sample bace.docx

Why must the technicians practice aseptic techniques when culturing cells? To ensure they are growing pure cultures of their desired cells To ensure they are using the correct media to grow their desired cells To ensure they are incubating their cells at the proper temperature To ensure they are a...

Why must the technicians practice aseptic techniques when culturing cells? To ensure they are growing pure cultures of their desired cells To ensure they are using the correct media to grow their desired cells To ensure they are incubating their cells at the proper temperature To ensure they are adding the correct supplements to their media Which of the following techniques destroys all microorganisms? Disinfection Cleansing Sanitation When using a microscope on the highest power objective, which focus knob should you use? Coarse Fine A solution with a pH of 3.0 is how many times more acidic than a solution with a pH of 6.0? 10 100 1000 10,000 Salt (such as sodium chloride or sodium acetate) is commonly used in procedures to extract plasmid DNA. Which of the following best describes the role of the salt? The positively charged sodium ions dissolve cell organelles The positively charged sodium ions provide cushion allowing for faster centrifugation The positively charged sodium ions neutralize the negatively charge on the DNA The positively charged sodium ions degrade the bacterial cell wall Why is plasmid DNA is purified using anion exchange column chromatography? DNA is positively charged, binds to the negatively charged resin, and is eluted with increasing salt DNA is negatively charged, binds to the positively charged resin, and is eluted with increasing salt DNA has a natural affinity for most columns Plasmid DNA is small enough to bind to the column A technician is testing the purity of DNA sample using a spectrophotometer. He gets a 260 nm reading of 0.51 au, and a 280 nm reading of 0.65 au. Recalling that the preferred range for the value is 1.8-2.0, is the purity of the sample acceptable? Yes No The answer cannot be determined from the information provided Referring to the gel below, what is the approximate size of band B? Approximately 140 base pairs Approximately 1,400 base pairs Approximately 14,000 base pairs None of the above Whan using an acrylamide gel for protein electrophoresis, it is best to use a higher percentage of acrylamide to resolve smaller proteins, while large proteins are best resolved on low-percentage gels. True (the smaller the chunks of DNA, the more dense you want the gel to be in order to get the different sizes to resolve (separate) from each other). Match the following steps in PAGE with the correct purpose of the step: Staining with Coomassie Blue – To visualize proteins after PAGE Adding loading dye to protein samples – To facilitate loading samples into wells, and to monitoring sample migration Adding a molecular weight standard to an empty well – AKA using a ladder – To determine the relative size of the samples run on the gel Adding SDS (sodium dodecyl sulfate AKA unravels proteins) to the sample buffer and the PAGE running buffer – To coat the sample proteins with a negative charge, and denature them Your supervisor asks you to run a PCR reaction with products ranging in size from 200-400 base pairs. To confirm the reaction outcome on an agarose gel, which of the following strategies will give you the best resolution of the PCR products? Use a higher percentage of agarose and a higher running voltage Use a higher percentage of agarose and a lower running voltage (forcing the molecules through the pores, and a low voltage to avoid melting the gel) Use a lower percentage of agarose and a higher percentage of voltage Use a lower percentage of agarose and a lower percentage of voltage In agarose gel electrophoresis, the negative electrode terminal is located: At the bottom of the gel (furthest from the well) At the top of the gel (closest to wells) Assume the DNA in lane 3 in the image below was loaded on the gel after it was digested with the restriction enzyme EcoRI. If the DNA was originally a plasmid, and the restriction enzyme digest was complete, how many EcoRI sites are in the plasmid? 0 1 2 3 4 A technician is given a sample of DNA from a PCR reaction and a sample of uncut plasmid. The PCR product contains a gene of interest that the technician's supervisor wants cloned into the plasmid. The technician uses software to determine which enzymes she can use for each sample below is a list of restrictions multiple cloning site and a list of restriction enzymes that cut on both sides of the gene of interest, but not in the gene of interest. Restriction enzymes that cut on BOTH sides of the gene of interest in the PCR product: - BamHi - EcoRI - HindIII - Pstl - Sacl Restriction enzymes that cut once in the plasmid’s multiple cloning site: - Alul - Bgll - Dral - EcoRV - HindIII Assuming all of the restriction enzymes cut sites are unique, which restriction enzyme should the technician use to digest the DNA? BamHi EcoRI HindIII Sacl In recombinant DNA technology, DNA ligase is used to rejoin which of the following bonds in DNA? Carbon Phosphodiester Hydrogen Nitrogen A restriction enzyme digestion reaction contains which of the following reagents? DNA, water, dNTPs, Restriction Enzyme DNA, Water, Buffer, dNTPs DNA, Water, Buffer, Restriction Enzyme DNA, Water, Buffer, Restriction Enzyme Place the following steps of a general protocol for genetic engineering in the correct chronological order. 1. Isolate the gene of interest 2. Paste/clone gee of interest into vector 3. Transform host cells with vector 4. Grow recombinant cells 5. Purify gene product When performing a transformation ice cold calcium chloride makes the cells “chemically competent” (AKA makes little holes inside of the cell membrane cell wall through which the DNA can enter so they make it more permeable to DNA). Which of the following is the primary feature of chemically competent cells? They are more permeable to DNA They are more permeable to proteins They are less susceptible to infection They are less susceptible to lysis Which of the following techniques should be used to amplify specific DNA sequences? PAGE (polyacrylamide gel electrophoresis – for proteins) Bradford assay (quantify how protein there is in a solution) PCR ELISA (antibody test – test for certain protein) Place the following steps in order to best describe the sequence of a PCR cycle. 1. The mixture is heated to denature the double stranded DNA 2. The primers hybridize to the target DNA DNA polymerase extends the primers to make a copy of the target DNA Match the type of chromatography to the property it uses to separate proteins. Gel-Filtration/Size Exclusion Chromatography (SEC) – Separates proteins based in size Ion Exchange Chromatography (IEC) – Separate proteins based on charge Affinity Chromatography – Separate proteins based on unique functional groups Hydrophobic Interaction Chromatography (HIC) - Separate proteins based on solubility in water Many biopharmaceuticals must go through a purification process to separate them from cellular debris, media and other components used during cell culture. Which of the following is a commonly used technique to separate proteins from complex mixtures? Microarray ELISA Chromatography PCR A technician is asked to verify the presence of a protein of interest after a production run. Following purification via column chromatography, a fraction from the column is run on an SDS-PAGE, and a band appears at the expected molecular weight. Which of the following techniques listed is the best way to verify that the band is the purified protein of interest? Run a Bradford protein assay with a sample of the fraction Run a second SDS-PAGE with a sample of the fraction Run a Western blot with a sample of the fraction Run a PCR reaction with a sample of the fraction *Can do an ELISA to see if the right protein - could use an antibody that only sticks to that protein. When an ELISA is done on an gel = Western blotting Diagnostic immunoassay for infectious diseases, such as strep throat, are commonly used by physicians to quickly diagnose patients. These immunoassays utilize the reaction of antibodies to which of the following from a patient’s sample? B cells Enzyme-binding sites Antigens from the pathogen Plasma cells Place the general steps of generating a monoclonal antibody in order. 1. Inject/Immunize an animal with antigen of interest 2. Repeat immunization of animal with antigen of interest to boast immune response 3. Collect serum 4. Isolate B cells 5. Fuse B cells to tumor cells (create hybridoma) 6. Isolate hybridoma of interest The difference between a direct ELISA and an indirect ELISA is that the conjugated enzyme to be detected is linked to the primary antibody in a/an __________ ELISA, where as the detection enzyme is linked to the secondary antibody in a/an ________ ELISA. Direct, indirect Indirect, direct Both antigens and antibodies can adhere to the wells of ELISA plates through non-specific biding to plastic. True Which type of ELISA is the most appropriate to determine the concentration of a specific antigen in a sample? Qualitative ELISA (is it there or is it not) Quantitative ELISA (how much is there) Either will work Sandwich ELISAs are commonly used in commercial diagnostic kits because of the increased accuracy of the assay. Which of the following contributed to the increased level of accuracy? (bread = antibodies, inside = antigen) The antigen must be recognized by both a primary and a secondary antibody for the assay to give a positive result The antigen must be recognized by two primary antibodies for the assay to give a positive result The antigen must be recognized by two secondary antibodies for the assay to give a positive result The antigen must be recognized by two primary and two secondary antibodies for the assay to give a positive result Which of the following is typically measured using a spectrophotometer set at a wavelength of 600 nm? The number of bacterial colonies on a plate of media The concentration of bacteria in a suspension The concentration of DNA in a sample The number of DNA base pairs in a sample Preventative maintenance (PM) and calibration on laboratory equipment is scheduled according to which of the following? Based on the equipment manufacturer’s suggestion Based on how often the equipment is used Based on the company’s SOPs for PM and calibration All of the above How is the number 0.000052 correctly written in scientific notation? 0.000052 5.2 x10 -5 5.2 x10 5 None of the above What is 0.9857 rounded to three significant digits? 0.100 0.986 0.985 0.990