Kral Microbio, Exam 3 MEGASET (Pearson, all three practic exams)

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What is the initial effect of ionizing radiation on a cell?

It causes the formation of highly reactive ions.

What are the methods by which genetic change can occur in bacteria?

Conjugation - sex in bacteria where genetic material know as a fertility factor is transferred from F+ male to F- female.

Transformation - process where a recipient cell takes up donor DNA and acquires new genetic traits. Recipient is always alive, but donor can be alive or dead.

Transduction - transfer of DNA from one cell to another from a virus/infective phage DNA.

Mutation - a change in the DNA base sequence, which can be spontaneous, induced, or silent (change in genotype but not phenotype).

What is transformation in the context of bacteria?

The transfer of DNA from a donor to a recipient cell as naked DNA in solution.

What does biotechnology involve?

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 an advantage of using E. coli to make a human gene product?

Its genes are well known.

What do restriction enzymes do?

They function as bacterial enzymes that destroy phage DNA.

What is the most accurate term for an agent used to reduce the number of bacteria on a toilet?

Disinfectant.

Define the following:

Sterilant

Virucide

Fungicide

Germicide

Bacteriostatic

sterilant - destroys all living microorganisms

virucide - inactivates viruses

fungicide — kills yeasts and molds

germicide - kills microbes

bacteriostatic - inhibits the growth of bacteria, DOESNT kill vegetative bacterial cells

Which statement regarding antimicrobial control agents is FALSE?

Most chemical agents can achieve sterility.

How long can the most resistant bacterial endospores withstand boiling?

Up to 20 hours.

What can be used to sterilize nutrient agar at home without an autoclave?

Pressure cooker at 121°C for 15 minutes.

What method preserves beef jerky from microbial growth?

Desiccation.

Which of the following is NOT a method of food preservation?

Microwaves.

What can sterilize plastic Petri plates in a plastic wrapper?

Gamma radiation.

Which treatment controls microbial growth most effectively?

They are equivalent treatments. WHICH TREATMENT CONTROLS

How does freezing preserve food?

By slowing the metabolic processes of foodborne microbes.

What is a limitation of the autoclave?

It cannot be used with heat-labile materials.

Which method does NOT achieve sterilization?

Pasteurization.

What is the best method to sterilize heat-labile solutions?

Membrane filtration.

What is ethylene oxide?

A sterilizing agent.

What results in lethal damage to nucleic acids?

Heat, radiation, and some chemicals.

What concentration of ethanol is the most effective bactericide?

70 percent.

Which statement regarding Florey and Chain is mismatched?

Florey and Chain - developed penicillin as a distributable drug based on Fleming’s discovery

Ehrlich - "magic bullet" theory

Fleming - initial identification of penicillin's effect on gram-positive microbial growth

Kirby and Bauer - disc-diffusion method

What percentage of antibiotics are produced by bacteria?

More than half.

What are most available antimicrobial agents effective against?

Bacteria.

What happens to a cell in the presence of penicillin?

It undergoes lysis.

Which of the following does NOT affect eukaryotic cells?

Semisynthetic penicillins.

Which organism would MOST likely be sensitive to natural penicillin?

Streptococcus pyogenes.

What type of drug is griseofulvin?

A drug that inhibits mitosis and is more effective against fungi.

What causes drug resistance?

When antibiotics are used indiscriminately.

Which statement about drug resistance is FALSE?

It is found only in gram-negative bacteria.

What can result from washing regularly with antibacterial agents?

Increased susceptibility to disease due to removal of normal microbiota.

What is the major significance of Robert Koch's work?

Microorganisms cause disease.

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

RNA polymerase

In the figure, if base 4 is adenenine, what is base 11’? (remember complimentary configuration)

Adenine

In the figure, if base 4 is adenine, what is base 4’?

Thymine

What are the products of transcription? What is not?

Products: RNA, mRNA, tRNA, and rRNA.

Not a product: a new strand of DNA

DNA is constructed of:

two strands of nucleotides running in an antiparallel configuration.

A gene is defined as:

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

When ultraviolet light strikes DNA, it can cause a specific type of damage, best described as:

Thymine bases on one strand, next to each other, are covalently linked together to form a thymine dimer. This dimer distorts the DNA structure, leading to replication errors.

The enzyme that is responsible for synthesizing RNA is:

Transcriptase

Which of the following is due to a mistake in packaging of DNA

Transduction, which is the process by which DNA is transferred from one bacterium to another VIA a virus.

Chemicals in cigarette smoke that selectively cause cells with a mutation to replicate more than cells without a mutation are called

Promoters

Restriction enzymes are important because they

Generate overlapping sticky ends on DNA

A method of one-way gene transfer that requires cell-to-cell contact is

Conjugation

Which are not Methods of Sterilization

Pasteurization and lyophilization

Endospores have resistance to some levels of ionizing radiation because they are

Desiccated

If you were asked to sterilize a heat-sensitive item (and not cause damage to the item), which of the following would be most suitable

Ethylene oxide (carboxide)

Membrane filtration

Does not necessarily remove viruses

Major targets for disinfectant action include

Cell proteins and cell membranes

The most practical and efficient method of physical control is

Heat

Which term refers to a chemical that is used at safe levels in accordance with public health requirements

Sanitizer

The chemical that is the active ingredient in Lysol is

Cresol

The difference between an antiseptic and a disinfectant is

Antiseptics are typically used to kill bacteria on living surfaces, while disinfectants are used to kill bacteria on nonliving surfaces.

Criteria for usefulness of an antimicrobial agent does NOT include

Destruction of normal flora

A chemical that is not used much anymore because it is carcinogenic is

Formaldehyde

The most famous antibiotic, the first one discovered, one that inhibits bacterial cell wall synthesis, is

Penicillin

An example of a chemically-synthesized chemotherapeutic agent is

Sulfonamide

An antibiotic (by definition)

Is a chemical agent that is the product of some organism’s metabolism

For a non-growing (stationary-phase) bacterial culture, which should be most effective as an antimicrobial agent

Polymyxin B

What is the drug of choice to treat anthrax

Cipro

Measures to minimize drug resistance include

Discriminate use, drug dose high and combination of drugs

Conceivably, the most common mechanism of microbial resistance is

Alteration of target molecule

Many cases of the flu on a college campus would be referred to as a(n)

Epidemic

Which of the following is a factor in the development of disease

Number of pathogens, vector, ability to flourish outside the body

Cholera, a very serious disease in many areas of the world, is normally transmitted via the

Gastrointestinal tract

An example of a disease normally transmitted via the blood is

Hepatitis

A disease organism that is present in high numbers in a specific geographical location is referred to as a(n)

Endemic

Which organism requires fimbriae to stick to the lining of the genitourinary tract

E. coli

What has been shown to remain active and infectious for hours on a toilet seat

Herpes Virus

Which of the following diseases requires a tick vector for transmission

Rocky Mountain Spotted Fever

A gene in a living organism is best defined as

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

DNA is constructed of

Two strands of nucleotides running antiparallel.

Which of the following is not a product of transcription?

Single strand of DNA.

Thymine dimers can be caused by

Ultraviolet radiation.

The Genetic Code is made up of bases in

mRNA.

DNA directly participates in

Replication and transcription.

Genetics and metabolism are tied together by the fact that

The genes code for enzymes that catalyze reactions that result in characteristics.

A silent mutation is

Always a change in base sequence and sometimes a change in amino acid sequence.

Smoking cigarettes has been shown to be responsible for all of the following EXCEPT

Smoking cigarettes has been shown to be responsible for all of the above.

A key discovery that contributed to the development of genetic engineering was

Restriction enzymes.

Genetic engineering very often uses what to move hybrid plasmids into cells?

Transformation.

Cigarette smoke contains what?

Cigarette smoke contains chemical mutagenic agents.

Ultraviolet light is considered?

A physical mutagenic agent.

Restriction enzymes are important because they

Generate overlapping sticky ends on DNA.

Genetic modification procedures can be used to

All of the above.

An autoclave is:

A machine that utilizes moist heat under pressure to achieve sterilization of equipment and supplies.

Membrane filtration

Is a method of sterilization.

Lyophilization

Is a method of preservation.

A common method for sterilizing laboratory glassware is

Dry heat (oven).

Adding salt to ham or sugar to canned fruit is an example of what type of control?

Osmotic pressure.

The major effect of using ionizing radiation on living organisms is

The production of hydroxyl radicals from the water.

Which is not a method of sterilization?

Ultraviolet radiation.

Factors that normally affect disinfection include

Time, temperature, concentration, surrounding medium.

One of the best disinfectants to use for a biological spill is

Bleach.

If you were asked to sterilize a heat-sensitive item (and not cause damage to the item), which of the following would be most suitable?

Ethylene oxide (carboxide).

Which of the following is FALSE?

Isopropyl alcohol is used to sterilize the skin.

The difference between an antiseptic and a disinfectant is

Antiseptics are normally used on the skin.

A chemical that would be used to inhibit, but not necessarily kill fungi, would be called

Fungistatic.

An example of a mild antiseptic is

Hydrogen peroxide.