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chapters 9,6,11,12

Microbiology exam #2

Three basic parts of a nucleotide are Phosphate deoxyribose sugar nitrogenous base
The 2 strands of DNA are joined to each other or held together by hydrogen bonding
Which of these are base paired correctly? C-T C-A G-T T-A T-A
The 2 strands of the DBNA molecule are antiparallel
The specific point on the DNA molecule where replication begins is the origin of replication
Early in the process of DNA replication, the enzyme________ separates the 2 strands helicase
DNA polymerase requires a template for the synthesis of DNA can only add nucleotides in a certain direction
If an organism lost the ability to make primase, what would it be unable to do? add a short sequence of complementary RNA to the existing DNA strand
Two different mechanisms for copying the DNA strands are used because the strands are oriented in opposite directions
On one of the strands of bacterial DNA, the new complementary strand is synthesized discontinuously into small pieces of DNA called Okazaki fragments
One bacterial chromosome replicates to become 2 chromosomes with each made of one strand of DNA from the original chromosome and one newly synthesized strand
A segment of DNA encoding a protein or an RNA molecule is a gene
A __________ is the physical expression of the genes present and can change depending upon what genes are turned "on" phenotype
Which nitrogenous base is NOT present in RNA Thymine
Both DNA and RNA are usually double stranded molecules FALSE
The process of synthesizing RNA from a DNA template is _____ transcription
The initial transfer RNA occupies the _____ on the ribosome P site
_________ are groups of 3 bases in mRNA that specify one amino acid in the amino acid chain Codons
If the codon GGU is positioned in the A site of the ribosome, what will occur? a tRNA with the anticodon CCA will deliver its amino acid to the site
What usually terminates the process of translation presence of a stop codon on mRNA
The bond connecting amino acids is a _________ bond peptide
If you know the sequence of nucleotides in mRNA, you can deduce the DNA sequence it was transcribed from True
What depicts the direction genetic info flows? DNA--->RNA--->protein
Protein synthesis occurs on ribosomes
Replication, transcription and translation take place in the bacterial cytoplasm True
RNA is a chain of nucleotides
What three components make up RNA structure? phosphate, nitrogenous base, ribose sugar
What component of RNA is different from one individual or one bacterium to the next? order of nitrogenous bases
The purpose of RNA synthesis is to provide a new copy of DNA as the original strand deteriorates over time False
Transcription begins when RNA polymerase binds to __________ promoter on DNA
If one strand of DNA contains the bases ACAGT, what would be the complementary bases on the mRNA strand UGUCA
Synthesis of mRNA is in the 5' to 3' direction with new nucleotides being added to the 3' end of mRNA molecule
What happens when a hairpin loop forms in mRNA? the RNA polymerase and the mRNA dissociate from the DNA
The process of transcription is similar to the synthesis of the leading strand during DNA replication
After mRNA is made, what generally occurs? the mRNA is translated to protein
Unlike DNA, RNA is usually single-stranded. True
The classic transformation experiment done by Griffith used harmless and virulent strains of Streptococcus pneumoniae
Transformation is a form of recombination. Recombination is__________ one bacterium donating DNA to another
In addition to transformation, the other 2 forms of horizontal gene transfer or recombination are conjugation and transduction
In the beginning of transformation ________ binds to the target cell double stranded DNA
During the entry of the donor DNA into the recipient cell one strand is broken down by nucleases
The donor DNA pairs with a homologous region o the recipient DNA
Mismatch repair is activated by any difference between nucleotide sequence in the donor and recipient DNAs
As a result of mismatch repair during transformation cells may have either original DNA or donor DNA in them
During the process of transformation in the lab setting, cells are plated on selective media to make sure that only transformants grow
Cells that are capable of bringing DNA from their environment in through their cell wall are called competent
Transformation is facilitated by proteins on the cell wall that bind DNA from the environment
Central Dogma (newer version) While information primarily flows from DNA to RNA to protein, some info from RNA flows back to DNA in a regulatory role
An operon is composed of ________ DNA
All structural genes in an operon code for proteins related to the same function TRUE
Which part(s) of an operon will eventually be translated to protein? Structural genes
If lactose is present, the operator of the lac operon is switched ____________ therefore, this is an example of a(n) ______operon. on, inducible
Of all infectious agents, which group has the most variety of drugs designed to treat infections? Bacteria
Antibiotics would be effective against which of these infections? Cholera genital warts whooping cough syphillis
Why do antiviral medications often have side effects? Viruses are intracellular pathogens, and therefore there is often host cell damage with antiviral treatments.
Rather than developing more antiviral medications, what is a more common focus for researchers when it comes to viral diseases? vaccine development
virus size large to small E. coli streptococcus Rickettsia Mimivirus Rabies Adenovirus Yellow fever
multiplication cycle of RNA animal viruses Adsorption penetration-virus engulfed into vesicle uncoating-viral envelope is shedded synthesis assembly release
unique characteristics of viruses -while viruses are not considered living, they cannot direct own multiplication but can direct the behavior of living cells -have a nucleic acid genome, can be RNA or DNA, SS or DS -species-specific and infect cells from all 5 kingdoms
During replication of the positive sense strand of lytic RNA phage, in order to make more positive -the + RNA strand must code for the synthesis of RNA polymerase -RNA replicase uses the + sense RNA as a template to make -strand RNA -the - sense strand RNA is used to make more + strands
The negative sense strand of RNA is_____ used to synthesize more + strands
A positive sense strand lytic RNA phage attaches to the cell wall of an E. coli bacterium False
Phage induced lysozyme lyses the host cell releasing the newly made phage True
A positive strand of RNA can directly act as mRNA
Steps to the lytic cycle adsorption penetration synthesis assembly Lysis
How are temperate phages replicated? The phage is replicated along the host cell's genome
An infection in animals similar to a lysogeny in bacteria is called a ___________ infection. persistent
The activation of a prophage to enter the lytic cycle is called _________. induction
Both lytic and lysogenic cycles eventually lead to bacterial host cell damage True
How does lysogeny affect humans Bacteria can become virulent due to phage genes, causing greater damage to infected human host
Possible configurations of viral nucleic acids single stranded DNA Double stranded DNA-linear double stranded DNA-circular
Microbial control methods-Physical heat and radiation
microbial control methods-mechanical filtration
microbial control methods-chemical surfactants halogens- ex: chlorine ---> which is sporicidal H2O2---> high activity-sporicidal phenolics--->ex: carbolic acid alcohols heavy metals-->ex: silver---> which is oligodynamic-sm amounts
halogens Chlorine Iodine- ex: betadine, penetrates cells and interferes w/protein synthesis, can also be extremely irritating to the skin and toxic when absorbed
Hydrogen peroxide -3% solution is used as an antiseptic for skin and wound cleansing -can be sporicidal in high concentrations -highly toxic to cells because of free radical formation
ethylene oxide used to disinfect delicate instruments and plastic materials
Phenolics Triclosan is a member of this antimicrobial category
Chlorhexidine -used in hand scrubs, prepping skin for surgery -targets cellular membranes and denatures proteins -popular hospital agent due to low toxicity and rapid action -limited variable effects on fungi and viruses
aldehydes VERY TOXIC, but used to disinfect surgical instruments
alcohol -a 70% solution is best for denaturing microbial proteins -evaporates quickly which lowers effectiveness -ex: ethyl and isopropyl -dissolves membrane lipids and decreases surface tension
detergents disrupt cell membranes but only rated for low level disinfection
heavy metals mercury and silver
The effectiveness of a particular microbial agent is governed by several factors besides _____ time
The _______ of microbes affects the action of an agent, as does _______ of the population. Number composition
The ________ as well as the ______ level of the environment will also influence the action of microcidal agents temperature pH
The __________ of the agent as well as the _______________ against microbes also play a role in its ability inactivate microbes concentration mode of action
the presence of ________ matter, such as saliva and blood also inhibits the action of many microbicidal agents organic
relative resistance of different microbial types from more to less Protons bacterial endospores mycobacterium staphylococcus and pseudomonas protozoan cysts protozoan trophozoites most gram - bacteria fungi and fungal spores non enveloped viruses most gram + bacteris enveloped viruses
The use of radiation as a microbial control mechanism -use of rad. to control microbial growth comes in 2 form ionizing and nonionizing. ionizing is most destructive -nonionizing rad, ex UV light causes electrons to mk a quantum leap to orbital w/ higher energy state, cause thymine dimers to form, no ions
destruction of ALL microbial life Sterilization
destruction of most microbial life on inanimate surfaces disinfection
destruction of most microbial life on living tissue antisepsis
mechanical removal of most microbes from living or inanimate surfaces decontamination
A chemical labeled as bactericidal will kill bacteria where as a chemical labeled as bacteriostatic will inhibit bacterial growth but will not kill them true
Conjugation donor-living cell w/f factor recipient- living F-cell direct 2 cells transfer DNA through hollow appendages
transformation donor- Lysed cell recipient- living competent cell indirect naked DNA is taken up through cell boundary
transduction donor-dead cell lysed by phage recipient-living cell infected with phage indirect but with a vector Bacteriophage transfers DNA between host cells
agents that will kill a microbial pathogen or completely inactivate its ability to cause disease virucide germicide sporicide
betadine belongs to what group of chemical control agents halogens
major cellular target of chemical antiseptics and disinfectants cell wall synthesis of proteins and nucleic acids cytoplasmic membrane cytoskeleton is NOT
sterile saline has sterilizing effects on the skin false
DRY heat control of microbes more time is required -incineration ---> temps can reach 6000 degrees C -oven----> sterilization takes 4 hours
MOIST heat control of microbes less time required -non-pressured steam -boiling water---> disinfection---baby bottles and food -pasteurization--->beverages----71.6 C for 15 seconds -steam under pressure--->15 psi--- sterilizes on least time
Salting of meat prior to the development of refrigeration technology was an example of using osmotic pressure to control microbial spoilage of this food product true
mechanism of drug resistance drug inactivation--> drug is changed decreased permeability--> drug can't ding its target drug pumps---> drug enters but doesn't stay alternate metabolic pathway---> drug binds correctly
Inhibition of virus entry no infection
Inhibition of nucleic acid synthesis no viral DNA synthesis no reverse transcription
Inhibition of viral assembly/release no virions leave host cell
The goal of antimicrobial therapy is to deliver a drug that will destroy the _______ without harming the _______ pathogen host
An ideal antimicrobial drug is _________ rather than ____________ and is relatively soluble. microbicidal microbiostatic
An ideal drug remains potent long enough to act, but does not lead to the development of ____________ in microbial populations. antimicrobial resistance
An effective drug assists the host's ______ and should not cause ______ or other infections. defenses allergies
An ideal drug should be readily delivered to the site of _________ in the host and overall the drug should be reasonably ________. infection priced
methods of antimicrobial susceptibility testing that can be used to determine minimal inhibitory concentration (MIC) Etest Tube dilution test
Antibiotics other than Beta-lactam drugs, that also inhibit bacterial cell wall synthesis vancomycin Isoniazid Bacitracin
Viruses are able to multiply inside a non-living cell False
Individual viral particles have only one type of nucleic acid True
Cells that lack compatible virus receptors are resistant to infection by that virus True
What is the function of the reverse transcriptase enzyme synthesizes DNA from RNA
superinfection occurs due to the overgrowth of other potentially pathogenic microbes during or after initial antimicrobial therapy
drugs that are designed against which target are likely to have the least selectivetoxicity cell membrane
antimicrobial that has the broadest spectrum of activity tetracycline
your microbiome is most susceptible to changes when taking a _______ spectrum antimicrobial broad
Which microbial group is the easiest to selectively target with antimicrobials bacteria
BAsed on Kirby Bauer testing, a microbe is susceptible to antibiotic X and Y. X has Therapeutic Index 10 and Y Index of 3. Which would be the best choice based on the info given? Antibiotic X
Created by: vtlove116