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Microbio mini exam
Terms in this set (40)
electrons pass through this area much more easily, and appear white in an electron micrograph
appears as electron opaque region
how is DNA structured in bacterial cells?
covalently closed double stranded circle of DNA
where is DNA associated in bacterial cells?
where is the replicon located in bacterial cells?
haploid or diploid in bacterial cells? why is this?
haploid; only one gene for each phenotypic characteristic
why can bacterial DNA replication occur after the cell has already divided?
bidirectional DNA replication because of the circular structure (can have three replicons in initial strand)
what do shift stains do?
particularly stain DNA
an enzyme that "clips" the supercoiled covalently closed DNA
an enzyme that winds the circular DNA back into a supercoil
gyrase (Topoisomerase II)
are gyrase and Topoisomerase IV located in eukaryotes?
no, uniquely prok
extrachromosomal DNA that contains non-essential genes
what defines a non-essential gene?
a gene that is not involved in replication; may be involved in anti-phagocytic mechanisms, however
what kind of plasmids have their own origins of replication?
what kind of plasmids only replicate when the cell does because they do not have a replicon?
made or altered existing plasmids so we can change existing bacterial cells
have genes involved in pathogenicity
series of genes close together; may find three genes on the plasmid, and each may encode for different things; one might be a toxin
nothing more than plasmids that contain genes that INACTIVATE ANTIBIOTICS and chemotherapeutic agents
resistance factors (R factors)
--- systems can be encoded by R factors
how can R factors be transferred to other bacteria?
endowing recipient with same characteristics as the donor has
part of the R factor that contains genes that encode for resistance
part of the R factor that makes it possible to be transferred
gene that makes the RTF segment able to be transferred
most overworked plasmid there is
what is the function of a ribosome?
translation (protein synthesis)
what is the chemical composition of a ribosome?
prokaryotes have --S and eukaryotes have --S
prok = 70
euk = 80
required nutrients/metabolites synthesized or stored during "times of plenty"
the equivalent of fat or lipids?
PHB (poly B hydroxybutyric acid)
turns red-brown with iodine
turns blue with iodine
called volition or metachromatic granules due to the blue metachromasia observed by light microscopy; polymerized phosphate used in DNA and ATP synthesis
what genera of bacteria produce endospores? (that you know of)
Bacillus cereus (food-poisoning)
Clostridium tetani (tetanus)
Clostridium perfingens (gasgangreen)
Clostridium botulinum (botulism; toxic)
do endospores have a reproductive value for bacterial cells? if not, what are they used for?
no reproductive value, only used for survival from desiccation, radiation, absence of nutrients
where/when are endospores produced?
under threatening environmental conditions as a part of a complex developmental program exhibited by the cell
can endospores last long periods of time?
yes, could be thousands of years
almost totally void of water; Dipicolinic acid is complexed with Ca2+, exhibits a laminated appearance
ultrastructure of an endospore
what is a tennis racket structure of an endospore called?
how long does endospore formation take?
anywhere from 4-8 hours
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