24- Bacteria, Archea & Viruses Flashcards
the prokaryotic cell
- all unicellular
- no nucleus/membrane-bound organelles
- replicate via binary fission
- often have 1 single chromosome (haploid)
Plasmids
- smaller DNA loops in Prokaryotes
- often contain specialized alleles
Lateral gene transfer
- transfer of genes from one species to another species in the same generation
- 3 mechanisms:
- transformation
- transduction
- conjugation
Transformation
- prokaryote uptakes foreign DNA for outside of cell via proteins which recognize DNA of similar species
- Then integrates new DNA into its own, changing its genotype/phenotype
- the foreign DNA come from a Lysed cell
Transduction
- bacteriophages transfer DNA of one host to another (accidentally)
- usually an error in viral replication
Conjugation
-DNA transfer from one prokaryote to another via a sex pilus which temporarily joins 2members of the same species
Shape (domain bacteria)
- cocci (spherical)
- bacillus (rod-shaped)
- spiral (spiral-form)
Organizational arrangements (domain bacteria)
- diplo- (2)
- strepto- (chains)
- Stahpylo- (clusters/packets)
Colony morphology (domain bacteria)
- a macroscopic structure of bacteria is often easier to identify
- form, margin, & elevation
Cell surface features (domain bacteria)
- Gram positive (thick layer of peptidoglycan)
- Gram negative (thin layer of peptidoglycan between 2 membranes)
Hadobacteria
- high temperature clade
- some can withstand radiation & degrade nuclear waste
Hyperthermophillic bacteria
- live in places hotter than hadobacteria (volcanic vents & hot springs)
- some live in underground oil reserves
Firmicutes Bateria
-most are gram positive
-some produce endospores
(Anthrax/staph infections)
Endospore
A resting structure (dormant cell) that can survive harsh conditions, and reanimate when conditions are better
Actinobacteria
- most are pathogenic
- produce antibodies
- gram-positive
- develop highly branched filaments
Cyanobacteria
(Blue-green bacteria)
- first photosynthesizers
- used chlorophyll a and releases O2 - many nitrogen fixers
- colonies have heteromorphic cells
heteromorphic cells
- vegetative cell
- for growth & photosynthesis - Endospores
- Heterocysts
- for nitrogen fixation
Spirochete bacteria
-gram negative
-spiral shape
-have axial filaments for movement
-many are parasitic
(Syphillis/Lyme disease)
Chlamydia bacteria
- very small
- obligate parasites
- complex life cycle that has 2 forms of cells
- reticulate bodes
- elementary bodies
- many diseases
Proteobacteria
- largest and most diverse clade
- mostly gram negative
- Use light energy to metabolize high energy sulfur bonds
- Nitrogen fixers
- E. Coli
- many pathogens (salmonella/bubonic plague)
Domain Archea
- much less well known
- many extremophiles
- Lokiarcheata is the closest living relative of domain Eukarya
- lack peptidoglycan, and contain distinct lipids that are unique to this domain
Extreme Archean habitats
- thermophiles (high heat)
- acidophiles (low pH)
- methanogens (produce methane when they reduce CO2 for energy)
- halophiles (high salinity)
Nutritional adaptations of eukaryotes
- Photoautotroph (light & CO2)
- photoheterotroph (light & organic compounds)
- chemoautotroph (inorganic compounds & CO2)
- chemoheterotroph (organic compounds & organic compounds)
*photoheterotrophs & chemoautotrophs are only found in prokaryotes
Metabolic adaptations of prokaryotes
- obligate aerobes
- Must use O2 for cellular respiration
- obligate anaerobes
- poisoned by O2, must live in oxygen-free environment
- facultative anaerobes
- use O2 if present, but can also utilize anaerobic metabolic pathways
Nitrogen fixation
- Eukaryotes can use very few forms of nitrogen
- like ammonia NH3
- some prokaryotes convert N2 to NH3 (nitrogen fixers)
- lead to symbiotic relationshipships
Pathogenic bacteria
- cause disease primarily from releasing toxins
- exotoxins
- proteins releases by living bacteria - endotoxins
- liposaccharides released when certain bacteria grow or die
- exotoxins
