Lectures 3&4 Flashcards
Very rapid rates of cell division with generation times between 20 min and 3 hrs
binary fission
The most common source of genetic variation
mutations
Genes are taken up from the surrounding environment
Transformation
Transfer of genes between prokaryotes via pilus
Conjugation
Genes are transferred between prokaryotes by viruses
Transduction
Transformation, conjugation, and transduction can lead to
horizontal gene transfer (not from mother cell to daughter cell but from cells that are not related to each other)
A process that does NOT occur in bacteria Mutation Chemotaxis Meiosis Transduction Conjugation
Meiosis
If a nonpathogenic bacterium were to acquire resistance to ABX, could this strain pose a health risk to people?
Yes, it could transfer ABX resistance genes to a pathogenic bacteria via horizontal gene transfer
Obtain energy from light and carbon from CO2
ex) Cyanobacteria
Photoautotrophs
Obtain energy from the oxidation of inorganic molecules and carbon from CO2
ex) Sulfobus (archaea)
Chemolithoautotrophs
Obtain energy from light and carbon from organic molecules
Photoheterotrophs
Obtain energy and carbon from organic molecules
Chemoheterotrophs
decomposers that absorb nutrients from dead organic matter, recyclers of the biosphere
Saprobes
Absorb nutrients from living organisms
Parasites
Symbiotic relationship that is beneficial to both organisms
Mutualism
Which mode of nutrition is unique to prokaryotes Photoautotrophs Chemolithotrophs Photoheterotrophs Chemoheterotrophs
Chemolithotrophs
Photoheterotrophs
Prokaryotes that require oxygen
Obligate aerobes (salmonella)
Prokaryotes that use oxygen if it is present but can grow without it
Facultative anaerobes (E.coli)
Prokaryotes that are poisoned by oxygen
Obligate anaerobes (methanogens)
Key steps in the cycle of nitrogen are performed by prokaryotes
Nitrogen cycling
All organisms need nitrogen for
making amino acids to build proteins
Only some bacteria convert N2 in the air into
forms that can be used by other organisms
N2 –> NH3 –> NO2 –> NO3–> N2 performed by
Chemolithoautotrophs
Some prokaryotes invade the tissue of a host organisms
Tuberculosis (lungs)
Some prokaryotes produce exotoxins
Botulism (botox: paralyzes the muscles)
Some prokaryotes produce endotoxins (toxin is not released from the cell but is apart of the cell)
Salmonella
Prokaryotes can naturally aid in bioremediation
Decomposers
Prokaryotes can fix nitrogen in the air into a form that plants can absorb
Nitrogen metabolism
Prokaryotes called ____ are photosynthesizing microscopic organisms that inhabit the upper layer of oceans and bodies of fresh water
phytoplankton
The oldest group of organisms ad the most abundant on earth
Prokaryotes
The origin of earth is 4.6 billion years ago, the first prokaryotes arrived ____
3.8-3.5 BYA
Classification of prokaryotes is based on ____
molecular approaches
One common approach for classifying prokaryotes is to compare the nucleotide sequence of genes that code for ____
ribosomal RNA, organisms with more nucleotides in common are more closely related
Most prokaryotes have not been cultured and many are being discovered from ____
DNA sequence data
Unicellular
Lack organelles
Lack a nuclear envelope
Circular molecule of DNA
Prokaryotes
Cell walls with peptidoglycan
One type of RNA polymerase
Genes without introns
Eubacteria
Cell walls without peptidoglycan
More than one RNA polymerase
Some genes with introns
Archaea
Archaea that live in anaerobic conditions: marshes, intestines of animals
Methanogens
Archaea that live in extreme high or low temps, high salt, or high pressure
Extremophiles
Eukaryotic cells are generally ____ in diameter
Prokaryotic cells are ____ in diameter
10-100 um
1-5 um
What are the three shapes of prokaryotic cells
coccus- sphere
bacilli - rod
spirilla - hellical
Some species of prokaryotic cells tend to ____
aggregate transiently (aggregate and then separate)
Bacteria adhere to each other and to a surface via a polysaccharide matrix
Biofilms
Permanent aggregates of cells, that are identical, contain two or more specialized cell types
True colonies
In colonies if the cells separate then they CAN ____
survive
cell shape, physical protection, and prevents bursting of prokaryotic cells
cell wall
Have cell walls composed of peptidoglycan
Eubacteria
_____ bacteria tend to be more pathogenic
Gram negative
A rather rigid layer outside the cell wall. Formed by proteins and glycoproteins. Functions in protection and adhesion
S-layer
Gelatinous layer outside the cell wall. More common in Eubacteria. Protects the bacteria against host defenses and glue cells together.
Capsule
The capsule is important for the formation of ____ and ___
biofilms
bacterial colonies
Surface appendages that help the bacteria to attach to various surfaces such as the surface of the host or to another bacteria
Pili/pilus
Prokaryotic ____ is thinner than that of eukaryotes and is made of the protein flagellin. About half of prokaryotes can move through the use of this appendage.
Flaggela
Some flagellated prokaryotes can move towards or away from a particular stimulus
Chemotaxis
In many bacteria infolded regions of the plasma membrane participate in ___ and ____
respiration and photosynthesis
The internal membranes of prokaryotes are folded because (2 reasons)
increased surface area to perform the task
proton gradients form across the spaces and produce ATP
The plasma membranes of archaea differ from those of bacteria and eukarya
Form monolayer
Diff bonds
A double stranded DNA molecule in the form of a ring
Genome
Small rings of bacterial DNA. Can confer bacterial ABX resistance or the ability to use certain nutrients.
Plasmids
Smaller than in eukaryotes and also differ in protein and RNA content
Ribosomes
Differences between Eukaryotes and Archaea
3 things
Types of RNA polymerases
Plasma membrane structure
Cell wall structure
Cells of prokaryotes are haploid which means they
cannot have meiosis
In eukaryotic organisms the enzymes for cellular respiration are located within the mitochondria. In prokaryotic organisms some of these enzymes are attached to
enfolded regions of the plasma membrane
Very rapid rates of cell division with generation times between 20 min and 3 hrs
Binary fission
Replication of the bacterial chromosome. The daughter chromosomes bind to the plasma membrane. Cell growth results in the separation of chromosomes. The plasma membrane and the cell wall grow inward. Formation of 2 daughter cells.
Binary fission
Under unfavorable conditions many bacteria can form ___ which consists of bacterial chromosomes surrounded by a thick wall
Endospores
