Topic 7 - Prokaryotes Flashcards
What is a prokaryote?
a small unicellular organism that lacks membrane-enclosed organelles, meaning no nucleus, but they do have cell walls
What makes prokaryotes so adaptable?
- small size
- binary fission
- short generation time
What makes up the cell wall?
peptidoglycogen
- NOT cellulose
- it provides: cell shape, protection, and prevention from exploding
What is binary fission?
a form of asexual reproduction where one cell is splitting into two daughter cells
How does bacteria exchange genetic info?
- horizontal gene transfer
- transformation
- transduction
- conjugation
What are chemoautotrophs?
produce energy directly from chemicals in the environment, carbon comes from CO2
ex) many prokaryotes
What are photoautotrophs?
use light energy (directly from sun aka photosynthesis) & CO2 , primary producers that support the food web
ex) cyanobacteria
What are chemoheterotrophs?
gets energy by consuming other organisms, carbon comes from compounds
ex) animals, fungi
What are photoheterotrophs?
use light energy (directly from sun aka photosynthesis) cannot use CO2 as their sole carbon source (comes from organic molecules), this case is rare
ex) a few prokaryotes
Define extremophiles
many in the archaea domain, live in extreme environments
Define halophiles
live in very salty habitats, can be any ionic crystalline compound not just NaCl
Define methanogens
live in oxygen-free habitats, produce methane as a waste product
ex) swamp substances, cow & termite guts
Define thermophiles
live in very hot habitats
- many are chemoautotrophs
- some used for PCR techniques
What are gram positive bacteria?
- have peptidoglycan wall
- can trap purple stain
What are gram negative bacteria?
- have lipopolysaccharide layer outside of the cell wall
- DO NOT absorb stain readily
Describe proteobacteria
- mutualistic bacteria
- large & metabolically diverse group of gram -ve
- endosymbiotic mutualists
- ex) rhizobium (fix atmospheric nitrogen & live in root nodules)
Where do scientists hypothesize mitrochondria evolved from?
aerobic alpha proteobacteria (through endosymbiosis)
Describe chlamydias
- live only in animal cells
- no peptidoglycan in cell walls
Describe spirochaetes
- helical bacteria that swim by spiraling
- many are free-living
Describe cyanobacteria
- photoautotrophs
- production of oxygen in the atmosphere
Where did chloroplasts evolve from?
cyanobacteria
What are examples of gram+ve pathogenic bacteria?
- tuberculosis
- leprasy
- anthrax
Why is bacteria important?
- production of cheeses and yogurt
- metabolic & chemical properties
- makes nutrients for other organisms through decomposition
ex) sewage, antibiotics, nitrogen fixation
What are the three domains of life?
- Archaea = closest relative to the Eukaryotes
- Bacteria = most well-known prokaryote
- Eukaryotes
Explain horizontal gene transfer
absorbing DNA from the environment for genetic recombination
Explain transformation
uptake for foreign DNA from dead bacteria in the environment
Explain transduction
DNA being transferred by a virus from past hosts
Explain conjugation
transfer of DNA from one prokaryote to another
What is mutualism?
both organisms benefit from the symbiotic relationship
What is commensalism?
one organism benefits and the other neither benefits nor is harmed, therefore neutral from the symbiotic relationship
What is parasitism?
one organism benefits and the other is harmed in the symbiotic relationship
