Topic 7: Prokaryotes Flashcards
what are prokaryotes 2 domains
-Domain Bacteria
-Domain Archaea
what the earliest life from
Prokaryotes
they were the first unicellular organisms
-stromatolites:
they are rock-like structures composed of layers of bacteria mats and sediments
why are prokaryotes so successful?
advantages include
-their small size meaning they don’t require much energy to function
-use binary fission-meaning rapid rates of reproduction
-short generation time-able to evolve faster due to the accumulation of more DNA replication errors
overall meaning they are adaptable
prokaryotic cells are composed of
-fimbriae- protein structures located at the surface of bacterial cells
-plasma membrane and cell wall
-circular DNA
-pilus- used for horizontal gene transfer
-flagellum-long tails enables movement
what do prokaryotes lack
-they lack a nucleus, the circular ring of DNA isn’t enclosed by a membrane, like in eukaryotes
-they lack membrane-enclosed organelles like the Golgi apparatus, mitochondria, etc.
what happens when u asexual reproduction fission with short regeneration time
high mutation rate which increases genetic diversity
How do bacteria exchange genetic information
through horizontal gene transfer-(movement of genetic information between organisms)
what are the three types of horizontal gene transfer’s
-transformation: when there is “naked” DNA picked up from the dead bacteria
-transduction: DNA is transmitted from one cell to another via bacteriophage (virus)
-Conjunction-cells make contact via pilus and exchange their DNA
How do prokaryotes obtain Nutrients
either
-Autotrophs-they make their energy from inorganic sources
-Heterotrophs-they make their energy by consuming inorder to get organic molecules
the 2 types of autotrophs are
-chemoautotrophs-use energy obtained by oxidizing inorganic chemicals and CO2 (these are most prokaryotes)
-Photoautotophs- use light energy and CO2 (these are the primary producers that support the food web)
the 2 types of Heterotrophs
-Photoheterotrophs -use light energy and carbon source from organic molecules
-Chemoheterobtrophs- use organic molecules for both energy and carbon source
ecological relationships (5)
- Mutualism-both organisms benefit from the other presence
- Competition-neither of the 2 organisms benefits from the other presence
3.Predation(one eats the other) or Parasitism(one steals the nutrients of the other)-one benefits and the other doesn’t - Communalism- one is benefiting and the other isn’t harmed not benefiting, just neutral
- Amensalism- one is harmed and the other is neutral
prokaryotes are…
symbiotic
-when inside the host , its an endosymbiotic relationship
what is the difference between bacteria and Archaea
-Bacteria have peptidoglycan in the cell wall whereas archaea don’t
-Bacteria respond to antibiotics that inhibit eubacterial growth whereas archaea don’t
-Archaea can live in extremely harsh conditions (extremophiles)
domain archaea are extremophiles meaning…
-they can live in extreme conditions…they are:
Methanogens -live in oxygen-free habitats
Halophiles- live in very salty habitats
Thermophiles- live in very hot habitats
Domain Bacteria: Systematics of Eubacteria
- Proteobacteria (important)
- Chlamydias
- spirochetes
- Cyanobacteria (important)
- Gram-positive bacteria (important)
Domain Bacteria’s cell walls contain what?
contain peptidoglycan
what does peptidoglycan do
it provides:
-cell shape
-protection
-prevents the cell form from exploding when placed in a hypotonic solution (lower solute than cell contents meaning that solution goes into the cell causing it to overfill)
Gram+ve vs. Gram-ve what happens with the gram stain test
the gram stain test is when you expose the bacteria to crystal violet in order to understand whether its Gram +ve or Gram -ve
Gram +ve -have peptidoglycan wall in contact with an external medium which traps purple stains
Gram -ve have a lipopolysaccharide layer outside of the cell wall, thus do not absorb the stain readily- stain pink
Gram -ve are often pathogenic (cause diseases), as the outer lipopolysaccharide layer can contain toxins and resit action of antibiotics
Proteobacteria (what evolved form it )
-are Gram -ve bacteria (contain the lipopolysaccharide)
-include endosymbiotic mutualists like Rhizobium (lives in root nodules or leguminous plants and fixes atmospheric nitrogen to make available for the plant and in return gets carbohydrates
-scientist hyporthizied that mitochondria evolved form the aerobic alpha-proteobacteria through endosymbiosis (since it lives in a host )
Chlamydias
-a pathogenic bacteria
-it lives within animal cells
-has no peptidoglycan in the cell wall, possibly because they live within other cells
Spirochetes
-are pathogenic bacteria
-they are helical bacteria that swim by spiralling
Cyanobacteria (what evolved form it )
-they are photoautotrophs ( meaning they make their energy using light energy and co2)
-they are the cause of oxygen being in our atmosphere billions of years ago since the bi production of photoautotrophs is oxygen
-the chloroplast evolved form the cynanobacteria
pathogenic bacteria
-Gram +ve pathogenic bacteria
-spirochetes
chlamydias
whats the importance of bacteria
-production of cheese and yogurt
-used to decompose sewage treatment
-decompose bioremediation (when an oil spill occurs in order to manage the spill these bacteria are put, and they eat up the oil spill)
-antibiotics
-are essential for the nitrogen and carbon cycle between the atmosphere and water
-makes nutrient available for animals through decomposing
whats oxygenic photosynthesis
when water and another molecule is put in a reaction and the by-product in oxygen
comapring
