April Hallock SCIN 211

.pdf

School

American Public University *

*We aren’t endorsed by this school

Course

211

Subject

Biology

Date

Jan 9, 2024

Type

pdf

Pages

Uploaded by SuperGalaxy641

12/17/23, 7 : 06 PM Transgenic Fly Virtual Lab Lab Notebook Page 1 of 1 https://media.hhmi.org/biointeractive/vlabs/transgenic_fly/content/sect1_part6_quiz_results.html Part 6: Quiz answers 1. How is light produced by the transgenic flies? A. The same way that light is produced in fireflies. B. The transgenic flies have eaten a substance that produces light. C. Transcription of the transgene results in production of luciferase, which acts on luciferin. D. Turning on the room lights causes light to be produced by the flies. Correct! Your answer: C. C. CORRECT. Transcription of the transgene results in production of luciferase, which acts on luciferin. (Click here for more details.) 2. Maximal light output from the transgenic fly occurs when the promoter of which gene is activated? A. period B. luciferase C. mini-white D. timeless Correct! Your answer: A. A. CORRECT. In the virtual lab experiment, only the period promoter is adjacent to the luciferase gene. When the period promoter is activated, luciferase gene transcription is turned on, producing luciferase mRNA. Luciferase mRNA is translated into luciferase protein, which acts on luciferin (in the fly's diet) to produce light. View lab status and quiz summaries

12/17/23, 6 : 53 PM Transgenic Fly Virtual Lab Lab Notebook Page 1 of 2 https://media.hhmi.org/biointeractive/vlabs/transgenic_fly/content/sect1_part4_quiz_results.html Part 4: Quiz answers 1. After completing a transgenic injection experiment, only white-eyed progeny result. Which of the following situations could explain the result? A. You did not inject enough embryos. B. You accidentally broke the glass needle and had to replace it with a new one in the micromanipulator. In the meantime, the embryos continued to develop, and all were more than 60 minutes old when you began the injections. C. All your injections missed the germ cells in the posterior region of the embryos. D. All the above. Correct! Your answer: D. D. CORRECT. All the above. A. INCORRECT. Even if you inject a few embryos correctly, all these embryos can die. A second possibility is that surviving embryos may have been injected with construct DNA but that DNA may not have integrated into the embryos' DNA. Both possibilities could result in only white-eyed progeny. Therefore, it is important to correctly inject as many embryos as possible. B. INCORRECT. All reagents and supplies need to be prepared ahead of time so the embryos can be injected promptly when they are less than 30 minutes old. C. INCORRECT. To obtain red-eyed flies, the DNA must be injected into the cells that will become germ cells, located at the posterior end of the embryo. 2. All the injected embryos that have grown to adulthood have white eyes. They are mated with wild-type flies that also have white eyes. How is it possible that some progeny will have red-eyes? A. Red-eyed flies contaminate the experiment. B. Progeny with red-eyes are the result of matings in which the germ cell from one parent contains the transgene. C. A mutation occurs that produces red eyes. D. Progeny with red eyes occur in flies raised in constant darkness. Correct! Your answer: B. B. CORRECT. Progeny with red-eyes are the result of matings in which the germ cell from one parent contains the transgene. A. INCORRECT. These experiments are conducted under carefully controlled conditions such that no contamination is possible. Print

12/17/23, 6 : 50 PM Transgenic Fly Virtual Lab Lab Notebook Page 1 of 2 https://media.hhmi.org/biointeractive/vlabs/transgenic_fly/content/sect1_part3_quiz_results.html Part 3: Quiz answers 1. Injected fly embryos fail to survive for all of the reasons below except A. fluid loss due to wound at injection site B. injection of too much fluid, causing embryo to explode C. embryo is too young to tolerate injection D. embryo becomes too dry Correct! Your answer: C. C. CORRECT. Younger embryos actually tolerate the procedure better than do older embryos. A, B, and D. INCORRECT. Excessive fluid loss, injecting too much DNA solution such that the cell explodes, and embryos drying out all may result in the death of the embryo. 2. When injecting flies with the construct DNA, which of the following steps will help increase the chances that transgenic progeny are produced? A. Inject a large volume of DNA solution. B. Inject many embryos. C. Inject into the outermost embryonic membrane. D. Destroy all older embryos. Correct! Your answer: B. A. INCORRECT. Injecting too large a volume of DNA solution will cause the embryo to explode, as illustrated in the interactive window if the mouse button is clicked more than once. B. CORRECT. Injecting many embryos will increase the likelihood that transgenic progeny are produced. However, the injection must occur in a specific time window during embryonic development, limiting the number of embryos that can be injected at once. C. INCORRECT. The needle must penetrate all embryonic membranes and enter the interior region of the embryo where cells will become germ cells. D. INCORRECT. The researcher may destroy older embryos, because these embryos are too old to incorporate the injected DNA into their cells. This procedure limits the number of adults with non transgenic germ cells, reducing the number of white-eyed non transgenics to sort through in later steps. However, this procedure does nothing to improve the likelihood of obtaining transgenic progeny.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version