships
Microbiology
study of microbes, examines microbial interaction, disciplinary basis for molecular biology and biotechnology
microbe vs microorganism
microorganism = archaea, eukaryotes, bacteria
microbes = viruses, archaea, eukaryotes, bacteria
microorganisms for eukarya include:
algae
fungi
protozoa
Robert Hooke
early microscopes!
first description of microbes (fruiting structures of “moulds”)
Robert’s Hooke’s early microscope structure
compound microscope with two lenses:
one bottom one top
Antonie van Leeuwenhoek
- improvements in lens construction allowed first description of bacteria
- “Father of Microbiology”
- first to observe moving bacteria “little animalcules”
____ were first life on earth
microorganisms
microorganisms established ___ conditions (___) –> led to ____ organisms
biosphere
(O2)
multicellularm
microorganisms = >___% earth biomass
> 50%
How can microbes help in biogeochemical cycling?
interact with environment (cycle inorganic molecules to organic molecules and back, e.g., nitrogen-fixing)
Core features of life!
- metabolism
- growth
- reproduction
core features of life achieved by (3)
genetic variation/evolution
response/adaptation
homeostasis
how do microbes get energy?
heterotroph - ingests preformed organic molecules
autotroph - produces organic molecules
fermentation (less ATP)
aerobic respiration (more ATP)
macromolecules in microbial cells
mostly polypeptides (~50%)
then RNA (~15%)
lipids (10%)
sugars (~6%)
DNA (~2-5%)
phylogenetic tree divided into:
bacteria
archaea
eukarya
phylogenetic tree is based on ________
ribosomal RNA (rRNA)
viruses characteristics
- don’t replicate outside of host cell
- little to no biochemical activity outside of host cell
- inert and nonreactive outside of host cell
Origin of life - early conditions
- little O2 in atmosphere
- high temp
- high CO2
- planet surface was chemical soup with reducing atmosphere (a lot of electrons available to give, e.g., CH4, NH3, H2)
- initial synthesis of first macromolecules
origin of life early conditions - planet surface
chemical soup with reducing atmosphere (a lot of electrons available to give, e.g., CH4, NH3, H2)
Stanley Miller with Harold Urey
simulated “spark” that may have started forming organic molecules from primordial soup
- primitive ocean mixture, cloud formation, primitive atmosphere, electrical sparks (lightning)
- a lot of reducing gases
requirements of early life
- genetic information storage
- ability to catalyze biochemical rxns
- a way of separating cell interior from external environment
ribozymes
- RNA behaving like enzymes (excises portion of rRNA)
- rxn catalyst
- genetic information storage
- self-replicating
micelles
- may have been early form of plasma membrane
- instead of bilayer, just non-polar tails together in globule with polar heads outside
