BMSC210 CH4.5 Flashcards
What does the trunk or root of a phylogenetic tree represent?
Common ancient evolutionary ancestor
What do the branches of a phylogenetic tree represent?
Evolutionary descendants
What does LUCA stand for?
Last universal common ancestor
What do the deeply branching bacteria represent?
Earth’s earliest life forms
Why are the deeply branching bacteria called ‘deeply branching’?
They stem from the common root of life, deep and close to the LUCA root
What do the earliest branches in phylogenetic trees represent?
Organisms most closely related to LUCA.
What is the significance of deeply branching bacteria?
They may provide clues about ancient and now extinct forms of life.
What are the living ancestors of deeply branching bacteria called?
Thermophiles or hyperthermophiles.
Where do thermophiles or hyperthermophiles thrive?
At very high temperatures.
What type of environmental conditions do the proposed first organisms thrive in?
Hot environmental conditions.
What is unique about the class Aquificae and their adaptation to conditions?
Aquificae includes bacteria adapted to the harshest conditions on Earth.
At what temperature do bacteria from the genus Aquifex thrive?
Temperature higher than 90 °C.
Where can the species A. pyrophilus be found?
Near underwater hot springs.
What are the extreme environments where Aquifex bacteria can be found?
Volcanoes and thermal ocean vents
What is the temperature of water where Aquifex bacteria can thrive?
138 °C
What type of substances do Aquifex bacteria use as nutrients?
Inorganic substances
What was the condition of the earth when the ancient bacteria started evolving?
Hot and lacked an atmosphere
What type of bacteria does the class Thermotogae represent?
Hyperthermophilic and some mesophilic anaerobic gram-negative bacteria
What is the genus of bacteria that is able to use a variety of organic substrates and produce molecular hydrogen?
Thermotoga
Where does T. maritima, a species of Thermotoga, live?
Near thermal ocean vents
What is the temperature at which T. maritima thrives?
90 °C
Where does T. subterranea, another species of Thermotoga, live?
In underground oil reservoirs
Why is D. radiodurans considered a polyextremophile?
Because it can survive under many different kinds of extreme conditions
What makes D. radiodurans unique?
Its ability to withstand doses of ionizing radiation that kill all other known bacteria
What is the special ability of D. radiodurans attributed to?
Some unique mechanisms of DNA repair
