Micro Bio Exam 2

______ is the normal three-dimensional configuration of a protein that allows proper function

native state

the destruction of all microbial life

sterilization

destroys most microbial life, reducing contamination on inanimate surfaces

disinfection

the same as disinfection , but on a living surface

antisepsis (degermation)

the mechanical removal of most microbes from an animate or inanimate surface

decontamination (sanitation)

What is the goal of sterilization?

destruction of endospores

What are the cellular targets of physical and chemical antimicrobial agents

the cell wall, cell membrane, DNA, RNA, and proteins

_________ are polar molecules with hydrophilic and hydrophobic regions.

surfactants

They bind to the lipid layer and penetrate the internal hydrophobic region of membranes, which open up leaky spots that allow injurious chemicals that seep into the cell and important ions to leak out

surfactants

What is the process that disrupts proteins which render them nonfunctional and breaks the bonds that maintain the secondary and tertiary structure

Denature

______ is the most widely used method of microbial control

heat

moist heat causes _____ damage

irreversible

Examples of moist heat

hot water, boiling water, and steam

______ operates at lower temperatures and shorter exposure times

moist heat

Using _____ ‘s has a microbial effect that coagulates and denatures proteins to permanently halt microbial metabloism

moist heat

________ is air with a low moister content that has been heated by a flame or electric heating coil

dry heat

dry heat ______ cells burning them to ashes

oxidizes

Most of the time cold treatment causes

a halt in activités

dehydration of vegetative cells directly exposed to normal room air

desiccation

The process in which a combination of freezing and drying typically to preserve microbes in a viable state

lyophlization

Energy emitted from atomic activities and dispersed at high velocity through matter or space

radiation

Examples of radiation suitable for microbial control

gamma rays, X raus, and Ultraviolet radiation

Bombardment of microbes with radiation (mainly on surfaces)

irradiation

What type of radiation causes the most damage

ionizing radiation

Type of radiation that ejects orbital electrons from an atom, causing ions to form

ionizing radiation

Type of radiation that excites atoms arising them to higher energy state

non ionizing radiation

UV radiation can form

pyrimidine dimers

______ are abnormal linkages between adjacent pyrimidines which can interfere with DNA replication and transcription that leads to inhibition of growth and death

pyrimidine dimers

What are some examples of halogens

florine, bromine, chlorine, and iodine

Placing organisms at 4\*C is ______.

bacteriostatic

The alcohol wipe used on a patient's skin before an injection is an example of

antisepsis

Each of the following is a target of antimicrobial agents except

cytoplasm

The use of chemical agents directly on exposed body surfaces to destroy or inhibit vegetative pathogens is

antisepsis

Antimicrobial agents can target the cell wall by _______.

digesting it, denaturing proteins, and blocking synthesis

Cold temperatures are considered microbistatic, whereas excessive heat is considered microbicidal. This is due to the fact that 

\
in cold temperatures, the energy of activation is not sufficient to drive chemical reactions regardless of the presence of enzymes, whereas excessive heat denatures enzymes and/or incinerates the cell causing irreparable damage

Some microbial control agents are able to _____ cell proteins by breaking bonds that maintain the native state, the three-dimensional configuration of the proteins

denature

The use of a physical or chemical process to destroy vegetative pathogens on inanimate objects is

sterilization

Which of the following is a disadvantage of dry heat methods such as using a Bunsen burner to incinerate microbes from an inoculating loop and the use of a hot air oven?

\
\
Bunsen burners take too long to sterilize and hot air ovens are hazardous for the operators.

_____ is a control method that removes microorganisms rather than inhibiting or killing them.

filtration

Which of the following is true regarding the use of osmotic pressure as an antimicrobial agent?

Exposing a microbe to a hypertonic environment draws water out of the cell, causing plasmolysis.

Pasteurization ______

reduces the number of vegetative forms

What instrument is most effective for pressure-temperature sterilization?

Autoclave

The process that destroys or removes all microorganisms and microbial forms, including bacterial endospores, on inanimate objects is

sterilization

Surfactants work by

disrupting membrane integrity

When considering time and temperature as factors in microbicidal activity, _______.

\
they are inversely proportional to each other

The easiest microbial forms to kill or inhibit are

vegetative bacteria and fungi

true or false: Bacteriostatic agents kill bacterial cells.

false

True or False: Ionizing radiation is more effective than nonionizing radiation in killing or inactivating microbes.

true

true or false: Isopropyl alcohol wiped across a skin site can sterilize it.

false

True or False: Pasteurization does not inactivate endospores or thermoduric microbes.

true

True or False: Pasteurization is used to sterilize milk.

false

True or False: Prions require more extensive methods of sterilization than are needed for bacterial endospores.

true

True or False: Soaps and detergents are very effective as sterilants.

false

True or False: Chlorine and ethylene oxide are sterilizing gases

true

What is the gaol of antimicrobial chemotherapy?

administer a drug to an infected person that destroys the infective agent without harming the host’s cells

Antibiotics are common metabolic products of ____ __and__ ____

bacterial

fungi

Kirby-Bauer method

 determines the sensitivity or resistance of pathogenic bacteria to various antimicrobial compounds shown on a plate by zones of inhibitions

_________ is the smallest concentration (highest dilution) of drug that visibly inhibits growth

minimum inhibitory concentration

minimum inhibitory concentration is useful in determining ___________________________________ .

the smallest effective dosage of a drug

When was the age of antibiotics?

the 20th century

What are some targets of chemotherapeutic agents

inhibition of cell wall synthesis, nucleic acid (DNA and RNA) structure and function, protein synthesis, folic acid synthesis, and interference with cell membrane structure or function

Broad spectrum drugs are effective against ____________.

more than one group of bacteria

What is a(n) example(s) of broad spectrum drugs?

tetracycline

Narrow spectrum drugs are effective against

only a specific group

What is a(n) example(s) of narrow spectrum drugs?

polymyxin and penicillins

Cephalosporins have a _________ ring that can be chemically altered

beta lactum

_________ are composed of one or more amino sugars and an aminocyclitol ring

aminoglycoside drugs

______ are protein synthesis inhibitors

tetracyclines

_________ block 30s ribosomal subunit and are effective against bacteria that have become resistant to tetracyclines

glycylcyclines

________ are the first modern antimicrobial drugs

sulfur drugs (sulfonamides)

Fluoroquinolones inhibit

DNA and RNA

Fluoroquinolones can cause serious side effects such as

seizures and other brain disturbances

______ are toxic to the kidney

polymyxins

here are fewer antifungal, antiprotozoan, and antihelminthic drugs compared to antibacterial drugs because fungi, protozoa, and helminths _______.

are so similar to human cells that drug selective toxicity is difficult to achieve

A clinical microbiologist makes serial dilutions of several antimicrobials in broth, and then incubates each drug dilution series with a standard amount of a patient's isolated pathogen. What is this microbiologist setting up?

A minimum inhibitory concentration (MIC) test

Aminoglycosides ______.

attach to the 30S ribosomal subunit and disrupt protein synthesis

Ampicillin, amoxicillin, mezlocillin, and penicillin G all have ______.

a beta-lactam ring

Antibiotics that disrupt bacterial ribosomes can also affect _______.

eukaryotic mitochondrial ribosomes

Antimicrobials effective against a wide variety of microbial types are termed ______.

broad-spectrum drugs

Beta-lactams are selectively toxic because _______.

\
they inhibit the formation of peptidoglycan, which humans do not make

Drug susceptibility testing determines _______.

the pathogen's response to various antimicrobials

Drugs that insert on the ______ ribosomal subunit prevent peptide bond formation or inhibit translocation of the subunit during translation.

50S

Each of the following target bacterial ribosomes, except ______.

\
polymyxins

Important characteristics of antimicrobial drugs include _______.

low toxicity for human tissues, high toxicity against microbial cells, a lack of serious side effects in humans, and stability and solubility in body tissues and fluids

If pathogen A is more resistant to an erythromycin disc on a Kirby-Bauer plate compared to pathogen B, then pathogen A will have a/an _____ zone of inhibition compared to pathogen B.

smaller

Selective toxicity exhibited by a drug means that _______.

the drug is effective against the target organism, but not the human host

Substances that are naturally produced by certain microorganisms that can inhibit or destroy bacteria are called ______.

antibiotics

Sulfa drugs work on _______.

folic acid biosynthesis

The cellular basis for bacterial resistance to antimicrobials include _______.

bacterial chromosomal mutations, synthesis of enzymes that alter drug structure, prevention of drug entry into the cell, and alteration of drug receptors on cell targets

The most selectively toxic drugs are those that _______.

target microbial sites that are not present in humans, e.g., the bacterial cell wall

The multidrug resistant pumps in many bacterial cell membranes function by _______.

removing the drug from the cell when it enters

The production of antibiotics by microbes evolved so that _______.

the growth of other organisms sharing their habitat was inhibited, thus giving them a selective advantage

Which antimicrobial does not interfere with protein synthesis?

1\. Aminoglycosides

2\. Tetracyclines

3\. Erythromycin

4\. Trimethroprim

5\. Chloramphenicol

Trimethroprim

Which two antibiotics affect nucleic acids of bacteria?

1\. Tetracycline and amphotericin B

2\. Trimethoprim and sulfonamides

3\. Rifampin and quinolones

4\. Tetracycline and bacitracin

5\. Penicillin and vancomycin

Rifampin and quinolones

What are some benefits of normal biota

they influence the development of organs and prevent growth of harmful microorganisms

the general antagonistic effect of good microbes have against intruder microorganisms

microbial antagonism

a condition in which pathogenic microorganisms penetrate hosts defenses, enter tissues, and multiply

infection

Factors that can cause disease

infections, genetics, aging, and malfunctions of systems or organs

the disruption of tissues or organs caused by microbes or their products

infectious disease

_______ infections caused by biota already in the body; can occur when normal biota is introduced to a site that was previously sterile.

endogenous