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78 terms

Micro test continued

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what are the 4 phases of a bacterial growth curve?
lag, log (exponential), stationary (plateau), and death (decline)
a period of adjustment of a bacterial culture
lag phase
the time required for a bacterial cell to grow and divide
generation time
the time for a bacterial population to double in number
generation time
populations of bacteria in log phase are most susceptible to what?
antimicrobial drugs
populations of bacteria in what phase are most susceptible to antimicrobial drugs?
log phase
What phase is characterized by DNA replication, growth, and reproduction?
log
as toxic waste builds up or food is depleted, bacterial cultures go into the ___ phase where there is no change in the size of the population (# dying= # reproducing)
stationary
a stationary phase has what kind of a change?
none
certain bacteria can undergo sporulation in what phase?
stationary
bacterial cells die, reducing the total number of bacterial cells in the culture in what phase?
death
bacteria exists in what 3 shapes?
round (coccus), rod (bacillus), and spiral (spirilla, spirochete, vibrio)
chains of cocci
streptococci
clusters of cocci
staphylococci
pairs of cocci
diplococci
a ___ bacterial cell is one that is growing and multiplying
vegetative
the hardiest of all life forms
spores
withstands extremes of temps, drying, freezing, radiation, and chemicals that would kill vegetative bacterial cells
spores
bacteria that can form spores have a 2 phase life cycle
vegetative cell and a spore
do most bacteria cause diseases?
no
___ can begin if a bacterial cell is depleted of nutrients or put into a harsh environment: it can remain in this dormant inactive state forever
spore formation
difficult to destroy and is a problem when cleanliness and sterility are important
spores
the breaking of ___ or germination of a spore happens in the presence of water and a favorable environmental stimulus
dormancy
the breaking of dormancy or germination of a spore happens in the presence of a favorable environmental stimulus and what?
water
what resists ordinary cleaning methods that use boiling water, soaps, and disinfectants?
spores
___ are not necessary for a bacterial cell to survive
plasmids
extra chromosomal pieces of circular dna found in the cytoplasm of the bacterial cell.
plasmids
replicate independently of the bacterial chromosome
plasmids
made of dna and code for things not necessary for a bacterial cell to survive
plasmids
can be transferred from one bacteria to another through conjugation, transformation, and transduction
plasmids
often the code for antimicrobial resistance
plasmids
the change in the base sequence of the DNA
mutation
can be caused by chemicals, radiation, or just be sponataneous
mutation
are mutations rare?
yes
all cells have the ability to repair their what? this mechanism is lost with age
dna
the exchange of genes between 2 dna molecules resulting in a new combination of genes in a chromosome
genetic recombination
genetic recombination among microorganisms of the same generation
horizontal gene transfer
binary fission in bacteria (reproduction) is
vertical gene transfer
3 types of horizontal gene transfer are
conjugation, transduction, transformation
conjugation involves 2 cell types:
donors (aka F+) and recipients (aka F-)
the F factor codes for the ___ used in transfer of information from the donor cell
pili
the F factor codes for the pili used in transfer of information from the ?
donor cell
what allows the donor cell to remain alive?
conjugation
requires physical contact between donor and recipient cells (by the pili)
conjugation
a recipient bacterial cell takes up free dead/dying DNA from its environment
transformation
in ____ dna is transferred from one cell to another by means of bacterial viruses called bacteriophages
transduction
in transduction dna is transferred from one cell to another by means of bacterial viruses called
bacteriophages
uses recombinant DNA technology which moves the gene of interest from one genome to another utilizing in vitro recombination of dna molecules
genetic engineering
often used as the cloning vectors to close and transfer genes from one cell to another
plasmids and bacteriophages
there are agricultural, industrial, medical, and environmental applications for
genetic engineering
care is taken to "disable" these genetic modified organisms by engineering metabolic defects into them
...
the first step in a bacteriophage infection of a bacteria
Absorption of the bacteriophage to a cell
the second step in a bacteriophage infection of a bacteria
injection of viral dna into bacteria
the third step in a bacteriophage infection of a bacteria
synthesis of viral proteins
the fourth step in a bacteriophage infection of a bacteria
viral nucleic acid replication
the last step in a bacteriophage infection of a bacteria
release of newly synthesized bacteriophages
the transducing particle is a ___ that occurs when a piece of bacterial DNA is taken up by the newly forming bacteriophage. it can then be used to transfer bacterial dna from one cell to another through the bacteriophage.
mistake
the ___ particle is a "mistake" that occurs when a piece of bacterial DNA is taken up by the newly forming bacteriophage. it can then be used to transfer bacterial dna from one cell to another through the bacteriophage.
transducing
two genera of bacteria may survive unfavorable conditions by undergoing
sporulation
the most closely related group of organisms is called
species
simple components of a prokaryotic cell always include
cytoplasm, cell membrane, ribosomes, cell wall, and chromosomes
thick gelatinous layer
capsule
____ contains enzymes for respiration
cell membrane
capsular bacteria appear
mucoid and shiny
bacteria are mainly characterized by their
cell wall
bacteria with thicker cell walls are gram
positive
thread like extensions on the bacteria made of protein
flagella
contains bacterial DNA
plasmid
a form of sexual reproduction
conjugation
fine hair like structures protruding from bacteria cell wall
pili
an example of a bacterial virulence (ability to produce disease) factor
capsule or plasmid
encapsulated bacteria are more ___ than nonencapsulated bacteria
virulent
what characteristic of a bacterial cell wall helps the bacteria maintain its shape?
peptidoglycan cross linking
change in base sequence of dna
mutation
bacteria reproduce by
binary fission
bacteria that prefer reduced oxygen are called
microaerophiles
bacteria that can only grow in the absence of oxygen are called
obligate anaerobes
bacteria requiring complex organic compounds as a food source
heterotrophs