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Microbiology Set 2
Exam 2 Ch. 5-8
| Question | Answer |
|---|---|
| A __________ is performed to check whether or not a bacterium can produce an enzyme or not | biochemical test |
| __________ test is performed to see whether or not a microbe can ferment of use a particular or carbohydrate for energy. | Fermentation |
| Use light as primary energy source | Phototrophs |
| Depends on redox reactions of organic and inorganic compounds for energy | Chemotrophs |
| (Self-feeders)- Use CO2 (inorganic carbon source); AKA lithotrophs (rock eating) | Autotrophs |
| (Feeds on others)- Require an organic carbon source, AKA organotophs | Heterotrophs |
| The requirements of microbial growth are both physical and chemical. What are 3 examples physical growth requirements? | -Temperature -pH -Osmotic Pressure |
| Microorganisms that grow best in cold temperatures are called | psychrotrophs |
| Prefer a moderate temperature | mesophiles |
| are microorganisms that prefer hot temperatures | thermophiles |
| Which of the above groups of microorganisms are responsible for most human disease and common spoilage? | Mesophiles |
| Molds and yeasts are examples of ______________ because they prefer to grow in an acidic pH of ____. | -acidophiles -5-6 |
| Why is nitrogen required for microbial growth? How can some organisms obtain nitrogen? | Most bacteria decompose proteins and reuse the N in the aa's to synthesize new protein; some bacteria use NH4+ or NO3- |
| Sulfur is used to synthesize sulfur containing amino acids and vitamins like _______ & ________, and is acquired through the decomposition of proteins, or sources such as sulfate of hydrogen sulfide. | -Thiamine -Biotin |
| Phosphorus is required for microbial growth because it is found in _______, _____,_____,&________? | -DNA -RNA -ATP -Cell Membranes |
| One requirement for microbial growth may be the absence of presence of oxygen. Microbes that require oxygen are called________? | Aerobes |
| ____________ are microbes that use O2 when present, but can continue growth by fermentation of anaerobic respiration if O2 is not available (so doesn't require it) | Facultative Anaerobes |
| ____________ are microbes that are totally unable to use O2 for growth because it is toxic to them. Name an example of this type of organism. | -Obligate anaerobes -Clostridium |
| ___________ cannot use O2 for growth, but tolerate if fairly well and are not killed in its presence. | Aerotolerant |
| ___________ are microbes that are aerobic and require oxygen, but grow only in O2 concentrations lower than those in air. | Microaerophiles |
| For many microorganisms,oxygen is toxic. Aerobes, facultative anaerobes, facultative anaerobes, & aerotolerant anaerobes can survive in the presence of O2 because they have certain enzymes that neutralize these toxic forms of O2. What are these 3 enzymes? | -Singlet Oxygen -Peroxide anion -Superoxide free radicals |
| Why are biofilms an important factor in human health and what can be used to inhibit the formation of biofilms? | They are resistant to microbicides, dessication, antibiotics, and body's immune system; 1) Incorporate antimicrobials into surfaces on which biofilms might form. 2) Lactoferrin |
| What is agar? | Complex polysaccharide extracted from red algae |
| A __________ defined medium is one in which the exact chemical composition is known (so you know exactly how much of each nutrient is present) and often used to grow fastidious organisms (ones that require many growth factors) | Chemically |
| A _______ medium is one in which the exact chemical composition varies slightly from batch to batch and is used to grow most heterotrophic bacteria and yeasts (example include Nutrient agar or Tryptic soy agar) | Complex |
| _____ media chemically removes molecular O2 that might interfere with the growth of anaerobes by using chemicals and heat to drive off any absorbed O2. | Reducing |
| Some bacteria, called capnophiles, require an increased CO2 concentration for growth. Name 2 methods that can be used to aid in their growth. | -Candle Jar -CO2 Packet |
| What is the purpose of selective media? | Suppresses the growth of unwanted microbes & encourages the growth of desired ones |
| What is the purpose of differential media? | Makes it easier to distinguish colonies of the destined organism |
| An _______ media is used to encourage the growth of a particular microorganism so that we can increase the microbes number to detectible levels. | Enrichment Media |
| How do we obtain pure cultures? | Spreading bacteria on the surface of a solid medium so that a single cell occupies an isolated portion of the agar surface. |
| Microbes can be preserved for long periods of time by _________ or _________. | -deep-freezing -50 to -95 degrees C. -Lyophilization( freeze-drying -54--72 degrees C) |
| The normal reproductive method of bacteria is binary fission, in which a single cell divides into 2 identical cells. What are some other ways bacteria may reproduce? | 1) Budding-form a bub that enlarges until it is the size of the parent cell and then separates 2) Conidiospores- (actinomycetes) 3) Fragmentation of filaments |
| The time required for a bacterial cell to divide or the population to double in known as _________. | Generation time |
| Little or no change in cell numbers; metabolic activity is high | Lag Phase |
| Bacteria multiply at the fastest rate possible under given conditions | Log Phase |
| There is an equilibrium between cell division and cell death | Stationary Phase |
| The number of deaths exceeds the number of new cells formed | Death Phase |
| What are some direct methods used to measure microbial growth? | 1) Plate Count: Pour plate, spread plate 2) Filtration 3)Most Probable Number (MPN) 4)Direct Microscopic count |
| What are some indirect methods to measure microbial growth? | 1) Turbidity 2) Metabolic Activity 3) Dry Weight |
| Removal of all microbial life (including prions) | Sterilization |
| Removal of pathogens from inert surface | Disinfection |
| Removal of pathogen from living tissue | Antisepsis |
| Removal of microbes from a limited area | Degerming |
| Lower microbial counts on eating utensils | Sanitization |
| Kills microbes | Biocide |
| Inhibiting, not killing, microbes | Bacteriostasis |
| Bacterial population die at a constant logarithmic rate when _______ or treated with _________________. | -Heated -Anti-microbial chemicals |
| What are 4 factors that influence the effectiveness of antimicrobials? | 1) Number of microbes 2) Environmental Influences 3) Time of exposure 4) Microbial Characteristics |
| Various agents kill or inhibit microbial growth in different ways. Name and explain 2 modes of action that agents may use to control microbial growth. | 1) Alteration to membrane permeability 2) Damage to proteins & nuclear acids |
| The thermal death point (TDP) is the lowest temperature at which cells in a culture are killed in ___________ min. | 10 minutes |
| What is the TDT? | TDT- Thermal Death Time: Time to kill all cells in a culture |
| What is the DRT? | DRT- Decimal reduction time: Minutes to kill 90% of a population at a given temperature |
| How does moist heat(i.e. boiling) kill microbes? | By coagulating proteins (denaturation), which is caused by breakage of H bonds |
| An __________________, which, under 15 psi and a temp of 121 degrees Celsius, kills microbes and endospores in 15 minutes. (Does not kill prions unless temp increased and NaOH added) | Autoclave |
| ___________ is the process of applying heat for a short time in order to reduce spoilage and pathogenic organisms | Pasteurization |
| What is the term used to describe organisms that are heat-resistant but unlikely to cause disease or refrigerated milk to spoil? | Thermoduric |
| Dry heat kills by _______ effects. Name two examples of controlling microbial growth using dry heat. | -oxidation 1) Direct Flaming 2) Hot Air Sterilization |
| Name several other physical methods of controlling microbial growth/ | -Filtration -Low Temp.: Refrigeration, deep freezing, lyophilization -High Pressure -Desiccation -Osmotic Pressure -Radiation Damage DNA |
| Radiation, another physical method of controlling microbial growth, kills microorganisms by damaging DNA, and may include_________ radiation, which penetrates tissues and forms free radicals. | Ionizing |
| ________ radiation, which has a lower degree of tissue penetration and damages cells by making thymine dimers in DNA that interfere with DNA replication. | Nonionizing |
| There are 4 main principles that must be considered in order for a substance to be an effective chemical disinfect. Name these 4 principles. | 1) Concentration 2) Orgainc Matter 3) pH 3) time |
| What are 2 methods used for evaluating the effectiveness of a disinfectant? | 1) Use-dilution test 2) Disk diffusion method |
| ______________ or carbolic acid, was once a frequently used disinfectant, but now is rarely used because it irritates the skin and has a strong odor, however, it is often used in throat lozenges because of its local anesthetic effects. | Phenol |
| How do Phenolics work? | Injure plasma membranes, inactive enzymes, denature proteins |
| Name a commonly used household product that is an example of a phenolic compound. | Lysol |
| ___________ is a bisphenolic compound that is commonly used in nurseries because it is effective against staph and strep bacteria. | Hexachlorophene |
| ___________ is another bisphenolic compound that has been incorporated into cutting boards, handles of knives, soaps, face washes, and toothpastes. | Triclosan |
| _______ is an example of a halogen that is one of the oldest and most effective antiseptics. | Iodine |
| The exact killing mechanism of ____________, another halogen, is unknown, but it is believed that it works by interfering with cellular enzymes. | Hypochlorous Acid |
| ____________ effectively kill bacteria and fungi, but not endospores of nonenveloped viruses. | Alcohols |
| The mechanism of action for Alcohols involves protein denaturation, as well as disrupting ________ and dissolving _________. | -Membranes -Lipids |
| Several _______ are used as disinfectants because of their oligodynamic action by acting to denature proteins. | Heavy Metals |
| ___________ is a heavy metal that was commonly placed in the eyes of newborns to prevent blindness associated with gonorrheal infections, but has now been replaced by antibiotics. | AgNO3-(gonorrheal ophthalmia neonatorum) |
| Soaps and detergents have little antiseptic properties, but are good _______ agents. | Surface-active |
| Quaternary ammonium compounds are cationic detergents attached to an _________ ion. These compounds are most effective against gram + organisms, and less active against gram - bacteria | NH4+ |
| ___________ & ______________ and quaternary ammonium compounds that are colorless, odorless, tasteless, nontoxic and stable, but are inactivated by organic matter, soaps, detergents, and surfaces like gauze. | Zephiran & Cepacol |
| __________ is a type of chemical food preservative that preserves the red color of meat and prevents the germination and growth of botulinum endospores. | Sodium nitrate |
| _____ are among the most effective antimicrobials and include formaldehyde and glutaraldehyde | Aldehydes |
| _____________ is not a good antiseptic for open wounds because it is quickly broken down by catalase into water and oxygen, but is useful in deep anaerobic wounds and as a surface disinfectant. | Hydrogen Peroxide |
| Name the top 3 microbes or microbial characteristics that contribute to resistance to physical and chemical methods of controlling microbial growth. | 1)Prions 2) Endospores of bacteria 3) Mycobacteria |
| __________ is the study of what genes are, how they carry information, how information is expressed, and how genes are replicated | Genetics |
| A _____ is a segment of DNA that encodes a functional product, usually a protein. | Gene |
| A ___________ refers to all genetic material in a cell | Genome |
| _____________ refers to the gene of an organism | Geotype |
| ____________ refers to the expression of an organisms genes | Phenotype |
| DNA is the blueprint for a cell's ________, and is obtained from a __________ or from another cell. | -Proteins -parent cell |
| Bacterial DNA is __________ & ___________, and is associated with proteins. | -Single -Circular |
| DNA is made up of polymer of nucleotides, which are composed of: | Sugar, phosphate & nitrogenous base |
| What does thymine always base pair with? | Adenine |
| What does guanine always base pair with? | Cytosine |
| Describe the process of DNA Replication | Slide 6-Chapter 8 Powerpoint |
| DNA elongation is catalyzed by what enzyme? | DNA Polymerase |
| In what direction are new nucleotides added to the new DNA strands? | Grow in opposite directions |
| What provides the energy for the assembly of new DNA strands? | Removal of two phosphate groups |
| What enzyme connects the Okazaki fragments? | DNA ligase |
| The process of converting DNA into RNA is called ____________. | Transcription |
| Transcription begins when RNA polymerases binds to a __________ sequence, and stops when it reaches a _____________ sequence. | -Promoter -Terminator |
| ___________ is the process of converting mRNA into proteins. | Translaction |
| __________ codons code for amino acids and _______________ codon do not code for amino acids | -sense -nonsense |
| In prokaryotes, translation of mRNA begins at the start codon ____, which codes for _________________ | -AUG -formylmethionine |
| Translation ends at stop codons, which include______, _______,& ________. | -UAA -UAG -UGA |
| What does tRNA do during translation? | Each time an amino acid is added to the growing chain, a tRNA molecule forms base pairs with its complementary sequence on the mRNA molecule, ensuring that the appropriate amino acid is inserted into the protein. |
| Because transcription and translation take place in the cytoplasm in prokaryotic cells, transcription and translation can occur___________. | simultaneously |
| What are 3 differences between transcription in prokaryotes and eukaryotes? | Slide 23- Chapter 8 Powerpoint |
| ___________ enzymes are expressed at a fixed rate (so, the genes for them are constantly turned on), and include enzymes that are used in glycolysis or those involved in processes like DNA replication, while other enzymes are inducible or repressible. | Constitutive |
| What is repression? | Genetic regulation that decreases enzymes synthesis or inhibits gene expression |
| _________ or carbolic acid, was once a Frequently use disinfectant but now is really used because it irritates the skin and has a strong odor however it is often used in throat lozenges because if it’s local anesthetic effect | Phenol |
| How do phenolic work? | Injure plasma membranes, inactivate enzymes, denature proteins |
| What is a commonly used household product that is an example of a phenolic compound? | Lysol |
| ________ is a bisphenolic compound that is commonly used in nurseries because it is effective against staph and strep bacteria. | Hexachlorophene |
| ______ is another bisphenolic compound that has been incorporated into cutting boards, handle of knives,soaps,face washes, and toothpastes. | Triclosan |
| ______ is an example of a halogen that is one of the oldest and most effective antiseptics. | Iodine |
| The exact killing mechanism of _________, another halogen, in unknown, but it is believed that it works by interfering with cellular enzymes. | Hypochlorous Acid |
| __________ effectively kill bacteria and fungi, but not endospores or non enveloped viruses. | Alcohols |
| The mechanism of action of Alcohol involves protein denaturation, as well as disrupting ________ and dissolving ______. | -membranes -lipids |
| Several _______ are used as disinfectants because of their oligodynamic action by acting to denature proteins. | Heavy metals |
| ________ is a heavy metal that was commonly placed in the eyes of newborns to prevent blindness associated with gonorrheal infections, but has now been replaced by antibiotics. | AgNO3 |
| What is induction? | Process that turns on the transcription of a gene or genes |
| Protein synthesis in bacteria is controlled by _________, which are groups of coordinately regulated structural genes with related metabolic functions, plus the promoter and operator sets that control their transcription. | Operons |
| Name an example of an inducible Operon. | Example: lacoperon like in E. Coli |
| Name an example of a repressible operon. | Gene that produces the repression protein. Ex: shunting\ turning of gene of tryptophan |
| A change in genetic material that may be neutral (silent), beneficial, or harmful. | Mutation |
| Silent mutation commonly occurs when one DNA nucleotide is substituted for another, especially in which position? | 3rd position |
| A base substitution is a type of _________, which are the most common and occur when one nucleotide is replaced by another nucleotide. | Point mutation |
| In a ________mutation, a stop codon is produced, which prevents the synthesis of the protein. | Nonsense |
| In a ________ mutation, the amino acid that is coded for is changed, resulting in an altered protein. (Sickle-cell anemia) | Missense |
| In a __________ mutation,multiple nucleotide pairs are inserted or deleted,which shifts the reading frame of the gene, resulting in an inactive proteins. | Frameshift |
| Spontaneous mutations are generally caused by mistakes made during ______________, which alter DNA at random locations. | Mutagen |
| Aside from spontaneous mutations, what else causes mutations? | -chemical mutagens (ex: nitrous acid) -radiation |
| Nitrous acid is a chemical mutagen that alters _______ so that it pairs with ________. | -adenine -cytosine |
| ____________ are chemicals that are structurally similar to normal nitrogenous Bess but have slightly altered base-pairing properties and results in base-pair substitutions. | Nucleoside Analog ( many anti-virus drugs are) |
| Some chemical mutagens can cause nucleotide deletions or intersections, which can result in frameshift mutations. Name 2 chemical mutagens that may do this. | -Benzopyrene -Aflataxin |
| Frameshift mutagens are often potent __________. | Carcinogens |
| Exposure to UV light (radiation) can result in mutations in the DNA because of the formation of __________, which form harmful covalent bonds between thymine bases. | Thymine dimers |
| Type of light-repair enzyme that uses visible light energy to separate the dimer back to the original 2 thymines | Photolyase |
| Group of genes that produce enzymes that cut out distorted segments of DNA and use DNA polymerase to synthesize new DNA to repair damage. (Not restricted to UV-induced damage) | Nucleotide Excision Repair (NER) |
| What is a mutation rate? | Is the probability that a gene will mutat when a cell divides |
| Why is low rate of spontaneous mutation beneficial to a population? | Low rate of spontaneous mutations is beneficial in providing the genetic diversity needed for evolution. |
| Mutant bacteria can be detected by selecting or testing for an altered phenotype. Bacteria only have 1 copy of a gene, compared to eukaryotic organisms which carry 2 copies of a gene. What is the significance of this? | Effects of a mutated gene not masked by the presence of a normal version of the gene, as in eukaryotic organisms. |
| ______________ or direct selection detects mutant cells because they grow or appear different (So, looking for a gain-of-function) | Positive |
| ____________ or indirect selection detects mutant cells because they do no grow or cannot perform a specific function (so, looking for a loss-function) | Negative |
| What is replica planting? | Method in which one or more secondary Petri plates containing different solid selective growth media are inoculated with the same colonies of microorganisms from a primary plate, reproducing original spatial pattern of colonies. |
| _____ test, a test that checks to determine whether or not a mutagenic substance is also carcinogenic an involves the use of mutant bacteria. If the mutant cell is exposed to a substance that is mutagenic, the mutant cell may revert back to a normal cell. | Ames |
| _________ refers to the exchange of genes between 2 DNA molecules to form new combinations of genes on a chromosome. | Genetic recombination |
| Occurs during reproduction only, as in a parent passing their genetic information to their offspring. | Vertical gene transfer |
| Involves the transfer of genes between other microbes of the same generation. (This occurs infrequently, but may involve transformation, conjugation, or transduction) | Horizontal gene transfers |
| ____________, genes are transferred from one bacterium to another as "naked" DNA in solution that occurs naturally among a few genera of bacteria. (So, DNA can be picked up from the environment of nonliving bacteria and does not require direct contact) | transformation |
| is the transfer of genetic information from one cell to another, and requires contact between living cells. | Conjugation |
| occur when DNA is passed from one bacterium to another in a bacteriophage (a virus that infects bacteria) and is then incorporated into the recipient's DNA | Transduction |
| ____________ experiment was an important procedure that demonstrated transformation and how DNA from non-living bacteria could be transferred to living bacteria | Griffith's |
| Conjugation differs from transformation in a few ways. First, it is mediated by a ___________________. Second, it requires _____________ and that conjugation cells must be of _______________________. | -plasmid -cell to cell contact -opposite mating |
| certain bacterial genes are transferred through the use of a bacteriophage(not all traits from the original bacterium are passed to other bacteria)Significant because this is how some bacteria able to acquire harmful characters, like the prod of toxins. | generalized transduction |
| Plasmids are small, extra-chromosomal pieces of DNA found primarily in bacteria that five them some of their special characteristics. __________ are plasmids that carry the genes for sex pili and the transfer of the plasmid to another cell. | Conjugative |
| ___________ are plasmids that encode for the catabolism of unusual compounds. | Dissimilation |
| Some plasmids contain genes that produce toxic proteins that kill other bacteria. | bacteriocins |
| What are resistance factors? Why are they a problem in terms of human health? | -Confers resistance to antibodies. -Heavy mtals or cellular toxins |
| ____________ are segments of DNA that can move from one region of DNA to another and can insert themselves into genes and inactivate them. | Transposons |
| Microbes that grow best at temperatures ranging between -10 to 20 degrees Celsius are called what? | Psychrophiles |
| The optimal pH for most bacteria is | 7 |
| Organisms that are killed in the presence of oxygen are called | Obligate aerobes |
| What is the enzyme called that attaches new nucleotides during DNA replicaton? | DNA polymerase |
| What is the difference between complex and chemically defined media? | In chemically defined media you know the exact amount of each nutrient in the media |
| Which of the following uses light for energy and carbon dioxide as a carbon source? | Photoautotrophs |
| True/False: In prokaryotes, AUG codes for methionine | False; AUG codes for formylmethionine |
| Transcribe the following strand of DNA into RNA: TAC CGC AAG TTA TGC | AUG GCG UUC AAU ACG |
| During the Lac operon, when no lactose is present, the repressor protein binds to: | The operator site |
| Define sterilization | Process that removes all microbial life, including prions |
| True/False: Quats are added to throat lozenges because of their local anesthetic effect | False; phenol or carbolic acid is added |
| The transfer of genes between microbes of the same generation is known as | horizontal gene transfer |
| During which phase of microbial growth is metabolic activity high, but little to no change in cell number is seen? | Lag phase of microbial growth |
| What is the name for the type of mutation that involves single base pairs and is the most common type of mutation? | point mutation |
| What is the name for a substance that inhibits microbial growth, but does not kill the microbe? | Bacteriostatic agent or substance |
| Which of the following is a halogen that is frequently used as an antiseptic? | Iodine |
| True/False: During anaerobic respiration, electrons are donated to an organic molecule as the final electron acceptor. | False; donated to an inorganic molecule other than oxygen |
| True/False: Reducing media is used to grow organisms called cannophiles. | False; reducing media is used to grow obligate anaerobes |
| A culture medium on which only gram-positive organisms grow and a yellow halo surrounds Staphylococcus aureus colonies is called a(n) | Selective Medium & Differential Medium |
| ______________ is a physical method of controlling microbial growth that causes plasmolysis of cells due to the hypertonic environment that is created | osmotic pressure |
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