Final Exam Flashcards
a genome contains?
genetic information in a cell
a genotype is?
the genetic makeup containing potential properties
what is DNA gyrase?
bacteria have a singular circular chromosome, supercoiled and attached to the plasma membrane
ecoli DNA has____ base pairs?
46 million
what is genomics?
sequencing and molecular characterization of genomes
how is supercoiled DNA made?
relaxed circle of dna folded over each other, result in the contact between the helix in two places, dna gyrase action, twisting introduces
what are the 3 stages of molecular information flow?
replication(duplication of dna), transcription (dna participation in protein synthesis through rna) and translation (determination of amino acid sequence)
Dna gyrase activity is inhibited by?
quinolones, fluoroquinolones, novobiocin
Archaea uses _______ gyrase?
reverse
does cellular dna replicate before or after division?
before cell division
what is semiconservative replication?
each new double stranded dna molecule contains one original strand and one new strand
DNA is replicated from the ____ end?
3’
Dna in some bacteria is________?
biderctional
what are the steps to transcription?
- enzymes unwind from double helix
- proteins stabilize the unwound parental dna
- leading stand synthesized continuously by dna polymerase
- lagging strand synthesized discontinuously
- dna polymerase digests rna primer and replaces it with dna
- dna ligase joins the discontinuous fragments of the lagging strand
rapid amplification of Dna in vitro is?
polymerase chain reaction
PCR uses DNA _____?
polymerase
what are used to run through repeated cycles of heating and cooling in the PCR?
thermocyclers
transcription synthesizes _____ from _____?
dna from rna
what are the 3 types of rna used in transcription?
mrna, rrna, trna
what is used in the rna nucleotide instead of thymine?
uracil
what enzyme does transcription use?
rna polymerase
translation includes sense condons that?
code for amino acids
in bacteria what does the start codon AUG code for?
formulmethione
what are nonsense codons?
stop codons that signal the end of protein molecule
during translation what asists the transport of required amino acids during protein synthesis?
trna
why can translation of mrna into proteins begin before transcription is complete in prokaryotes?
since mrna is produced in the cytoplasm
what is repression?
regulatory mechanism that inhibits gene expression and decreases synthesis
what is repression response of?
overabundance of end product mediated by repression proteins
what is induction?
process that turns on transcription of a gene induced by an inducer (ex. lactose metabolism in ecoli)
what is used for the regulation of bacterial gene expression?
operon model of expression
francis jacob and jaques monod are responsible for ?
model for regulation of protein synthesis
what is the main idea of the operon model of suppression?
structured genes are regulated together
what is an operon?
set of operator and promoter sites and structural genes
what is a mutation?
change in the base sequence of dna
a silent mutation is?
may not be affected by actual function of encoded protein
a mutation where a single base is replaced is?
point mutation
a missenese mutation is?
base substitution results in amino acid substitution
a mutation where a stop codon is created is?
nonsense
a mutation where there is deletion insertion to cause a shift is?
frameshift
a spontaneous mutation is?
occurs in the apparent absence of mutation
mutagens are?
environmental agents that directs or indirectly bring out mutations
chemical mutatgens consist of ?
nitrous acid
what creats thymine dimmers during radiation?
uv light
what are light repair enzymes?
photolysases use visible light energy to separate dimer
what is dark repair?
nucleotide excision repair
what is the muattion rate?
probability that a gene will mutate when a cell divides
spontaneous mutation rates are usually high or low?
low
how do mutagens affect the frequency of mutation?
increase the spontaneous rate of mutation usually by 10-1000 times
how is identifying mutations easier in prokaryotes?
effects of mutated gene are not masked by normal versions as in most eukaryotes
what is positive or direct selection?
detection of mutant cells by rejection of unmutated parent cells
what is negative or indirect selection?
indifies cells that cannot preform a certain function
what is an auxotroph?
any mutant microorganism with a nutritional requirement that is absent in the parent
a carcinogen is?
mutagens that cause cancer
what is an ames test?
use bacteria as carcinogen indictaters based on back mutations or reversions
the removal or destruction of all forms of microbial life?
sterilization
commercial sterilization?
limited heat treatment sufficient to destroy spores of clostridium
disinfection is?
control directed at destroying harmful microorganisms
antisepsis is?
disinfection applied to living tissue
mechanical removal is?
degerming
sanitization is?
lowering microbial counts to safe public health levels
bacteriostasis is?
does not kill but stops or stays further growth
asepsis is?
absence of significant contamination
biocide or germicide is?
cide to kill, death occurs at constant rate
what are 3 affects of antimicrobial treatments?
number of microbes, environmental influences, exposure time
alteration of membrane permeability causes?
leaky cells ,lots of cellular contents
heat kills primarily through?
enzyme denaturation
what is thermal death point?
lowest temperature at which microorgansims in a liquid will be killed in 10 minutes
thermal death time?
minimum length of time for all bacteria in a liquid culture to be killed at a certain temperature
decimal reduction time is?
in which 90% of a population of bacteria at a given temp
______ kills microrganisms through coagulation of proteins ?
moist heat
what lowers microbial numbers and eliminates pathogenic microorganisms?
pasteurization
what is hist?
high temperature short time pasteurization
what is filtration used for?
sterilize heat sensitive materials
what bacteria grows slowly at refrigerator temperatures?
pychotrophs
what is desiccation?
viability retained but reproduction and growth ceases
osmotic pressure is used in?
food preservation
what have high electron beams?
gamma rays, x rays
what does the target theory of damage do?
creates sufficient mutations to import lethality
what wavelength has little affect of microorgansims?
microwaves
how many bacteria is the disinfectant solution tested with?
3 bacteria (salmonella cholerasus, staphlococcus aureus, pseudomonos aeruginosa)
what is the disk diffusion method?
disks of filter paper containing agents or antibiotics are placed on an agar plate and monitored for zones of inhibition
what are 6 types of disinfectants?
phenol and phendics, bisphenols, biguanides, halogens, alkohols, heavy metals.
who established the magic bullet theory?
paul enrlich
who first found penicillin?
alexander flemming
how does narrow spectrum differ from broad spectrum?
broad (inhibit gram negative and positive)
narrow (primarily gram positive)
inhibition of cell wall synthesis can react with which subunits?
30s or 50s
disruption of the plasma membrane results in ?
metabolite loss
what inhibits cell wall synthesis?
penicillin, carabaperems
what do semi synthetic penicillins do?
remove and replace side chains from the neutral molecule
what are carabaperems?
class of b-lactam antibiotics
monobactams have ______ toxicity?
low
what time of ring structure do monobactams have and what bacteria do they affect?
single, and affects only gram negative bacteria
what are cephalosporins?
inhibit cell wall structure, resistant to penicillin, affective against gram negative
what inhibits protein synthesis, has a broad spectrum and can be toxi to the host?
chlaramphenicol and aminogycosides
what are tetracyclines?
broad specrum, inhibit protein synthesis, penetrate body tissues, affective against stds
what are macroslides?
contain macrocyclic lactone ring, most affective against strepto cocci
what is polymyxin B ?
effective against gram negative bacteria, injures plasma membrane, used against infections caused by pseudomonas
what inhibits rna synthesis?
rifamycins
what do quinolones do?
selectively inhibit dna gyrase required in dna replication?
what are sulfonamidas?
sulfa drug, among first synthetic drugs to treat microbial disease
what is an antifugal drug?
used against athletes foot, and yeast infections
what are 4 types of drug resistance?
1) destruction or inactivation of the drug
2) prevention
3) altertion of target site
4) rapid efflux
what do nitrogen fixing bacteria do?
fix nitrogen , obligately aerobic, members of alpha or gamma proteobacteria
what are enteric bacteria?
homegenous group of gram negative non spoulating bacteria, facuulatively aerobic
vibrio and photobacterium are?
mostly aquatic and fermentive metabolism
what are rickettsias?
obligate intacellular parasites, significant human pathogens
what are spirillia?
motile and spiral shaped, nitrogen fixers
what are sheathed proteobacteria?
filamentous beta with unique life cycle, formation of flagellated swarmer cells with long tube or sheath
organisms that form varous cytoplasmic extrusions are?
stalked bacteria
what ar gliding myxobacteria?
specialized form of motility, members of delta proteobacteria,
what functions as electron acceptors under anoxic conditions?
sulphate and sulfur
phylum 2 consists of?
gram positive bacteria
phylum 2 is divided into 2 subdivisions which are?
high gc and low gc
low gc gram positive bacteria are ?
sporeformers
what are two characteristics staphlococci?
nonspore, common parasite of humans, found on skin and mucous membranes, produce toxins
what are lacto bacilli?
includes lactic acid bacteria, produces lactic acid as byproduct, grow anaerobically
what are two properties of streptococci?
produce acidic byproducts, classified according to reactions on blood sugar
what are listeria enterococcus?
gram positive cocco bacilli, survives refrigeration temps
what are mycoplasms?
no walls, highly peomorphic, smallest self replicating organisms
what are cryneform bacteria?
rod shaped, irregular cell arrangements, include animal and plant pathogens
what are propiohic acid bacteria?
discovered in swiss cheese, ferment glucose to propiohic acid
what are mycobacterium
distinctive cell wall (acid fast stain), seperated into slow and fast growing groups
what are actinomycetes?
group of filamentous bacteria, soil organisms
phylum 3 consists of?
cyanobacteria, blue green pigment, oxygenic photosynthesis, n fixing cells
what are prochlorophytes?
oxygenic phototrophs containing chlorophyll
what are the assorted phyla ?
chlamydia
spirochates
bacteriodetes
fusobacteria
