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LS23L FINAL EXAM Q/A With Verified Solutions 2023
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LS23L FINAL EXAM Q/A With Verified Solutions 2023
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LS23L FINAL EXAM Q/A What event is MOST responsible for causing the conformational change in the lac repressor of E. Coli? a. the increase in cell density over time causes their to be more lac operons b. enough time has passed since the end of mitosis and the cell is ready to begin transcription c. ONPG interferes with the lac repressor's ability to bind the operator d. the presence of glucose causes a conformational change in RNA polymerase which allows it to carry out transcription e. lactose allosterically binds to the lac repressor, causing conformational change Correct Answer: Which of the following is FALSE about any possible ingredients that can be used in the Sanger Sequencing method? Correc t Answer: The four types of dideoxynucleotides are using as the building blocks of the new sequences which extend the newly synthesized strands, What event is Most responsible for causing the conformational change in the lac depressor of E. Coil? Correct Answer: Lactose allosterically binds to the lac repression, causing a conformational change Which of the following represent the same orientation in humans? Correct Answer: Posterior and Dorsal If one wants to measure B -galactosidase activity under diffe rent conditions, it is important to take cell density into account primarily because: Correct Answer: if cell density were not measured, one would not know whether more enzyme is being produced because of upregulation, or because of there just being In the DNA extraction procedure, chelex was added to the sample of your cheek cells. What was the reason for its addition and what mechanism was used to disrupt the cell walls of your cheek cells? Correct Answer: Chelex binds to Magnesium, a cofactor needed for DNase, an enzyme that degrades DNA. The sample was heated to disrupt the cell membrane Which of the following statements is considered incorrect? a. The enzyme beta -galactosidase catalyzes the hydrolysis of lactose into galactose and glucose b. If all t he enzymes that a cell will possibly need are produced all the time, then a cell will waste a lot of energy c. Lactose is the only energy source that bacteria can utilize d. When lactose is present, it binds to the repressor region of the lac operon, ther eby causing a conformational change of the repressor and making it fall off from the operator region e. The transcription of beta -galactosidase is regulated by the presence or absence of lactose in the environment Correct Answer: c. Lactose is the only ene rgy source that bacteria can utilize In the Sanger method of DNA sequencing, DNA synthesis stops when a _____________ is encountered. Correct Answer: Dideoxyribose base Which of the following is TRUE regarding DNA sequencing and amplification: a. Taq po lymerase is resistant to denaturation caused by heat b. Mitochondrial DNA is amplified using the Chelex technique c. Chelex prevents DNA degradation by binding Ca2+ d. PCR is an in vivo DNA synthesis reaction repeated many times e. Mitochondrial DNA can trace paternal lineage Correct Answer: a. Taq polymerase is resistant to denaturation caused by heat The mass of a protein as determined by gel filtration is 270kDa. SDS -PAGE analysis of this protein could produce: Correct Answer: two bands -- 100kDa and 35kDa An electron microscope is different from a compound microscope in all of the ways listed below except: a. an electron microscope cannot be used to look at living cells b. an electron microscope has a higher magnification c. an electron microscope uses beams of electrons to visualize an image d. an electron microscope is more appropriate for analyzing living prokaryotic cells e. The two types of microscopes are exactly the same, just one is less expensive Correct Answer: d. an electron microscope is more appropriate for analyzing living prokaryotic cells The ______________ is the structure that releases bile, which is released into the ______________ where the majority of that fat is emulsified. Correct Answer: gallbladder; small intestine During the dissection of the rat in lab, which part of the brain was observed? Correct Answer: Pons Which directional term is incorrect? a. Ventral is toward the floor b. Lateral is toward the side c. Dorsal is toward the back d. Anterior is toward the front of the body e. Distal is located away from a point of reference Correct Answer: a. Ventral is toward the floor What is the major difference between a slide containing lung tissue and a slide containing adipose tissue? Correct Answer: The lungs are denser than adipose tissue in order to withstand respiration Why were fish used in the Metabolism experiment? Correct Answer: Fish have a variable body temperature and metabolic rate that are influenced by the surroundings The correct seque nce of digestive organs from the anterior end to the posterior end of a rat is: Correct Answer: duodenum, large intestine, rectum The purpose of performing the Student's t -test and finding the p -value is to: Correct Answer: Determine that the difference in means between two samples is statistically significant The Spectrophotometer produces a plot of: Correct Answer: The absorption spectrum While pipetting for an experiment, your P20 shows the values 1, 2, 8 from top to bottom respectively. How much did you pipette? Correct Answer: 12.8 microliters Which of the following is incorrect regarding Electrophoresis? a. Electrophoresis c onfirms the presence of purified DNA visually and confirms the DNA purity b. Gel electrophoresis can determine whether the amplified DNA is the correct size or composed primarily of primer -dimer c. The polyacrylamide gel is used in the DNA analysis lab d. When the unknown DNA is compared with markers of known molecular weights and quantity, the relative intensity of unknown DNA to the marker DNA can be estimated e. In an agarose gel, EtBr intercalates between DNA base pairs and fluoresces under UV light Co rrect Answer: a. Electrophoresis confirms the presence of purified DNA visually and confirms the DNA purity For the biochemical assay of B -galactosidase activity, why is the absorption at 600nm greater at 70 minutes compared to 20 minutes? Correct Answer: There are more cells What elements within a haplogroup are found to be similar? Correct Answer: haplotypes Why would a scientist choose to use polyacrylamide instead of agarose for gel electrophoresis? Correct Answer: He wants to separate DNA with very small size differences. What is a molecular clock? Correct Answer: The rate of change of mutation of a particular gene. Which of the following is INCORRECT? a. Difference in pore size allows one to resolve smaller fragments on agarose gels than on acryla mide gels. b. Polypeptides were visualized via fluorescence of the FITC tag, while DNA fragments were visualized using ethidium bromideThe benefits of buying summaries with Stuvia:
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