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Microbiology exam #2

Chapters 9,6,11,12

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
Bacteria have as much genetic information as Eukaryotes False
PLasmids are necessary for the metabolism of bacteria False
What are the main types of plasmids? Why are they medically relevant? F plasmids transferred through F pilus R plasmid for resistance important for antibiotic resistance
DNA replication in prokaryotes is bidirectional, whereas in eukaryotes it is not True
Bacteria have _____ origin of DNA replication, whereas eukaryotes have ________ 1 multiple (bubbles)
What enzyme uses complimentary binding to replicate DNA? RNA? Polymerase
Making mRNA from DNA template is called _________ whereas using tRNA, and ribosomes to make mRNA into a chain of amino acids is called _______ transcription translation
Prokaryotic mRNA is _________, meaning that many genes are transcribed and translated at once. polycistronic
Bacteria utilize alternative splicing in their cells to create alternative versions of proteins. False
Every species on earth essentially uses the same genetic code for codon ----> amino acid pairing True
Bacterial transcription and translation is more efficient than in eukaryotes Don't want interruption of our cells
Antibiotics that interrupt bacterial protein synthesis can also affect eukaryotic cells False, can make multiple transcriptions
What are the three important features of an operon? promoter operator structural genes
What event triggers induction of the lac operon? lactose
The presence of tryptophan represses the trp operon True
Describe the difference between an inducible and a repressible operon inducible is turned on repressible is turned off
What is the difference between positive and negative regulation? positive is controlled by an activation and negative is controlled by a repressor
What are the three ways that bacteria horizontally share genes? Bacterial transformation bacterial transduction bacterial conjugation
What is the difference between F factor transfer and Hfr transfer? F-pilus complete genome oilus Hf is interrupted before DNA transfer
A cell must be ________ in order to be transformed. competent
A bacterium is considered a recombinant if it has new genes, even if they aren't expressed False
__________ are involved in transduction. Bacterial phages
___________ transduction involved the transfer of one specific gene, not a random one. specialized
What is a pathogenecity island? stretch of genes that pass on to be pathogenic
A spontaneous mutation arises from exposure to chemicals or physical agents True
A ______________ mutation results in a stop codon and a nonfunctional protein. nonsense
Mutations are always harmful to organisms False
Mutations, once they happen are permanent True
On an evolutionary scale, why are mutations and genetic diversity important? mutations are changes to an organism's DNA and are important driver of diversity in populations mutation has introduce a new allele into the population that increase genetic variation and may be passed on to the next generation
Viruses can be seen with a light microscope False
Viruses are alive False
Viruses have no internal ______________, and are instead simply infectious particles that contain, at minimum, __________ and ______ metabolic process nucleic acid proteins
Viral infections are more common than bacterial infections True
Viral mutation rates are low and viruses are easy to track in a population False
Viral capsids are constructed from ________ subunits capsomers
What shapes do capsids come in? complex helical isocahedral
List 3 forms of viral nucleic acid dsDNA ssRNA ssDNA
What is an envelope? surrounds the capsid and is part of the membrane
Standard virus classification systems use the following: genetic makeup structure disease caused
A virus name ending in -viridae denotes a viral family
List and describe the main steps of animal virus replication adsorption penetration uncoding synthesis assembly release
What is the difference between DNA virus replication and RNA virus replication? RNA is in cytoplasm and DNA has to be transcribed
Viruses that infect animal cells can never infect human cells False
Describe the main difference between the lytic and lysogenic phase of viral replication Lytic destroys cell Lysogenic stays dormant and can be turned on to the lytic stage
The term plaques is only used to describe the effects of bacteriophage on cell cultures False-all viruses produce plaques
What is a prion? -common feature of spongiform encephalopathies -distinct protein fibrils deposited in brain tissue of affected animals
____________ is disinfection on a living surface antisepsis
Which should be more "harsh" or work better: antisepsis or sanitization? antisepsis
order of most resistant to least resistant endospores mycobacteria protozoan cysts fungal spores gram + bacteria enveloped viruses
Describe the difference between a bactericidal agent and a bacteriostatic agent bactericidal means killing of bacteria bacteriostatic means limiting the growth of bacteria
List and describe four factors that affect microbial death rate number of bacteria population type of microbial growth temp and pH
What are the four cellular targets of physical and chemical agents cell wall cell membrane cellular processes proteins
Lower temperatures can be used with dry heat than moist heat False
The lowest temp required to kill all of the microbes in a sample in 10 minutes is the _________________ thermal death point
Cold merely retards the growth of most microbes. True
Filtration is not a method of sterilization. False
Ultraviolet radiation produces _______ dimers that affect growth by causing ________ pyrimidine absorption
Osmotic pressure achieves sterilization. T/F False
Describe 4 desirable qualities of a germicide. -rapid action in low concentration -solubility in water or alcohol and long term stability -penetration of inanimate surfaces to sustain a cumulative or persistent action -broad spectrum microbial action without toxicity to human and animal tissues
Describe 3 factors that affect the actions of a germicide number of microbes how contaminated is it time of exposure
The most extensively used of all chlorine compounds is _________ Bleach
Phenol is still extensively used as a disinfectant False
A higher concentration of alcohol is more effective than a lower concentration True
List 2 acids used in food preservation lactic acid ascorbic acid
Describe 4 characteristics of an ideal antimicrobial drug not toxic to the host microbicidal not resistant potent long enough to effectively work and not broken down
The _________ test shows antimicrobial susceptibility using large agar plates, a bacterial lawn, and antibiotic-infused discs. Kirby Bauer
Each species of bacteria has the same susceptibility to a particular drug False
Identification of the species of bacteria in an infection is necessary to accurately determine antibiotic susceptibility. True
An antibiotic with a therapeutic index of 4 is less toxic than one with a therapeutic index of 40 False
Microbial susceptibility is the only factor in choosing the right drug. False
Describe some adverse reactions to antimicrobials. allergic reaction diarrhea nausea/vomitting
The ____________ account for the greatest number of drug allergies. Penicillin
Overgrowth of certain microbes due to antibiotic therapy that cause infection is known as __________. Superinfection
The type of drug that inhibits cell wall synthesis is a _________ drug. Describe how it works. Beta-Latam inhibition of cell wall synthesis and target the penicillin binding proteins
An antibiotic that acts on the bacterial cell wall will have little effect on a human cell. True
Describe some ways that protein synthesis inhibitors might work -incorrect amino acid insertion -block movement of RNA -attack one or both subcomponents of the 70s, 50s, or 30s ribosomes
An antibiotic that acts on the bacterial ribosome will have no effect on a human cell. False
The least selectively toxic antibiotics are ones that target the cell wall and folic acid synthesis
Antifungal and antihelminthic drugs can be toxic to human cells True
What are some targets of antifungal? membrane function tubal formation
Generally, how do anti-protozoan and anti-helminth drugs work? inhibit function of the microtubules
There are as many antiviral drugs as there are antibiotics? False
What are three ways can we target viruses? barring penetration blocking transcription preventing maturation
What are some ways we can selectively target HIV replication? reverse transcriptase
Bacteria can be resistant to antibiotics without ever encountering the drug True
List and describe the 5 mechanisms of antibiotic resistance -new enzymes are synthesized -permeability or uptake of the drug into a bacterium is decreased -drug is immediately eliminated -binding sites for drug are decreased in number -an affected metabolic pathway is shut down
What are the current drugs of last resort?
What is a superbug? a strain of bacteria that has become resistant to antibiotic drugs
Many antibiotics prescribed to humans are for viral infections . True
Nearly 80% of all antibiotics in the U.S. are given to ____________ livestock
___________ are a novel treatment that have been used to target specific bacteria and effectively treat bacterial infections. Phages
Created by: vtlove116
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