Microbiology Exam 2

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The base sequence of a messenger RNA molecule that is complementary to the sequence CGTTAGA would be expressed as:

GCAAUCU

How do you sterilize toxoid preparation for immunization

Gamma rays

Sometimes called "the clap"

Gonorrhea

A biological safety cabinet usually filters the air with a __________ filter

HEPA

The principal effect of ultraviolet light on bacterial cells takes place:

in the DNA of the cell

A period of 2 hours at 160°C is required for the destruction of bacterial spores:

in the hot-air oven

Heavy metals generally kill microorganisms by

inactivating enzymes and structural proteins

The spectrum of activity of tetracycline antibiotics

includes Rickettsia and Chlamydia

Bacteriocins are proteins that:

inhibit or kill other bacteria.

Chloramphenicol is a broad-spectrum antibiotic that:

interferes with peptide bond formation in microorganisms.

Cephalosporins act by:

interfering with cell wall synthesis.

The halogen common to Wescodyne and Betadine:

is iodine in a form known as iodophor

A substance that has been pasteurized

is not necessarily sterile.

Point mutations:

it affects a base pair. it may be a change to a different base pair. it may be a substituted base pair

All the following are true of the bacterial chromosome, except:

it contains the plasmids

Filtration is very different from heat or radiation methods because:

it is a physical separation method rather than a sterilization method

An antibiotic is useful in

killing environmental competitors

AKA Hansen disease

leprosy

All the following are essential to the process of DNA replication, except

mRNA

The most common filtration method uses the

membrane filter

Mercury is rarely used in antiseptics in the modern era because

mercury is very toxic to body tissues

Sulfonamides can interfere with the ______ of bacteria because they are similar to _____.

metabolism, PABA

All of the following are true about DNA repair mechanisms, except

mismatch repair involves replacing long sequences of DNA.

A phenol coefficient (PC) higher than 1 indicates a chemical is:

more effective than phenol.

Tetracyclines such as doxycycline are currently the drugs of choice for treating:

most rickettsial and chlamydial diseases

Besides HGT, __________ is another way to permanently alter the genetic material in a bacterial cell.

mutation

Isoniazid inhibits the production of

mycolic acid

The stop codon in an mRNA codes for

no amino acid

The tRNA anticodon TTT would pair up with the codon

no such anticodon exists

How many origins of replication are there in every bacterial DNA molecule?

one

Tetracycline antibiotics are associated with

discoloration of the teeth

Triclosan destroys bacteria by

disrupting cell membranes.

All the following function in the process of protein synthesis, except

electron transport

Clinically important antibiotics in the macrolide group are:

erythromycin and clarithromycin.

A person who is allergic to penicillin may be treated with

erythromycin, but not ampicillin

Chaperones are proteins that

facilitate proper folding of polypeptides

plasmids contain over 50% of the total genetic information of a bacterial cell

false

Bacterial polypeptides will start with the amino acid

formylmethionine (fmet).

Energy wavelengths less than 1 nm are associated with

gamma radiation

Penicillin antibiotics are used primarily against

gram positive bacteria

The aminoglycoside drugs like gentamicin are widely prescribed for treatment of:

gram-negative bacterial infections.

The major side effects of therapy with chloramphenicol include:

gray syndrome

One of the Streptococcus pneumoniae strains used by Griffith was called smooth because the cells

had a smooth capsule

A bacterial cell that is transduced

has acquired bacterial DNA from a virus

Pasteurizing milk for 30 minutes at 63°C is called the __________ method.

holding (batch)

Genetic recombination that involves the lateral intercellular transfer of DNA from a donor cell to a recipient cell is called

horizontal gene transfer (HGT).

The tubercle bacillus is usually susceptible to

rifampin, but not penicillin.

F factors replicate the DNA using the

rolling circle mechanism

Antibiotics are an example of a

secondary metabolite

Antibiotics represent compounds not directly used for growth and reproduction called:

secondary metabolites.

A new DNA molecule can be produced by

semiconservative replication

______ is a condition in which microbes or their toxins are present in tissues or the blood.

sepsis

One drop of 1% solution used to prevent gonorrhea in newborns

silver nitrate

One of the limitations of the autoclave is that:

some plasticware melts in the high heat.

The origin of the penicillin-resistant strain Neisseria gonorrhoeae probably is due to:

spontaneous mutation

Mutations arising from chance events in the environment are known as

spontaneous mutations

Messenger RNA contain

start and stop codons

___________ refers to the destruction of all forms of microbial life

sterilization

In the operon, genes that code for proteins are called:

structural genes

Side effects attributed to tetracycline antibiotics include:

stunted bones and discolored teeth.

Antimicrobial agents designed and developed in the research laboratory are called

synthetic drugs

children affected with this STD can develop Hutchinson's triad

syphilis

forms a gumma

syphilis

The effects of Hutchinson's triad, a possible complication of congenital syphilis, are observed in the

teeth, eyes and ears

Ultraviolet light is valuable for reducing the microbial population in:

the air of a hospital room

The chemotherapeutic index refers to a drug's:

toxic and therapeutic doses.

If boiling water is used to destroy microorganisms, it is imperative that

traces of organic matter be removed

The production of RNA using DNA as a template is known as:

transcription

Requires the intervention of a virus.

transduction

DNA from the environment enters a recipient cell.

transformation

May follow a release of DNA fragments from a dead cell

transformation

Was first observed in pneumococci by Griffith

transformation

Isoniazid is a narrow-spectrum antibiotic that is useful for treatment of:

tuberculosis

The passing of genes from parent cells to daughter cells is called

vertical gene transfer

Chlorhexidine is a phenol derivative used to

wash hands and clean wounds superficially

When food has been salted

water diffuses out of microorganisms, causing them to shrivel.

An antibiotic that affects Staphylococcus, Escherichia, and the mycobacteria would be considered a drug:

with a broad spectrum

All of the following apply to phenol

-Its activity is reduced in the presence of organic matter. -Joseph Lister first used it in the 1860s. -It is the standard disinfectant against which others are evaluated

If an mRNA sequence is AUGGCCGACUGA, then the inactive DNA strand sequence must be:

ATGGCCGACTGA

Which of the following is not part of chain termination during translation?

AUG codon

Can induce human tumors and is highly explosive

Ethylene oxide

Used in the sterilization of plastics

Ethylene oxide

Which chemical would be a sterilization method for plasticware that cannot be heated?

Ethylene oxide gas

a conjugation pilus is produced by

F+ cells

Intermittent sterilization is done at ___________ for __________ minutes for __________ successive days.

100ºC; 30; 3

In an autoclave under 15 lb/in2 steam pressure, the approximate temperature will be

121.5°C

If a complete bacterial mRNA contains 3,000 codons, how many amino acids will exist in the protein produced?

2,999

The mRNA that codes for a particular protein will have ___ nucleotide(s) for each amino acid in the protein

3

The conditions necessary to kill Mycobacterium tuberculosis by pasteurization are:

30 minutes at 63°C.

How many genes are in Escherichia coli?

4,300

Example of base analog

5-bromouracil

One of the difficulties in controlling the spread of gonorrhea is that

50% of female infections may be asymptomatic.

HEPA filters prevent which percentage of particles from escaping as aerosols into the laboratory air?

99%

Both bacitracin and polymyxin B are synthesized by _____. They are quite toxic internally and can cause kidney damage. Therefore, they generally are restricted to topical use, such as on the skin.

Bacillus species

How can a 1.5-mm long, circular chromosome fit into a 1.0- to 2.0-µm E. coli cell?

By supercoiling, a twisting and tight packing Packing caused by nucleoid-associated proteins DNA double helix twists on itself like a wound-up rubber band

This STD is called soft chancre

Chancroid

Bacteriocin

Chemical produced by bacteria that kill other bacteria

______ is a very small mycoplasma that causes urethritis. It can be treated by azithromycin.

Chlamydia trachomatis

The less-common STD caused by Chlamydia trachomatis

Chlamydial urethritis

Tissues samples contain reticulate bodies

Chlamydial urethritis

Which chemical agent burns skin and eyes on contact?

Chlorine dioxide

Plasmid

Closed circular DNA, with few genes, nonessential to the cell

plasmids are composed of

DNA

enzymes involved with excision repair in DNA

DNA ligase DNA polymerase Nucleases

The enzyme responsible for the synthesis of DNA from a DNA template is called

DNA polymerase

The quinolones are synthetic drugs that block _______ and are used to treat urinary tract infections, gonorrhea and chlamydia, and intestinal tract infections.

DNA synthesis

How are antiseptics and disinfectants different?

Disinfectants are used on objects, whereas antiseptics are used on living tissues.

DNA ligase

Enzyme that seals DNA fragments together

Why is the genetic code considered redundant?

In most cases, there is more than one codon for each amino acid.

A halogen often used as a tincture for wounds

Iodine

What does an F plasmid do

It allows for the transfer of genetic material from a donor to recipient cell through a recombination process.

During transcription, how many DNA strands in a gene are transcribed?

One strand

Armes test

Procedure to screen chemicals for mutagenic properties

Which one of the following bacteria is not related to a sexually transmitted disease?

Pseudomonas aeruginosa

What are resistance factors known as?

R plasmids

UGA, UAG, and UAA are what type of codons?

Stop codons

Mutagen

Substance that induces change in DNA bases

Which of the following does not apply to plasmids?

They are essential for growth

What is an insertion sequence (IS)?

a small segment of DNA with about 1,000 base pairs

Which of the following types of RNA function to bring the amino acids to the ribosome for assembly into a polypeptide chain?

Transfer RNA

Prokaryote genome studies have shown that genes involved with the same process are clustered. This makes genetic control more efficient because their activity can be coordinated within one cluster.

True

Watson and Crick worked out the structure of DNA using Rosalind Franklin's X-ray crystallography.

True

Base pair insertion

Type of mutation that produces a reading frameshift

Another method, known as the __________ method, uses a temperature of ___________ for 3 seconds.

UHT; 140ºC

Radiations with wavelengths between 100 nm and 400 nm are considered:

UV light

Nonionizing radiations are typified by:

UV rays

How do you sterilize a table top in a laboratory?

Ultraviolet light

_______ has emerged as a key treatment in therapy for gram-positive organisms that are resistant to other antibiotics; it is often is referred to as the "drug of last resort

Vancomycin

The similarities between organisms and symptoms have led many microbiologists to believe there is a relationship between:

Yaws and syphilis

The deletion or insertion of nucleotides during chromosomal replication most likely would cause

a "reading frameshift" mutation

Mutation

a change in DNA base sequence

Trachoma or chlamydial opthalamia is

a disease of the eye causing blindness in 7 to 9 million people worldwide.

Which of the following could not be sterilized by the autoclave?

a laboratory table

What happens in semiconservative DNA replication?

a new strand of DNA with bases complementary to a parent strand combines with a parent strand to form the double helix.

Sterilization by intermittent sterilization requires:

a period of 3 days

Both the cephalosporin and penicillin antibiotics:

act on the cell wall of bacteria.

HEPA filters are used to filter which one of the following

air

Copper has its principal activity against

algae

The two major drawbacks to the use of natural penicillins are:

allergic reactions and development of drug-resistant bacteria.

Detergents display their antimicrobial ability by:

altering the cell membrane and causing cell lysis.

Genes existing on plasmids may include those for:

antibiotic resistance

Gonorrhea caused by which of the following has recently been observed?

antibiotic-resistant strains

The hot-air, or oven, method of sterilization is useful for those items that:

are dry or do not mix with water.

Sulfanilamide is highly active against those bacteria that:

are gram-positive

A common feature of bacitracin and polymyxin B is that both antibiotics

are only used topically.

All aminoglycoside antibiotics function by:

attaching to bacterial ribosomes and causing a misreading of the genetic code.

A(n) __________ is a high-pressure device in which steam is superheated under pressure to kill microbes in about 15 minutes

autoclave

An advantage of the membrane filter is that:

bacteria multiply and form colonies on its surface, where they can be studied

Ethyl alcohol has virtually no effect on:

bacterial spores

A plasmid may carry information for

bacteriocin synthesis. transfer of genetic material. antibiotic resistance.

Low temperature is

bacteriostatic

Termination factors:

bind to the mRNA site at the ribosome.

Ultraviolet light may induce a mutation by

binding together adjacent thymine molecules on the DNA molecule.

Salpingitis, a possible complication of gonorrhea, is observed as a(n)

blockage of fallopian tubes

Tetracycline antibiotics are a ________ spectrum antibiotic

broad

How do transposable genetic elements cause mutations?

by interrupting the coding sequence in genes, thereby often resulting in no protein being produced.

Characteristics of gonorrhea bacteria

diplococcus, small cell, gram negative, nonmotile

Transposons are movable genetic elements that

carry information such as antibiotic resistance from one gene location to another

Nitrous acid

chemical mutagen

Gray syndrome sometimes occurs in newborns as a serious side effect of _______.

chloramphenicol therapy

Can be used to disinfect municipal water supplies and swimming pools

chlorine

Which of the following elements would be classified as a halogen?

chlorine

Griffith's experiments used species of

coccus

Iodophors are

complexes of iodine and detergents that release iodine over long periods of time.

Deafness; impaired vision; and notched, peg-shaped teeth are a result of

congenital syphilis

Commonly involves F factor transfer.

conjugation

F factor transfer converts the recipient to F+.

conjugation

Involves DNA replication by the rolling circle method

conjugation

Requires contact between donor and recipient cells.

conjugation

involves an hfr cell

conjugation

Hfr cells are involved in

conjugation with F- cells

Nitrous acid can cause a chemical mutation by

converting DNA's adenine to hypoxanthine.

For UV light to kill microorganisms

direct exposure must take place

A method of preserving food that depends upon osmosis is

dehydration

Moist heat kills microorganisms by:

denaturation

The organism that causes gonorrhea

dies quickly and is rarely contracted from a dry surface such as toilet seat.

Parts of the operon

operator structural genes promoter

When food is dehydrated through salting, the process of water loss is called

osmosis

Pseudomembranous colitis is a condition of the intestine that may be related to:

overuse of lincomycin and clindamycin.

__________ is used to remove pathogens from milk and dairy products.

pasteurization

One drawback to the use of ultraviolet light as a sterilizing agent is its failure to

penetrate liquids or solids

The beta-lactam nucleus is the basic structure of:

penicillin

Beta-lactamase converts _____ to ______, which has no effect on the bacterial cell wall.

penicillin to penicilloic acid

Some bacteria produce beta-lactamases, which break down and inactivate

penicillins

Penicillins interfere with the synthesis of

peptidoglycan

Gonorrhea under some circumstances can spread to the

pharynx

The F factor in a bacterium is actually a

plasmid

The string of ribosomes all translating the same mRNA is called a:

polyribosome

Silver nitrate was used to

prevent gonorrhea in the eyes of newborns.

Sulfonamide is a competitive inhibitor that interferes with the ability of a bacterium to:

produce folic acid

The major activity of transcription is to

produce mRNA molecules

Members of the genus Streptomyces

produce many well-known antibiotics

Which group of antibiotics blocks DNA synthesis in bacteria?

quinolones

Gonococcal proctitis is an inflammation of the

rectum

Using a prevacuum stage in the autoclaving process can effectively

reduce the time to achieve sterilization

phages lyse bacterial cells by

replicating within them

Okazaki fragments form during

replication of the bacterial chromosome

Tetracycline antibiotics are used for

rickettsial and chlamydial diseases

Which of the following is the most efficient method for sterilization of a bacteriological loop?

the direct flame

What type of genetic information is needed in IS?

the genetic information for enzyme transposase, which is needed to move the IS to a new location in a DNA molecule.

In the microwave oven, the energy of microwaves is converted to:

the heat of friction

All the following apply to the process of protein synthesis, except

the mRNA sequence is the same as that on the DNA template strand.

Before alcohol is used for disinfection purposes:

the object to be treated must be carefully cleaned.

The pasteurization method using 140°C for 3 seconds is called:

the ultra high temperature (UHT) method.

The lowest temperature at which a microorganism is killed in 10 minutes is called the:

thermal death point

__________ is the minimum amount of time required to kill microorganisms at a given temperature.

thermal death time

This type of radiation induces adjacent __________ nucleotides in DNA molecules to bind to one another, forming dimers.

thymine

One environmental mutagen is ultraviolet (UV) light. It exerts its mutagenic effect by forming a(n) __________ in the DNA

thymine dimer

Gonococcal symptoms in a male

tingling sensation in the penis, painful urination, discharge of a yellow, thick fluid


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