Intro & Microbial Diversity Flashcards
microbes are _____ meaning are everywhere
ubiquitous
prokaryotes have no ____ or _____ bound organelles
nucleus or membrane bound organelles
4 characteristics of living organisms
- fighting
- fleeing
- feeding
- fucking
what are the two cellular prokaryotes we look at? what is the one acellular thing?
cellular
-bacteria
-archaea
acellular
-viruses
2.5 - 4 billion years ago there was only what?
500 million to 2.5 billion years ago?
earlier then 500million years ago?
2.5-4 = prokaryotes
500mil-2.5billion = microbial life forms only
earlier = everything else
the first eukaryote was ______
uni cellular
describe early earth (3)
- very little oxygen (anoxic)
- highly reducing enviro
- early cells were anerobic
describe cyanobacteria’s role in early earth (3)
were the beginning of oxygen producing photosynthesis
- from anoxic to oxic
- helped evolved eukaryotes!
how could the first cells have formed ? describe (6)
probiont hypothesis (forms a probiont not a cell)
-RNA first to evolve (form spontaneously)
-lipid vesicle forms spontaneously
-lipid membrane forms around RNA (probiont)
-RNA replicates by themselves & catalyzes protein synthesis to
-DNA evolved from RNA
then cellular life as have DNA,RNA and proteins
what is supporting evidence for probiont hypothesis (3)
- RNA can catalyze reactions in modern cells (ribozym = ribosome,spliceosome)
- RNA (act as polymerase) and liposomes can form in vitro by themselves
- organic molecules needed to form RNA can form spontaneously from inorganic molecules under right conditions
evidence for evolution of RNA
- hydrothermal vents
= perfect conditions for inorganic molecules to form organic ones
evidence to carbon date the origin of cells (2)
indirect = presence of compounds only microbes can make - rocks in australia with complex organic carbon compounds
direct = imprints of cell shapes in rocks
- squiggles have the shape of cyanobacterial cells ( streptococci)
how did the first eukaryote evolve ?
endosymbiosis
(cells become engulfed within another)
-mitochondria
-chloroplasts
what model do we focus on?
two domains model:
-bacteria
-archaea (eukaryotes arose from archaea)
what helped change from a three domain to a two domain model?
Lokiarchaeota (Loki)
from a hydrothermal vent in iceland
-first known representative of asgardarchaea !
describe asgardarchaea (4)
prokaryote
- contain a lot of proteins (thought to only be in euk)
- have cytoskeleton filaments ex. actin
- hard to replicate so got this info mainly from metagenomics not cultured cells
compare endosymbiont vs endosymbiotic organelle
endosymbiont - living in symbiosis where one is inside the other
endosymbiotic organelle - loses structures by evolution / independent ability as now relies on larger cell
endosymbiotic organelles have what characteristics of bacteria (5)
- circular DNA
- Nformylmethionine rather than methionine
- replicate via binary fission
- 70s ribosome
- porins in their membrane
evidence of endosymbiosis
bacteria acts similar to mitochondria
- uses nitrate to generate ATP
genus vs species
where did this system come from?
genus = beginning, species = end part
came from carl linnaeus system
define species
- what does it not describe
can sexually reproduce and produce reproductively viable offspring
does not describe
-prokaryotes (bacteria/archaea)
-viruses
rooted vs unrooted phylogenetic tree
rooted - shows the ancestry relationship
unrooted - only shows the relatedness of organisms
why do we use ribosomal RNA to determine microbial taxonomy (3)
- very abundant ( need ribosomes to make proteins)
- very consistent
- hyper variable regions / have variant loop regions which differ between species
what is evolutionary distance
Ed = amount of change in DNA
= # nt differences / total of # of nt
how to tell organisms that are least related
will have highest Ed number
how to tell which domain a microbe comes from
check rRNA!
what classification system do you only see in eukaryotes?
kingdom
what is special about prokaryote classification system
species isn’t the smallest level of classification
- strains
do bacteria have mitochondria/ chloroplasts ?
what about euk, cyanobacteria, archaea?
bacteria - mito yes, chloroplast no
euk - mito yes, chloroplast no
cyanobacteria- yes chloroplast?
archaea- no mitochondria or chloroplast
