Micro Lecture Test #2

An enzyme that copies DNA to make a molecule of RNA is

RNA polymerase

which of the following makes mRNA from the information stored in a DNA template?

RNA polymerase

What is the function of the connector proteins?

They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.

Which step of binary fission is the reason for genetically identical daughter cells?

Replication of the bacterial chromosome

What is the basic function of the lac operon?

To code for enzymes involved in catabolizing lactose.

In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?

To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene

Which of the following best describes the purpose of primers in PCR?

To provide a structure from which DNA can be synthesized

What is unique about transduction compared to normal bacteriophage infection?

Transduction transfers DNA from the chromosome of one cell to another.

Which of the following is an example of horizontal gene transfer in bacteria?

Transduction, conjugation, and transformation

What is the hallmark of all horizontal gene transfers?

Transfer of DNA between organisms of the same generation

Which of the following amino acids is coded by only one codon?

Trp

Agar is used as a solidifying agent in microbiological media since few bacteria can degrade it. T/F

True

Agars can be used to select for growth of certain types of bacteria and then allow for you to identify the different bacteria that can grow on the plate. These agars may be considered both selective and differential. T/F

True

Autoclaving is the most effective method of moist heat sterilization. T/F

True

Bacterial growth refers to an increase in the numbers of cells in a bacterial culture. T/F

True

Filtration methods, followed by growth of the bacteria trapped on the filters in growth media, are used to count bacteria present in very low concentrations, such as in lakes and streams. T/F

True

In recombinant DNA technology, a vector is a self-replicating segment of DNA, such as a plasmid or viral genome.

True

In the Ames test, any colonies that form on the control should be the result of spontaneous mutations. T/F

True

Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases. T/F

True

Moist heat destroys organisms by denaturing proteins. T/F

True

Mutations that are harmful to cells occur more frequently than those that benefit cells. T/F

True

Nitrogen-fixing bacteria, such as cyanobacteria, can use atmospheric nitrogen (N2) for their nitrogen source. T/F

True

One of the first commercial successes of recombinant DNA technology was the production of human insulin using genetically engineered E. coli. T/F

True

Open-reading frames are segments of DNA in which both start and stop codons are found. T/F

True

Pseudomonas has been found growing in quaternary ammonium compounds (quats). T/F

True

Recombination will always alter a cell's genotype. T/F

True

Some antimicrobial chemicals are considered to be disinfectants and antiseptics. T/F

True

Turbidity is an indirect measurement of bacterial growth that can be measured using a spectrophotometer. T/F

True

What are the products of semiconservative replication for a double-stranded DNA molecule?

Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.

What results when a single bacterium reproduces?

Two genetically identical daughter cells

Self-replicating DNA used to transmit a gene from one organism to another is a

Vector

A restriction fragment is

a segment of DNA.

A gene is best defined as

a sequence of nucleotides in DNA that codes for a functional product.

All of the following substances are used to preserve foods EXCEPT

biguanides.

Patients with indwelling catheters (long-term tubes inserted into body orifices for drainage, such as through the urethra and into the urinary bladder) are susceptible to infections because

biofilms develop on catheters.

Which of the following disinfectants acts by disrupting the plasma membrane?

bisphenols

Pathogenic bacteria isolated from the respiratory or intestinal tracts of humans are

capnophiles that grow best in carbon dioxide incubators.

The mechanism by which the presence of glucose inhibits the lac operon is

catabolite repression.

An enzyme produced in response to the presence of a substrate is called a(n)

inducible enzyme.

Repair of damaged DNA, in some instances and mechanisms, might be viewed as a race between an endonuclease and

methylase

Which of the following techniques is NOT used to introduce recombinant DNA into plants?

microinjection

If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?

pressure cooker at 121°C for 15 minutes

The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by

snRNPs

Which of the following is involved in bringing amino acids to the ribosomes?

tRNA

RNA polymerase is guided by the

template strand of DNA

If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?

the primary structure of the protein

When the cell is not in the presence of lactose,

the repressor proteins bind to the operator.

Assume you inoculated 100 cells, with a generation time of 20 minutes, into 100 ml of nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient broth. After incubation for 4 hours, you can reasonably expect to have

the same number of cells in both.

Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes

use codons to determine polypeptide sequences.

Biotechnology involves the

use of microorganisms to make desired products, the use of animal cells to make vaccines, and the development of disease-resistant crop plants.

What is Mesophile?

A bacterium that is a common cause of human infections but is also part of our microflora would have to be in the mesophile class of bacteria.

What is psychrophile?

A bacterium with increased cholesterol in its cytoplasmic membrane to maintain membrane fluidity at extremely low temperatures would probably fall in the psychrophile class of bacteria.

What kind of bond is formed when two amino acids join together?

A peptide bond

What results from the process of translation?

A polypeptide

What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A?

A stop codon would be introduced prematurely.

The Pap test for cervical cancer involves microscopic examination of cervical cells for cancerous cells. A new, rapid diagnostic test to detect human papilloma virus (HPV) DNA before cancer develops is done without microscopic exam. The steps involved in this FastHPV test are listed below. What is the second step?

Add an RNA probe for HPV DNA.

Which statement regarding agricultural biotechnology is FALSE?

Agricultural biotechnology is extremely limited because foreign genes cannot be inserted into plant cells.

Which of the following regarding antimicrobial control agents is FALSE?

Alcohols effectively inactivate nonenveloped viruses by attacking lipids.

Assume that you have an antimicrobial agent specific for each of the targets listed below. Indicate which type of microbe would be most susceptible to the agent by placing it in the appropriate bin.

All bacteria = glycolytic enzymes & membrane proteins Gram + = Peptidoglycan Gram - = blank Viruses = envelope proteins All bact. & proteins = nucleic acids

The restriction enzyme EcoRI recognizes the sequence GAATTC. Which of the following is TRUE of DNA after it is treated with EcoRI?

All of the DNA fragments will have single-stranded regions ending in AA.

What is the inducer molecule in the lac operon?

Allolactose

A chemostat is continuous culture system that is designed to promote and prolong exponential growth and prevent bacteria from entering stationary phase. How might this work?

Chemostats provide a continued source of fresh nutrients and remove wastes and dead bacterial cells.

Bacteria naturally prefer company instead of solitude for growth. Examples of this kind of communal growth pattern can be found everywhere, from surfaces of the teeth and the intestines, to the surface of a slimy rock in the lake, to the thick floc that clogs water pipes. These examples of communal bacterial growth are known by what name?

Biofilm

All of the following are effective for destroying prions EXCEPT

Boiling

The addition of which of the following to a culture medium will neutralize acids?

Buffers

The anticodon for valine is

CAA

What type of reactions are these? 1) Glucose is broken down into two pyruvates. 2) Starches are digested into individual glucose molecules.

Catabolic

Which enzyme catalyzes the reaction: 2H2O2 → 2H2O + O2?

Catalase

Which of the following is a method of vertical gene transmission?

Cell division

Which of the following best describes why a vector is used in genetic modification procedures?

Cells usually won't copy an isolated gene sequence.

A population of cells carrying a desired plasmid is called a

Clone

In performing a ten-fold dilutions series from a sample containing 10,000 bacteria per milliliter, the fourth tube in the dilution series will have 10 cells per milliliter. T/F

False

Microorganisms placed in high concentrations of salts and sugars undergo lysis. T/F

False

Most pathogenic bacteria are thermophiles. T/F

False

Some cells may contain multiple genomes. T/F

False

The miRNAs in a cell inhibit protein synthesis by forming complementary bonds with rRNA. T/F

False

The pH of the medium has no effect on the activity of the disinfectant being applied.

False

The practice of breeding plants and animals for desirable traits, such as high crop yield, is called natural selection. T/F

False

The term biotechnology refers exclusively to the use of genetically engineered organisms for the production of desired products. T/F

False

Ultraviolet light (UV) causes irreversible breaks in DNA strands. T/F

False

Where would one find an uncharged tRNA molecule in a ribosome?

In the P and E sites

How would one increase the concentration of a particular polypeptide in a cell?

Increase the level of transcription

Why would a recombinant DNA molecule be inserted into a host cell?

It can be copied, transcribed, and translated into a desired protein.

Which of the following is a limitation of the autoclave?

It cannot be used with heat-labile materials.

Which of the following statements about recombinant DNA technology is FALSE?

It has limited application because genes of interest cannot be moved from one type of cell to another.

Which of the following statements regarding a bacterium that is R+ is FALSE?

It is F+.

In which direction does the replication fork move?

It moves ahead of the newly synthesized DNA.

What is the function of the parental DNA in replication?

It serves as the template for DNA replication.

Which of the following is an advantage of using E. coli to make a human gene product?

Its genes are well known

An advantage of cDNA over genomic DNA is that it

Lack introns

Which of the following are terms associated with Okazaki fragments?

Lagging strand, DNA ligase, and discontinuous

Which DNA strand is synthesized continuously?

Leading strand

What is considered to be the average natural mutation rate that occurs during DNA replication?

One in every billion nucleotides replicated.

How frequently do silent mutations occur?

One out of every three mutations

Which of the following are used to silence specific genes and hold promise for treating cancer or viral diseases, such as hepatitis B?

RNA interference (RNAi)

Genetic change in bacteria can be brought about by

-transformation. -transduction. -mutation.

The study of genetic material taken directly from the environment is

metagenomics.

A culture medium consisting of agar, peptone, and beef heart is a

complex medium.

Gluteraldehydes are among the most effective chemical control agents because they __________.

considered a relatively safe sterilizing agent

Cell-to-cell contact is required for transduction to occur. T/F

False

Desiccation is a reliable form of sterilization. T/F

False

During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants are true?

-Disinfection can occur by physical or chemical means. -Endospores and viruses can resist disinfectant treatment. -Disinfectants are used to inhibit or destroy pathogens.

After a period of rapid growth (log phase), bacterial growth rates will slow and enter the stationary phase. The number of viable cells no longer increases, but instead stays constant. In this activity you will indicate the statements that correctly describe what is happening during stationary phase.

-Harmful waste products may be accumulating. -The number of cells that are dying is balanced by the number of new cells that are being formed. -The cells are likely running out of nutrients.

The Lake of the Ozarks is a human-made lake, so it collects runoff from coal strip-mining, fertilizers, resort wastewaters, and septic drainages. The average lake temperature is between 10∘C and 21∘C. Consider the physical requirements for growth and multiplication that would allow fecal coliforms to "blossom" in the Lake of the Ozarks. Which of the following would accurately describe these organisms?

-Mesophiles -Facultative halophiles -Psychrophiles

Salts and sugars work to preserve foods by creating a

Hypertonic Environment

In addition to physical requirements, bacterial growth and multiplication also entails chemical requirements. Which of the following statements would accurately describe chemical requirements and conditions associated with growth in the Lake of the Ozarks environment?

-The lake environment will support the growth of facultative anaerobes -Fecal coliforms will need to acquire trace elements for growth in the lake environment. -Fecal coliforms will likely contain enzymes to counteract toxic oxygen forms.

Which of the following places the steps in the PCR procedure in the correct order? 1) Incubate at 94°C to denature DNA strands; 2) Incubate at 72°C for DNA synthesis; 3) Incubate at 60°C for primer hybridization.

1,3,2

What is considered Thermophile?

1. A bacterium that can be found growing in a hot spring 2. The thermophile bacteria have evolved to grow and excel in temperatures that denature most protein and kill most organisms.

Isolation and Cultivation of the Bacteria.. What is considered differential?

1. An agar that allows for the distinction of bacteria based on metabolism 2.Aspect of MacConkey agar allows for the determination of which bacteria are lactose fermenters and which are not. 3. EMB agar uses lactose and two dyes that allow it to be differential between the blue-black colonies of E. coli and the pinkish colonies of all other enteric bacteria. 4. A blood agar plate contains sheep red blood cells and allows for the determination of hemolytic capabilities for all bacteria that grow on the agar. 5. If an agar contains a dye or pH indicator in the presence of a sugar, it is generally considered differential for those bacteria that may ferment the sugar over those that cannot.

Isolation and Cultivation of the Bacteria.. What is considered Selective?

1. An agar that uses the dye in crystal violet agar suppresses the growth of Gram-positive bacteria. This agar would be considered selective. 2. An agar that uses a high salt concentration to limit the growth of one type of bacteria over another would be considered selective. 3. Bile salts in MacConkey agar allow for the agar to be selective for the growth of enteric Gram-negative bacteria over Gram-positive bacteria.

Which of the following treatments is the most effective for controlling microbial growth?

140°C for 4 seconds

A broth medium has been inoculated, and microbial numbers will be counted periodically to generate a bacterial growth curve. At 2 hours after inoculation, the culture has progressed through lag phase and is now in log phase. At this point, the population size is 1 million cells. The generation time is 30 minutes. Assuming the continuation of log growth, how many cells would there be at 2 hours of growth in log phase?

16 million

Starting with three cells, how many cells would result from three rounds of replication?

24

Which of the following pairs is mismatched? 1) Ag wound dressings 2) H2O2 open wounds 3) alcohols open wounds 4) organic acids food preservation 5) CuSO4 algicide

3

A microbe reproduces by binary fission every 20 minutes under favorable conditions. If you started with one cell, how long would 10 generations take and how many bacteria would be present if all the conditions were just right?

3 hours 20 minutes, producing 1,024 bacteria

Refer to the table. If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, what is the order of bases in the sense strand of DNA?

3' AGACGTTTCAAT

Put the following steps of bacterial replication in the correct order, starting from a parent cell. 1) Cell elongation 2) Septum formation 3) Chromosome replication 4) Separation of daughter cells

3,1,2,4

Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many cells were in the original sample?

36 per milliliter

Most fungi grow best at pH

5

Which of the following pairs of terms is mismatched? 1) sterilant destroys all living microorganisms 2) virucide inactivates viruses 3) germicide kills microbes 4) fungicide kills yeasts and molds 5) bacteriostatic kills vegetative bacterial cells

5

During elongation, how is the RNA synthesized?

5' to 3'

Ribosomes move along the mRNA in which direction?

5' to 3'

How many codons code for the amino acid arginine?

6

The following steps must be performed to make a bacterium produce human protein X. 1-Translation 2-Restriction enzyme 3-Prokaryotic transcription 4-DNA ligase 5-Transformation 6-Eukaryotic transcription 7-Reverse transcription Which of the following places the steps in the correct order?

6, 7, 2, 4, 5, 3, 1

Most bacteria grow best at pH

7

Which concentration of ethanol is the most effective bactericide?

70%

You have a small gene that you wish replicated by PCR. After 3 replication cycles, how many double-stranded DNA molecules do you have?

8

Why is DNA replication essential for a cell?

An organism must copy its DNA to pass genetic information to its offspring.

What type of reactions are these? 1) Four amino acids are linked together to form a tetrapeptide. 2) A uracil base is added to an mRNA strand by RNA polymerase. 3) Ribose and inorganic phosphate are bonded to form a nucleotide base. 4) Ammonia is added to glutamate to form glutamine.

Anabolic

The biosafety level (BSL) for most introductory microbiology laboratories is

BSL-1

Which biosafety level (BSL) is appropriate for handling organisms that present a moderate risk of infection?

BSL-2

The biosafety level (BSL) for a clinical microbiology laboratory working with potentially airborne pathogens, such as tuberculosis bacteria, is

BSL-3

How is bacterial translation different from eukaryotic translation?

Bacteria can begin translation before transcription has terminated

Which of the following best describes how recombinant DNA technology currently helps patients who do NOT produce adequate amounts of growth hormone (hGH)—a condition that otherwise leads to stunted growth?

Bacteria now produce hGH.

Most bacteria reproduce by

Binary Fission

Which of the following are used by the Centers for Disease Control and Prevention to track outbreaks of foodborne disease?

DNA fingerprints, restriction fragment length polymorphisms, and reverse-transcriptase PCR(rtPCR)

Which enzyme breaks the hydrogen bonds during replication?

DNA helicase

What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands?

DNA is flexible.

An enzyme that makes covalent bonds between Okazaki fragments is

DNA ligase

Which of the following attaches the target gene to a desired location?

DNA ligase

The following are steps used to make DNA fingerprints. What is the third step?

Digest with a restriction enzyme.

Which of the following is NOT a step in bacterial cell division?

Disappearance of nuclear envelope

Bacteria typically contain multiple chromosomes. T/F

False

If you begin with six cells, how many cells would you have after three rounds of division?

Forty-eight cells

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?

Freezing

How is generalized transduction different from specialized transduction?

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

the start codon also codes for which amino acid?

Methionine

All of the following are methods of food preservation EXCEPT

Microwaves

Which of the following best describes why microbial death curves are typically plotted logarithmically?

Most of the cell death occurs early in the treatment.

How long does it take for the daughter cells to initiate or start the next round of replication?

No time is required -- they are ready to divide immediately after DNA replication and separation of the daughter cells is complete if conditions are right.

All of the following factors contribute to hospital-acquired infections EXCEPT

None of the answers is correct; all of these factors may contribute to hospital-acquired infection.

During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome?

P site

Why is PCR a valuable technique?

PCR creates large amounts of DNA from minute source quantities.

Which of the following methods would be most appropriate for gathering data to plot a bacterial growth curve throughout the four phases?

Plate count

Recombinant DNA techniques typically involve generating a clone. Why?

Producing a clone generates many copies of the gene of interest.

What ensures that the single strands of DNA do not come back together?

Stabilizing proteins

What does a thermocycler do?

Subjects samples to temperature changes

How does the ribosome know if the entering charged tRNA is correct?

The anticodon on the tRNA base pairs to the codon on the mRNA.

When bacteria are inoculated into a new sterile nutrient broth, their numbers don't begin to increase immediately. Instead, there is a lag phase that may last for an hour or even several days. Why don't bacterial numbers increase immediately?

The bacteria must adjust to the nutrient content in the new medium, synthesizing necessary amino acids, growth factors, and enzymes.

Contaminated hospital equipment represents a difficult environment to control harmful microbial growth. Regarding influences that affect disinfection of hospital equipment, which of the following is an accurate statement?

The cell walls of gram-negative bacteria are especially resistant to many chemicals that are used destroy microbes.

What enables the copied chromosomes to separate during binary fission?

The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes.

Why is the DNA synthesis of the lagging strand considered discontinuous?

The synthesis is moving in the opposite direction from the replication fork.

With which genetic region does the repressor protein interact?

The operator region

What would happen if the septum did not form during binary fission?

The parent cell would now have two copies of the chromosome

According to the animation, to what genetic element does the RNA polymerase bind?

The promoter

What is the initial target of RNA polymerase?

The promoter

Which of the following statements regarding infections involving biofilms is FALSE?

There is no way to prevent biofilms from developing on surfaces.

Which statement best describes restriction enzymes?

They are important for cloning applications because they can be used to cut DNA at specific nucleotide sequences.

How do stabilizing proteins work on the DNA?

They bind to the single-stranded DNA.

How do restriction enzymes cut DNA sequences?

They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.

How is translation terminated?

When a protein called a release factor enters and binds to the A site

Why is baker's yeast useful for expressing genetically engineered genes?

Yeast cells are eukaryotic and so would likely be successful in expressing eukaryotic genes.

Which of the following best describes a clone in the context of genetic modification procedures?

a culture of genetically identical cells

In the Southern blot technique, which of the following is NOT required?

addition of heat-stable DNA polymerase to amplify DNA

In PCR, it is important to use Taq DNA polymerase, as opposed to other DNA polymerases. This is because Taq is capable of synthesizing DNA _________.

after exposure to 94∘C

All of the following substances are effective against nonenveloped viruses EXCEPT

alcohol

The miRNAs in a cell

allow different cells to produce different proteins.

Transformation is the transfer of DNA from a donor to a recipient cell

as naked DNA in solution.

GAU codes for

aspartic acid.

Which of the following substances is used for surgical hand scrubs?

chlorhexidine

A transducing phage

contains fragments of the host chromosome instead of the viral genome.

Synthesis of a repressible enzyme is stopped by the

corepressor-repressor complex binding to the operator.

The damage caused by ultraviolet radiation is

cut out and replaced.

The preservation of beef jerky from microbial growth relies on which method of microbial control?

desiccation

A colleague has used computer modeling to design an improved enzyme. To produce this enzyme, the next step is to

determine the nucleotide sequence for the improved enzyme.

Which of the following is an advantage of the standard plate count?

determines the number of viable cells

The use of an antibiotic-resistance gene on a plasmid used in genetic engineering makes

direct selection possible.

The term aerotolerant anaerobe refers to an organism that

does not use oxygen but tolerates it.

Sampling lake water for microscopic organisms is not as easy as it sounds when you want to both count and identify species. In a given water sample, your bacteria of choice can be rare or difficult to culture, particularly given the mixture of bacteria in a biofilm. Which of the following culture media would be best for growing fecal coliforms when they are relatively less abundant than other bacteria in the lake?

enrichment culture medium

Bacteria that can grow in the presence or absence of oxygen (O2) are called __________.

facultative anaerobes

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?

facultative halophiles

Cultures of the Lake of the Ozarks water samples were grown on enrichment media for identification. However, these organisms are present to some degree in all samples. An important question from a clinical perspective is whether or not there is a significant increase in the fecal coliform populations that would put people's health at risk. If you were part of the team investigating this outbreak, how would you best enumerate the fecal coliform threat?

filtration count culture

Which of the following methods used to count microbes is correctly identified as direct or indirect?

filtration--direct method

A base insertion or deletion in the translated region of the gene may lead to

frameshift mutation.

Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?

gamma radiation

The random shotgun method is used in

genome sequencing.

Which of the following is an example of a metabolic activity that could be used to measure microbial growth?

glucose consumption

Oxidizing agents include all of the following EXCEPT

glutaraldehyde.

Which one of the following is most resistant to chemical biocides?

gram-negative bacteria

Surface-active agents act by decreasing surface tension so that microbes can be more easily removed. All of the following agents use this mechanism of action EXCEPT __________.

halogens

Which of the following results in lethal damage to nucleic acids?

heat, radiation, and some chemicals

Which of the following enzymes unwinds the two strands of DNA so that they can be copied during replication?

helicase

Which of the following is NOT a direct method to measure microbial growth?

metabolic activity

An advantage of synthetic DNA over genomic or cDNA is the ability to

insert desired restriction sites into the DNA sequence.

If you have inserted a gene in the Ti plasmid, the next step in genetic engineering is

inserting the Ti plasmid into Agrobacterium.

An iodophor is a(n)

iodine mixed with a surfactant

A recombinant cell

is a cell that receives DNA from an outside source and incorporates it into its own.

Ethylene oxide

is a sterilizing agent.

Which of the following phases of the bacterial growth curve is matched with the correct definition?

log phase--the phase in which organisms are actively dividing and the generation time is constant

Which of the following can be translated into protein?

mRNA

Transcription produces which of the following?

mRNA, tRNA, and rRNA are all produced by transcription.

A base substitution that changes a codon coding for an amino acid to a stop codon is called a

nonsense mutation.

Which of the following does NOT achieve sterilization?

pasteurization

The source of nutrients in nutrient agar is

peptone and beef extract.

Disinfection of water is achieved by all of the following EXCEPT

peracetic acid.

Which enzyme catalyzes the reaction: H2O2 + 2H+ → 2H2O?

peroxidase

Which of the following elements is NOT correctly matched with its cellular function?

phosphorus used for production of carbohydrates.

Ribosomes contain which of the following?

rRNA

Which of the following is an advantage of the direct microscopic count?

requires no incubation time

Consider a culture medium on which only gram-positive organisms such as Staphylococcus aureus colonies can grow due to an elevated NaCl level. A yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the pH as a result and changing the color of a pH indicator chemical. This type of medium would be referred to as a(n)

selective and differential medium.

A mutation that affects the genotype of the organism but not the phenotype is called a

silent mutation.

RNA that has hydrogen bonded to itself forms a

stem loop.

According to the operon model, for the synthesis of an inducible enzyme to occur, the

substrate must bind to the repressor.

Bone and tendons for transplant are decontaminated by

supercritical fluids.

Which enzyme catalyzes the reaction: O2- + O2- + 2H+ → H2O2 + O2?

superoxide dismutase

When a transducing phage interacts with a new host cell,

the DNA from the previous host can recombine with the new host chromosome.

PCR can be used to identify an unknown bacterium because

the RNA primer is specific.

The initial effect of ionizing radiation on a cell is that it causes

the formation of highly reactive ions.

The antimicrobial activity of chlorine is due to which of the following?

the formation of hypochlorous acid

Which of the following is the best definition of generation time?

the length of time needed for a cell to divide

Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched?

thermophile growth at 37°C

The following is true of quarternary ammonium compounds EXCEPT

they are effective when combined with soaps.

Conjugation differs from reproduction because conjugation

transfers DNA horizontally, to nearby cells without those cells undergoing replication.

An enzyme that catalyzes the cutting and resealing of DNA, and is translated from insertion sequences, is

transposase

DNA is constructed of

two strands of nucleotides running in an antiparallel configuration.

Which of the following pairs is mismatched? 1) ozone takes electrons from substances 2) ultraviolet radiation desiccation 3) supercritical fluids CO2 4) plasma sterilization free radicals 5) ionizing radiation hydroxyl radicals

ultraviolet radiation desiccation

Which of the following is an organic growth factor?

vitamin B1