BIO 220 Review for exam 2
Which of the following heavy metals are still used in germicidal preparations?
Mercury Silver
Select which of the following are drawbacks to the use of metals in antimicrobial control methods.
Microbes develop resistance to these metals. They can be very toxic to human cells as well as microbial cells.
Which two of the following statements regarding heterotrophs are true?
Monosaccharides are generally good carbon sources for heterotrophs. Large organic molecules (like starch, a polymer of glucose) must be digested before absorption
A tube of clear nutrient solution ______ as microbes grow in it.
becomes turbid
Bacteria reproduce by
binary fission
A term referring to a condition free of pathogenic microorganisms, or a procedure or process designed to prevent entry of infectious agents, is
asepsis
An organism that uses inorganic CO2 as its carbon source is a(n)
autotroph
Microbes that use photosynthesis to derive organic compounds from CO2 are classified as _____, while microbes that gain their carbon in an organic form are classified as _____
autotrophs/heterotrophs
An agent that will inhibit the growth of bacteria is described as _____ whereas _____ agent will kill bacteria.
bacteristatic ;bactericidal
Sanitization, also called ______is the mechanical removal of most microbes from an animate or inanimate surface.
decontamination
Alcohol is used in which of the following applications?
degermination of skin
Chlorine compounds typically kill microbes by:
denaturing enzymes
Iodine compounds typically kill microbes by:
denaturing proteins
Chlorhexidine typically kills microbes by:
denaturing proteins. disrupting the cell wall. disrupting the cell membrane.
A virucide _____ viruses
destroys
The movement of atoms or molecules from an area of high concentration to an area of lower concentration is called
diffusion
because they can be toxic or harmful to human and other animal tissues, are normally only used on inanimate objects.
disinfectants
Boiling water can be an effective means of _____ in the clinic and home.
disinfection sanitization
Phenolics typically kill microbes by:
disrupting the cell membrane. disrupting the cell wall. denaturing metabolic enzymes.
A combination of iodine and an organic carrier (such as alcohol) that serves as a moderate-level disinfectant and antiseptic is a(n)
iodophor
Radiation that consists of short-wave electromagnetic rays (such as X rays), that cause ejection of electrons from target molecules and the creation of ions, is
ionizing radiation
Sterilization of the skin:
is highly dangerous and impractical
In commensalism, one partner benefits and the other partner
is neither helped nor harmed
Cellular growth
is stimulated by nutrients and environmental factors
The solute concentration in the environment is equal to the solute concentration within the cell under _____ conditions
isotonic
Which type of condition occurs when there are equal solute concentrations inside and outside of the cell?
isotonic
All bacteria can be divided by their energy sources as ______ or ______.
phototrophs; chemotrophs
Heat, radiation, and ultrasonic waves are physical _____ methods for controlling microorganisms.
physical
Some microbes produce ______ to protect themselves against damaging electromagnetic radiation.
pigments
During conjugation, the two bacterial cells are connected by the conjugative
pili
Bacterial cells placed in a solution where the concentration of solute within the cytoplasm is less than that of the extracellular solution would undergo
plasmolysis
If it encounters an environment that has far more solutes outside the cell compared to inside the cell, a bacterium will lose water by osmosis. This process is also called
plasmolysis
Which of the following is a type of mutation that affects only a single base pair in DNA?
point
Although they do have some drawbacks, heavy metals are used for:
preservatives. antiseptics. topical germicides.
RNA polymerase binds to the DNA region to initiate transcription.
promoter
Ultraviolet radiation induces ______, abnormal linkages between _____
pyrimidine dimers; adjacent bases on the same DNA strand
Aqueous solutions of ethyl or isopropyl alcohol are commonly used as antiseptics and disinfectants because they
quickly kill vegetative bacteria and fungi are relatively non-toxic are relatively inexpensive
Energy emitted from atomic activities and dispersed at high velocity through matter or space is called
radiation
The transfer of genes from donor to recipient in microorganisms, where the recipient strain shows a change in genetic makeup at the end, is referred to as
recombination
The main effect of cold treatment is to _____ the activity of microbes.
reduce
An obligate aerobe:
requires oxygen for survival
Prions are _____
resistant to heat and chemicals
Which cellular structure is involved in translation?
ribosome
The synthesis of proteins, or translation, occurs in structures known as
ribosomes
Which of the following describes the main function of the cell membrane?
selective barrier
Growth of microorganisms in the blood or other tissues is called
sepsis
True or false: Drinking water and utensils are reliably sanitized or disinfected by boiling water. True false question.
true
True or false: Halogens are microbicidal and can be sporicidal with longer exposure times.
true
True or false: Hypochlorites are probably the most extensively used of all chlorine compounds; however, chloramines are effective alternatives in treating water supplies.
true
True or false: Quats are rated for only low-level disinfection in the clinical setting.
true
True or false: The halogens are a group of nonmetallic elements with antimicrobial applications, including bromine, iodine, chlorine and fluorine. True false question.
true
True or false: The primary targets of microbial control are microorganisms that cause infection or spoilage.
true
True or false: Ultraviolet radiation is most lethal to microbes in wavelengths from 240 nm to 280 nm.
true
True or false: Weak tinctures of heavy metals may be used as antiseptics on intact skin.
true
The term that describes the appearance of a cloudy broth culture is _____
turbid
The term that describes the appearance of a cloudy broth culture is
turbidity
The four general cellular targets of antimicrobial agents are the cell _____, the cell _____, nucleic acid synthesis, and proteins.
wall; membrane
As the most extensively used chlorine compounds, hypochlorites are used for
wound treatment and skin cleansing food equipment sanitation swimming pool treatments
The uptake of free DNA by competent bacterial cells occurs during bacterial
Transformation
Which gene transfer method involves the uptake of free DNA by competent bacterial cells?
Transformation
A sequence of three consecutive nucleotide bases in DNA that encodes an amino acid is a(n) _____?
Triplet
Which term describes a sequence of three nucleotides that code for an amino acid in DNA?
Triplet
True or false: A bacterial cell described as competent can accept soluble DNA from the surrounding environment. True false question.
True
True or false: An agent's effect on cells is known as its mode of action.
True
True or false: DNA replication must occur prior to cell division to ensure that each new cell has a complete set of DNA chromosome(s).
True
True or false: Halogens and alcohols are examples of chemical agents used to control microbes.
True
True or false: The expression of the genotype creates traits referred to as the phenotype.
True
Prions are very resistant to chemicals and inactivation by _____, including autoclaving.
heat
An organism that must obtain its carbon in an organic form is called a(n)
heterotroph
Which organism relies upon organic compounds for its carbon and energy needs?
heterotroph
Which element plays a key role in maintaining the pH of cells?
hydrogen
Iodine compounds disrupt the native state of proteins by interfering with
hydrogen and disulfide bonding
The use of sugar or salt to preserve food creates a(n) _____ environment for the bacteria in the foods.
hypertonic
If the solute concentration of the surrounding solution is lower than that of the cell's internal environment, the solution is described as
hypotonic
An anaerobe grows best:
in the absence of oxygen
Flaming the loop in a microbiology laboratory is an example of using _____ for microbial control.
incineration
Which of the following should be considered when initially choosing a method of microbial control?
- Is it cost and labor-efficient - Is sterilization needed - Can it withstand physical or chemical treatments - Is the item reusable or disposable - Is it safe - Will it penetrate effectively
Antimicrobial solutions with water as the solvent are called _____, whereas antimicrobial solutions with alcohol or water-alcohol mixtures as the solvent are called _____
Aqueous; tinctures
The root that is used to indicate the killing of microorganisms is
-cide
How many replication forks are formed from opening a section of a circular DNA molecule during replication?
2
The percentage of oxygen in Earth's atmosphere is about
20%
If a DNA molecule contains 15% adenine nucleotides, what percent of cytosine does it contain?
35%
Moist heat is: Dry heat is:
60*C to 135*C 160*C to Several thousand *C
Most bacterial plasmids carry an origin of replication and at most ______ genes.
A few hundred
Which two of the following statements regarding eukaryotic transcription and RNA processing are correct?
A series of adenosines is added to the mRNA. Splicing to remove introns occurs in the nucleus.
Which describes a plasmid?
A small circular piece of DNA that replicates its nonessential genes independently of the chromosome.
Which of the following are examples of chemical agents used to control microbes?
Alcohols Aldehydes Oxidizers Heavy metals Phenolic compounds
If a cell is in a solution that is hypotonic relative to the cytoplasm, how will water move?
into the cell by osmosis
Which test is a method of detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria?
Ames
Detection of mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria is called the _____ test.
Ames test
During translation elongation, peptide bonds form between
Amino Acids
Which is the main event of translation elongation?
Amino acids are joined by peptide bonds
Triclosan is a(n) Blank______ that has been banned for consumer use.
phenolic
The genes of which microorganism(s) are arranged as operons?
Bacteria
Phase variation is when bacteria turn on or off a set off genes, which leads to obvious changes in their
phenotype
Which is true regarding adenine and guanine?
Both are Purines
Which of the following are desirable qualities in a germicide?
Broad-spectrum microbial action Solubility in a solvent Penetrating ability Rapid action
Which of the following acronyms is used to describe the collection of elements which compose 96% the dry weight of a cell?
CHNOPS
True or false: The parent strands in a DNA molecule are used as templates to synthesize complementary strands of DNA.
True
A discrete cellular structure composed of a neatly packaged DNA molecule is
Chromosome
A critical concern for the food packaging industry is the elimination of endospores of
Clostridium botulinum
Horizontal gene exchange via a cellular bridge in bacteria is called
Conjugation
During conjugation, the donor cell generally retains a copy of the genetic material being transferred. This is termed a ______ process.
Conservative
According to the rules of complementary base pairing, the nitrogenous base _____ forms hydrogen bonds with guanine. (Spell out the full name of the base.)
Cytosine
Nonionizing radiation causes the formation of abnormal bonds within _____ leading to mutations
DNA
Which enzyme adds nucleotides to a growing DNA strand?
DNA Polymerase
What is the central dogma hypothesis of genetics?
DNA encodes RNA which encodes protein
Which is the main enzyme in elongation of a DNA strand during replication?
DNA polymerase
The enzymes that function in DNA replication.
DNA polymerase Helicase Ligase
How is phenol used in microbial control?
Disinfection of drains Treatment of cesspools Disinfection of animal quarters
Incineration is a good method of microbial control in which two instances?
Disposal of medical waste Flaming the loop in a microbiology laboratory
Ensuring that the DNA code will be maintained during cell growth and cell _____ is one of the two essential effects of the structure of DNA.
Division
Select the statement that most accurately reflects the use of heat as an antimicrobial agent.
Dry heat methods exert their effect by dehydrating cells.
Which is true regarding DNA replication?
Each new DNA helix contains one parent strand and one newly synthesized strand.
Which items can be sanitized by boiling water prior to safe, acceptable use?
Eating utensils Drinking water Bedding and clothing
Which three key features of the active transport process are shown in this diagram?
Energy in the form of ATP is required. A specific membrane protein is used as a transporter. Nutrients are transported against their concentration gradient, from low to high concentration.
True or False: Eukaryotic chromosomes are composed of DNA and RNA
False
True or False: Within a nucleotide, the phosphate group is linked to the 3' carbon of the pentose sugar
False
True or false: A cell with an integrated F factor transmits its genes at lower frequency than does a cell with a free plasmid in the cytoplasm.
False
True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells
False
True or false: Plasmids are insertion sequences that can lead to changes in genotype within a cell or between cells.
False
True or false: Routine skin antisepsis often is completed using phenolics.
False
True or false: Operons are found in fungi and helminths.
False; only bacteria and archaea
What is the main effect of nonionizing radiation on cellular targets?
Formation of abnormal DNA linkages
A segment of DNA that contains the necessary code to make a protein or RNA is called
Gene
A sequence of DNA nucleotides that codes for one functional protein or RNA is called a
Gene
The complete set of chromosomes and genes in an organism is referred to as the
Genome
Which term represents all of the genetic information within a cell?
Genome
The shortest length of time required to kill all test microbes at a specified temperature is referred to as the thermal
death time
Which is a purine?
Guanine
Aerobes have which two of the following characteristics?
Have enzymes that can detoxify harmful oxygen products Can use gaseous oxygen in their metabolism
In DNA replication, _____ unwinds (unzips) the double helix, primase synthesizes the short RNA primer, and DNA _____ adds nucleotides to the new chain.
Helicase/Topoisomerase; polymerase
In bacterial conjugation, which type of donor has the fertility factor integrated into the chromosome?
Hfr
When organisms acquire genes which did not come directly from parent organisms it is referred to as _____ gene transfer
Horizontal
Select which of the following are examples of dry heat methods of control.
Hot air Incineration
About 96% of the dry cell weight is composed of which elements?
Hydrogen Nitrogen Carbon Sulfur Phosphorous Oxygen
Which two of the following are transport functions of the cell membrane?
Import nutrients Export waste materials
How does RNA differ from DNA in bacteria and eukaryotes?
In RNA, uracil replaces thymine RNA is single-stranded
What are the effects of adding pressure to water in an autoclave?
Increases temperature of steam Increases boiling point of water
The lac operon in E. coli regulates the metabolism of
Lactose
Which is FALSE regarding binary fission?
Like meiosis in eukaryotes, it specifically produces daughter cells with genetic variation.
Which two of the following statements regarding plasmids are true?
Many bacteria carry plasmids in addition to their chromosome. Plasmids may contain genes that specify resistance to antibiotics.
Choose the condition under which glutaraldehyde is a good choice for sterilizing materials.
Materials that can be damaged by heat
A nitrogen-containing structure found in DNA and RNA that provides the basis for the genetic code is a
Nitrogenous Base
Building blocks of DNA, called _____, contain the same sugar and phosphate, but different nitrogenous bases.
Nucleotides
Delicate medical instruments such as endoscopes become highly contaminated with human tissues and fluids, and should be sterilized in a low-temperature cabinet using which sterilants?
Peracetic acid Hydrogen peroxide
True or false: The structure of DNA is essential for providing variety since the order of nucleotides is responsible for the unique qualities of each organism.
True
When a cell is actively growing, the arg operon is ______, and arginine is ______.
On; actively synthesized
The control locus of the lac operon contains a region of DNA that acts as an on/off switch for transcription called a(n) Blank
Operator
The heat treatment of perishable liquids to destroy heat-sensitive vegetative cells and prevent infection and spoilage is called
Pasteurization
Areas of the genome containing multiple genes which contribute to a new trait for the organism that increases its ability to cause disease are termed
Pathogenicity Islands
Which of the following are areas of the genome where multiple genes exist that are coordinated to create a new trait, making the bacterium more pathogenic?
Pathogenicity islands
True or false: The two primary iodine preparations are free iodine and iodophors.
True
The process of bacteria turning on or off a group of genes that changes their phenotype in a heritable manner is called
Phase Variation
The process of bacteria turning on or off a group of genes that changes their phenotype in a heritable manner is called _____
Phase Variation
The characteristics resulting from the interaction of the particular genetic makeup of an organism and the environment is the _____ of that organism
Phenotype
Within a nucleotide, the ____ group is linked to the 5' carbon of the pentose sugar
Phosphate
A small circular segment of DNA found in the cytoplasm of bacteria that is capable of independent replication and usually contains nonessential genes is called a(n)
Plasmid
During replication,_____ synthesizes primer sequences.
Primase
Which enzyme synthesizes primer sequences during replication initiation?
Primase
The element hydrogen is important for which of the following functions?
Producing weak and easily reversible bonds between molecules Maintaining pH Providing free energy in oxidation-reduction reactions of cell respiration
RNA polymerase binds to the DNA _____ region to initiate transcription.
Promoter
RNA polymerase binds to which region of DNA to begin transcription?
Promoter
The control locus of the lac operon is composed of the ______, a region of DNA that is recognized by RNA polymerase.
Promoter
Choose the four general cellular targets of antimicrobial agents.
Protein function Nucleic acid synthesis The cell wall The cell membrane
The union of two adjacent pyrimidines on the same DNA strand, brought about by exposure to ultraviolet light, is called
Pyrimidine Dimer
Plasmids that encode resistance to a variety of antimicrobial agents and heavy metals are called ______ plasmids or factors.
R
Genes encoding resistance to antimicrobial drugs can spread to different strains, species, and even genera, most commonly through conjugative transfer of
R Plasmids
The antibiotic rifamycin, used to treat tuberculosis, binds and inhibits the activity of
RNA ploymerase
The enzyme that transcribes DNA into RNA is
RNA polymerase
Which enzyme transcribes DNA into RNA?
RNA polymerase
Complete the following sentence with the correct series of transcriptional terms: ______ binds the ______ to begin ______.
RNA polymerase; DNA promoter region; transcription
During transcription, RNA polymerase synthesizes ______ from a(n) ______ template.
RNA; DNA
Which term refers to the transfer of genes from donor to recipient microorganisms?
Recombination
During DNA ____ the DNA is duplicated prior to binary fission.
Replication
The Y-shaped point on a replicating DNA molecule where the DNA polymerase is synthesizing new strands of DNA is the _____ fork.
Replication
Which are goals of pasteurization?
Retention of liquid qualities Reduction of microbial load
During DNA replication the newly made double helices are composed of one parent template and one newly synthesized strand and therefore the replication is considered _____?
Semiconservative
Which two of the following are examples of degermation?
Surgical handscrub Wound cleansing
Which of the following are effects of ionizing radiation on food products?
Small decreases in thiamine Changes in texture of some foods Killing of bacterial pathogens
Which two of the following statements are accurate regarding heterotrophs?
Some heterotrophs are restricted to just a few carbon substrates. Amino acids may be a good carbon source for a heterotroph.
A particular part of the host genome is included in the virus during ______ transduction.
Specialized
Mutations that occur because of errors in DNA replication are termed
Spontaneous
An agent that can destroy bacterial endospores is a
Sterilant
Which three of the following are common uses for glutaraldehyde?
Sterilize respiratory therapy equipment Sterilize kidney dialysis machines Sterilize dental equipment
What factors must be considered in order to adequately sterilize using heat?
Temperature Length of exposure
In a DNA molecule the parent strands are used as a(n) _____ to synthesize a complementary strand of DNA.
Template
What did Griffith's experiment using Streptococcus pneumoniae demonstrate?
That DNA released from a dead cell can be transferred to a live cell.
Which two statements regarding eukaryotic transcription and RNA processing are correct?
The exon-intron junction is recognized by a spliceosome. Transcription occurs before splicing.
How do an Hfr cell and an F+ cell differ?
The plasmid is integrated into the chromosome of an Hfr cell but not in an F+ cell.
Vertical Gene Transfer
Transfer of DNA from parent organisms during reproduction
The different types of nucleotides in DNA contain
The same sugar and phosphate, but different nitrogenous bases
Which is true of a hypotonic condition?
There is a higher solute concentration inside the cell than outside the cell.
You release a small drop of methylene blue dye into a beaker of water. What happens to the molecules of blue dye?
They move from the region of high concentration to regions of low concentration.
The process of copying DNA into messenger RNA is
Transcription
Which recombination method involves transfer of DNA via bacteriophages?
Transduction
Horizontal gene transfer
Transfer of DNA from a source other than the parent organisms
A type of nonionizing radiation that is routinely used to disinfect air and the surfaces of solid objects is
Ultraviolet (UV)
Unlike DNA, RNA contains the nitrogenous base
Uracil
Facultative anaerobes have which three of the following characteristics?
Utilizes aerobic respiration when oxygen is present Can grow in the absence of oxygen Do not require oxygen for their metabolism
Iodine compounds are commonly used for:
antisepsis of skin. treatment of skin wounds. disinfection of medical equipment.
is the destruction of most microbes using chemicals on a living surface such as the skin.
antiseptic
Aqueous solutions of ethyl or isopropyl alcohol are commonly used as antiseptics and disinfectants because they _____
are relatively inexpensive are relatively non-toxic quickly kill vegetative bacteria and fungi
In parasitism, one partner is helped and the other is
harmed
Most microorganisms live and grow in habitats between pH 6 and pH 8 because enzymes and other cellular substances are damaged by solutions with pH values below 7, called strong,_____ and solutions with more extreme pH values above 7, called strong _____.
acids; bases
The arginine operon is "on" when the cell is
actively growing
A microorganism that can use gaseous oxygen in its metabolism and possesses enzymes needed to process toxic oxygen products is a(n) _____ organism
aerobe
A sterile object is free of _____
all viable microorganisms and viruses
Cellular growth is characterized by:
an increase in cellular components. an increase in cell number. an increase in cell size.
A particular microorganism produces a substance that kills another microorganism in its environment. This is an example of
antagonism
An agent that kills fungal spores, hyphae and yeasts is called a
anti fungal
If an agent disrupts the cell wall, the cell is likely to experience:
death by lysis
Sodium hypochlorite is also known as
bleach
One approach to controlling bacteria and fungi is by _____ the synthesis of the cell wall.
blocking
Moist heat occurs in the forms of
boiling water steam
A germicide with a(n)_____ spectrum is most desirable.
broad
A microbe's nutritional type (e.g., chemoheterotroph) is determined by its sources of
carbon and energy
The genes of the lac operon in E. coli encode enzymes that
catabolize lactose
The enzyme that converts hydrogen peroxide, derived from a harmful by-product of oxygen, to water and oxygen is
catalase
The primary targets of microbial control are microorganisms that
cause infection cause food spoilage
The bacterial cell structure specialized for transport is the
cell membrane
Antiseptics are ______ agents applied to the skin to inhibit vegetative bacterial cells.
chemical
Which term describes organisms which acquire their energy from chemical compounds?
chemotrophs
Gaseous and liquid _____ compounds are mostly used for large-scale water disinfection.
chlorine
A type of symbiotic relationship between two organisms in which one species derives benefit without harming the other is called
commensalism
Bacterial cells that can accept soluble DNA from the surrounding environment are referred to as
competent
Donor and recipient bacterial cells are connected by the pilus during
conjugation
In which of the following genetic recombination processes in bacteria is DNA transported between bacterial cells when a cellular bridge is formed?
conjugation
The three methods of gene transfer in bacteria are
conjugation transformation transduction
DNA repair enzymes have _____ as their substrate
damaged DNA
The permanent termination of a particular organism's vital processes is called _____. Special qualifications are often needed to define and delineate this phenomenon in microbes.
death
Alcohols are effective against:
enveloped viruses. fungal cells. resistant bacteria.
Chlorine compounds usually kill microbes by denaturing _____ and thereby disrupting metabolic reaction
enzymes
DNA damage can be resolved by
enzymes
A spontaneous mutation arises in DNA from
errors in DNA replication
The gas that is most effective for killing endospores is _____
ethylene oxide
the gas ______ Is used to sterilize prepackaged medical devices, syringes, and Petri dishes.
ethylene oxide
A microbe that does not require oxygen for its metabolism, and is capable of growth in the absence of it, is called a(n)
facultative anaerobe
True or false: A process that completely removes or destroys all viable microorganisms, including viruses, from an object or habitat is referred to as disinfection.
false
True or false: Halogens are only microbistatic.
false
True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.
false
True or false: Iodine compounds are commonly used for household cleaning.
false
True or false: Ionizing radiation is not an effective method of controlling microbes in food products.
false
True or false: Mutations are always harmful to cells.
false
True or false: Nonphotosynthetic microbes are neither helped nor harmed by exposure to visible light.
false
True or false: Only a few microorganisms are killed by iodine even if proper concentrations and exposure times are used.
false
True or false: Phenolics typically kill microbes by inhibiting protein synthesis.
false
True or false: Sepsis is a term referring to a condition free of pathogenic microorganisms or a procedure or process designed to prevent entry of infectious agents.
false
True or false: Sterilization methods are often used to prepare the human body for surgical procedures.
false
True or false: There are several degrees of sterility, based on the destruction of endospores.
false
In filtration, a fluid is strained through a filter with openings large enough for the ______ to pass through but too small for ______ to pass through.
fluid; microorganisms
The two primary iodine preparations are
free; iodophors
Random fragments of host DNA are taken up by the bacteriophage during assembly in Blank______ transduction.
generalized
In binary fission, the doubling time of a particular microbial species is also known as its
generation time
Which term describes the length of time of a microbial species needs to divide?
generation time
The dosage of radiation is measured in
grays
A graphical representation of the change in population size over time is a(n)
growth curve
A group of nonmetallic elements with antimicrobial applications, including bromine, iodine, chlorine, and fluorine, are called _____
halogens
Chlorhexidine solutions are commonly used for:
hand scrubs. mucus membrane irrigation. prepping skin for surgery.
Which two types of macromolecules make up the majority of the cell membrane in microorganisms?
lipids and proteins
The two types of macromolecules that make up the majority of the cell membrane in microorganisms are _____ and _____
lipids; proteins
Quaternary ammonium compounds are considered to be _____ -level disinfectants.
low
In active transport, molecules are moving across the membrane from an area of ______ concentration to an area of ______ concentration.
low; high
If an agent disrupts the cell wall, the cell becomes fragile and is destroyed by
lysis
Which of the following is NOT a way that a chemical control agent damages a cell wall?
making it more permeable
The component responsible for preventing the loss of important molecules, and stopping the entry of damaging substances, is the cell
membrane
An aerobic bacterium that requires oxygen at a concentration less than that in the atmosphere is a(n
microaerophile
Lower temperatures are usually Blank______; higher temperatures are usually Blank______
microbistatic; microbicidal
The lowest temperature that permits a microbe's continued growth and metabolism is called the _____ temperature.
minimum
An agent's adverse effect on cells is known as its
mode of action
In terms of using heat as an agent of microbial control _____, heat methods operate at lower temperatures and shorter exposure time versus _____ heat methods.
moist; dry
A permanent inheritable alteration in the DNA sequence of a cell is a(n)
mutation
A small number of _____ are considered beneficial in that they provide the cell with a useful change in structure or physiology. Antibiotic resistance in bacteria is an example.
mutations
Which of the following is the most common gas on Earth?
nitrogen
Antagonism is a ______ association occurring when members of a community _____
nonsymbiotic; compete with each other
The process by which nutrients are acquired from the environment, and used in cellular activities such as metabolism and growth, is called
nutrition
_____ is the acquisition of chemical substances by organisms for use as an energy source or as building blocks of cellular structures.
nutrition
An organism that requires oxygen for survival is called a(n) _____ or strictly aerobic organism.
obligate
sterilization is:
only necessary for certain groups of microbes. generally reserved for inanimate objects.
disinfection destroys
only vegetative bacterial cells
A microorganism that lives in a habitat with a high solute concentration is a(n)
osmophile
Which term is used exclusively to describe water's movement across a selectively permeable membrane?
osmosis
Which is the pH range for habitats in which most microorganisms can survive and grow?
pH 6 to pH 8
A relationship between two organisms where the host is harmed and the colonizer benefits is called
parasitism
A quantitative comparison of the effectiveness of a chemical disinfectant to that of phenol is the ______ ______.
phenol coefficient
Plasmolysis of bacteria in foods occurs when high concentrations of salt or sugar are added to the foods creating a(n) ____ environment
smooth; pores
An osmophile lives in a habitat with a high ______ concentration.
solute
What type of agent specifically destroys bacterial endospores?
sporicide
A process that completely destroys or removes all viable microorganisms, including viruses, from an object or habitat, is referred to as
sterilization
The destruction of all microbial life is called _____, whereas _____destroys most microbial life, thus reducing contamination on inanimate surfaces.
sterilization; disenfection
Because of concerns about botulism, commercial food canneries must ______ food items.
sterilize
An agent that disrupts the lipid bilayer of membranes, and alters the membrane's permeability, is a(n)
surfactant
Cells in a pure water environment will
take in water, swell, and burst
Conjugation is a conservative process, meaning that
the donor retains a copy of the genetic material being transferred
The antibiotic rifamycin can be used to treat tuberculosis because
the drug is more active against bacterial RNA polymerase than the human enzyme
Disinfectants are normally only used on inanimate objects because:
the high concentrations needed are harmful to living tissues.
The number of bacterial cells is plotted as a function of _____ to show the _____ of the population.
time; growth
RNA polymerase binds the DNA promoter to initiate
transcription
The method of DNA recombination in bacteria that involves the transfer of DNA via bacteriophages is called
transduction
Griffith's experiment using Streptococcus pneumoniae demonstrated the process of
transformation
Insertion sequences that can lead to changes in genotype within a cell or between cells are called "jumping genes" or
transposons
True or false: A mutation is an alteration in the DNA sequence or content of a cell that is passed on when the cell divides.
true
True or false: A surfactant is an agent that disrupts the lipid bilayer of a membrane, creating leaky spots that alter the membrane's permeability.
true
True or false: Chlorhexidine typically kills microbes by disrupting the cell membrane or denaturing proteins.
true
True or false: Death involves the permanent termination of a particular organism's vital processes.
true
