Prokaryotes, Bacteria and Archaea Flashcards
What two domains consist in prokaryotes? How was that determined?
- Domain Bacteria
- Domain Archaea
- determined through RNA evidence
Where were the first fossilized prokaryotes found?
In stromatolites (rock-like structures composed of layers of bacteria mats)
Prokaryotes outweighs all eukaryotic organisms by ____%
10%
What is one advantage that prokaryotes have over eukaryotes?
They live in diverse habitats where eukaryotes can’t live
What are the 5 structures of a prokaryotic cell?
- Fimbre –> helps them sense their outside environment
- Plasma membrane cell wall
- Circular DNA
- Pilus (involved in reproduction)
- Flagellum –> helps them move
What is Taxis in terms of prokaryotic cells?
taxis is a movement towards or away from stimuli
What are 4 characteristics of prokaryotic cells?
- they have no nucleus –> instead they have circular rings of DNA and no membrane bound organelles
- They contain plasmids –> which are small rings of additional DNA, which get transferred during conjugation (sexual reproduction)
- Lack membrane bound organelles –> infolding of membrane does exist though (called thylakoids)
- Small and unicellular
What composes the prokaryotic cell wall? What does it do?
The cell wall is composed of peptidoglycan
- which keeps cell shape, helps protect the organism and prevents cell from exploding when its placed in a hypotonic environment (fewer solute in environment than cells)
What are two types of bacterial cell wall? What is the difference between them?
- Gram + –> have peptidoglycan wall which traps crystal violet dye and turns purple
- Gram - —> lack peptidoglycan but instead have lipopolysaccharide layers outside of the cell wall and do not absorb the crystal violet die
What is the importance of determining which type a bacterial cell wall is?
its important to determine which cels can resist antibiotics.
- Gram negative species are often more pathogenic because their outer lipopolysaccharide layer can contain toxins and resist antibiotics
How do most prokaryotic cells reproduce? What is the result of their reproduction?
reproduce asexually (through binary fission) but they have VERY HIGH MUTATION RATES over a short generation of time and that is what increases their genetic diversity
How do bacteria exchange genetic information?
through genetic recombination via horizontal gene transfer
What are the two methods of horizontal gene transfer in bacteria? Describe them
- Transformation: when naked, random DNA is picked up from dead bacteria in the environment and they incorporate it as their own
- Transduction: When DNA is transferred by a virus (bacteriophage). –> occurs when a virus (with its own RNA) injects a bacteria as its host, and the bacteria start reproducing part of the virus’s RNA and the virus goes onto another bacteria to make it its host and accidentally transfers some of the DNA from the previous bacteria into the new host bacteria therefore incorporating that into their genome
What is bacteria cell conjugation?
When a donor cell transfers DNA (through plasmids) to another cell by attaching its plus onto another and the other cell receives DNA in one direction (not back and forth sharing).
How do bacteria obtain nutrients?
some bacteria are autotrophs (make their own energy) and some are heterotrophs (contain enzymes that digest organic molecules in environment thats absorbed by their membranes)
