Early Earth and Prokaryote Flashcards
when was the Earth formed?
~4.5 bya
when was the earliest life form found?
~3.5 bya
what is the earliest life from known as?
LUCA - last universal common ancestor
what were the earliest fossils found? where?
prokaryotes found in sedimentary rocks called stromatolites
why did the layers in the rocks of stromatolites form?
the prokaryotes had slime layers/capsule and sediment would have stuck to them
when did the first photosynthetic prokaryotes originate? who were they?
~2.5 bya
cyanobacteria
what did photosynthetic prokaryotes do?
their waste product O2 created an aerobic environment
how long were prokaryotes the sole inhabitants of Earth for?
~2 billion years
what two groups can prokaryotes be split into?
Archaea and Bacteria
when did eukaryotes first arise? how?
~1.7 billion years ago
endosymbiosis - the coming together of prokaryotes
for nearly 90% of its existence, life on Earth has been confined to what environments?
H2O
what were the first land organisms?
plants in a mutualistic relationship with fungi living on the roots
what do most biologists agree that life evolved from?
evolved from inorganic materials that becomes ordered into the the molecules of life
what were these inorganic molecules able to do?
replicate and perform metabolism
early condition of the earth
lightning, volcanic activity, meteorite bombardment, acidic oceans, and high radiation were all more intense in the primordial universe
what do some scientist postulated that the primitive earth favored?
favored reactions that formed organic compounds from inorganic sources
why cant inorganic sources form organic compounds present day?
the atmosphere is rich in O2 and O2 affinity for electrons attacks chemical bonds
making organic compounds requires what? what provided this?
much energy probably provided by lightning and UV radiation because they early Earth lacked ozone (O3)
who created laboratory conditions comparable of those to primordial Earth?
Miller in conjunction with Urey
what did the primordial lab atmosphere consist of?
CH4, NH3, H2O, H2
what mimicked lighting in the lab?
sparks that were discharged in the synthetic atmosphere
what happened to the solution in the flask?
went from clear to murky brown as a variety of organic compounds, amino acids, and monomers had formed
“primordial soup”
what happened to the monomers in the flask? without the help of what?
come together to form polymers without the aid of enzymes, unlike monomers today
how did polymerization occur in early earth?
in vitro when monomers are dropped onto hot clay, sand, or hot rock
this process evaporates water and concentrates monomers that then form proteinoids
what are proteinoids?
polypeptides, primary level, made by abiotic means
why might’ve clay been important in polymerization?
monomers could bind to charged sits on clay particles
clay could’ve functioned as a lattice that brought monomers close together and then metal ions could function as catalysts joined them into polymers
what is an alternative to clay?
Fe pyrite - fool’s gold
that could’ve provided charged surface and electrons from this iron/sulfur compound to support bonding between monomers
what could have living cells have been preceded by?
protobionts - “early life”
droplets of macromolecules that maintain an internal environment separate from their surroundings
what properties of life do protobionts show?
metabolism and respond to a stimulus
what do protobionts produced in labs have
surrounded by a shell that is semipermeable and some form a phospholipid bilayer
what was the first genetic material?
RNA
what happened as protobionts droplet grew?
they split and split again and their molecules would become diluted if they could not replicate before division
if a metal atom is added as a catalyst, what happens to the RNA nucleotides made?
it goes from 5-10 to sequences up to 40 nucleotides long copied with less than 1% error in base-pair rules
what are the first proteins believed to be made from?
RNA alone
what would’ve the first proteins made been?
enzymes that aided in replication of RNA
since laboratory simulations cannot prove that life evolved this way, what is another idea?
life on Earth can from space
panspermia - idea that meteorites hitting early Earth brought organic compounds with them like monomers and cells
what is the debate for where life began?
most favor shallow water or moist sediments as the most likely sites for life’s origins
now some feel that life evolved in hydrothermal vents and early life lived off of sulfur compounds (H2S) and it would’ve protected the first life forms from the inhospitable surface of Earth
what effect does the change from 5 kingdom classification to 3 domain systems have?
it assigns more significance to the ancient evolutionary split between bacteria and archaea by using the super kingdom/domain
older word for bacteria
monera
where are prokaryote on earth?
almost everywhere on earth
how many prokaryotes are in a handful of soil?
more than the total number of people that have lived
what is the largest bacteria the size of?
a period
how much of prokaryotes are dangerous?
only a minority of prokaryotes cause diseases and a majority are essential to all life of Earth
how are prokaryotes essential?
some decompose dead organisms, returning essential nutrients to the soils which plants then use
how many prokaryote species are there?
an estimated ~4 million species on earth
what does archaea mean?
ancient
what type of environments did archaea inahbit?
extreme environments such as hydrothermal vents or geysers and volcanoes
most prokaryotes are what type of cells?
unicellular
three most common shapes of prokaryotes
coccus (spheres)
bacilus/bacilli (rods)
helical (spirilla and spirochetes)
two coccus
diplococcus
many coccus
streptococcus
grape of coccus
staphylococcus
what do the cell walls of prokaryotes prevent them from doing?
bursting in a hypotonic environment
what can happen to prokaryotes in a hypertonic solutions?
plasmolyze and die
where is peptidoglycan found?
only in the cell walls of bacteria and not archaea
what two groups is bacteria separated by?
gram negative and gram positive
what is peptidoglycan made of?
consists of sugars and polypeptides
gram negative
rose color
cell wall is anchored between two membranes
gram positive
purple
lost of peptidoglycan
what bacteria is more disease causing why?
gram neg
toxic lipopolysaccharides
antibiotics have difficulty getting at the protected peptidoglycan layer of the cell wall
are prokaryotes motile?
about half
how do motile prokaryotes move?
use their flagella that rotates like a corkscrew allowing them to move in highly viscous environments like mucus in the throat
three parts of a flagella
protein
hook
basal apparatus
taxis
prokaryotes capable of moving toward or away from a stimulus
how are some prokaryotes able to tell from up and down?
by magnetic particles in them that orient themselves towards Earth’s magnetic field which can help them find nutrient-rich sediment at the bottom of ponds
what do prokaryotes lack?
nucleus and other membrane bound organelles
nucleoid
single DNA strand that is formed into a circle
plasmids
small circles of DNA that contain a few genes
what do the plasmids often contain genes for?
antibiotic resistance and from the metabolism of unusual nutrients
how are plasmids replicated?
separately from the nucleoid region and are readily transferred between prokaryotes during conjugation/horizontal transfer
how is a prokaryotic ribosome different from a eukaryotic one? how is this important?
it is smaller;
some antibiotics bind to the ribosome of prokaryotes only and block protein synthesis
what are the two ways antibiotics work?
on the cell wall and ribosomes
what is the source of antibiotics from?
prokaryotes themselves who make them to compete with other prokaryotes, from some protists and fungi
how do prokaryotes reproduce?
binary fission
do prokaryotes perform mitosis or meiosis?
no
how does genetic variation come about in prokaryotes?
mutations
transformation (gene taken up from environment)
transduction (genes transferred from a virus to a prokaryote)
conjugation ( genes from one prokaryote to another prokaryote)
how is gene movement like in prokaryote?
unilateral
what does cooling and refrigerating do to food?
slow spoilage/prokaryote growth
how is uncontrollable colony growth kept in check?
by the depletion of some nutrient or accumulation of wastes that poison the colony
endospores
heat-resistant/durable structures
when do prokaryotes form endospores? why?
when it is exposed to a trauma like lack of nutrients or water or extreme heat or cold to avoid death
how to kill endopores?
autoclaves
how to make endospores reporduce?
place them in a hospitable environment where they can rehydrate
energy source of photo-autotrophs. ex?
light
plants, algae, cyanobacteria
energy source of chemo-autotrophs. ex?
inorganic chemicals
bacteria near deep sea vents life of H2S
energy source of photo-heterotrophs. ex?
light and organic compounds
venus fly trap
energy source of chemo-heterotrophs. ex?
organic compounds
humans
what are majority of prokaryotes?ex,
chemo-heterotrophs
saprobes
what are saprobes
microorganisms that live off dead organic matter and parasite that live off a live host’s body fluids
what are some some prokaryotes able to do with the nitrogen cycle?
nitrogen fixation - N2 gas into NH3 ammonia
what do prokaryotes living in the soil with ammonia?
convert it into nitrite NO-2 and nitrate NO-3
obligate aerobes
use oxygen for cellular respiration and cannot grow without it
faculatative anaerobes
use oxygen if present, but can also grow by fermentation
obligate anaerobes
poisoned by oxygen
what were the earliest cells on earth?
chemo-autotrophs that obtained their energy from inorganic chemicals like H2S and Fe+2
FeS2 + H2S –> FeS2 + H2 + free energy
how were the chemoautotrophs?
opportunistic as well obtaining some nutrients by absorbing organic compounds when available
first photosynthetic prokaryotes that made O2
cyanobacteria
another word for cyanobacteria
blue-green algae (prokaryote)
how did cyanobacteria change the world?
releasing O2 as a by-product
when did cyanobacteria evolve?
2.5-3 bya
cyanobacteria were able to perform photosynthesis without? what did they have instead?
the aid of chloroplast structures;
infoldings of the plasma membrane where bacteriochlorophyll is located
how do purple and green sulfur bacteria photosynthesize?
H2S–> no O2
how do cyanobacteria photosynthesize?
use H2O and make O2
how much in common do archaea have with bacteria?
as much as they do with eukarya
3 main groups of archaea
methanogens
halophiles
thermophiles
what do methanogens do?
produce CH4 and are among the strictest of obligate anaerobes
where do methanogens live?
in swamps and marshes and are often used in sewage treatment to break down waste in septic tanks
in the guts of many ruminants and some people
where do extreme halophiles live?
salty environments like the Dead Sea, San Francisco Bay where commercial salt is made because their presence in their ponds turn them reddish/yellow or purple and are harmless
where do extreme thermophiles live?
hot sulfur springs of Yellowstone National Park and in hot hydrothermal vents beneath the ocean floor that can be 105 C/221 F
what account for most prokaryotes? how many groups are there? examples?
Bacteria
12
cyanobacteria, gram positive and negative
what do prokaryotes decompose?
recycle essential elements like CHON and SPONCH back into ecosystems then these elements are available for other organisms
what were Koch’s postulates based upon?
linking diseases to specific bacteria
what 4 criteria did Koch use?
- find the pathogen in a diseased animal
- grow the pathogen on agar and ID it with a microscope
- infect a healthy animal with the pathogen
- grow the pathogen again on agar from the dead animal and ID it with a microscope
of the pathogenic/disease causing prokaryotes, what are exotoxins?
secrete toxins
botulism
of the pathogenic/disease causing prokaryotes, what are endotoxins?
toxins in their cell membrane
gram - have lipopolysaccharides
where can botulism grow and what can it do?
grow in canned food
one gram is enough to kill 10^6 people
