代做Bio99 Practice Quiz #3帮做R编程

日期：2024-05-22 03:41

Bio99 Practice Quiz #3

You are studying the Drosophila Tral gene, whose protein product is involved in mRNA localization.  You want to examine the regulation of Tral expression in flies.

1.  To facilitate your study, you create a GFP tagged version of Tral.  Which one of the following is not a step you would perform. to accomplish this?

A. PCR the Tral gene from Drosophila genomic DNA.

B. Digest the PCR product and a GFP-containing plasmid.

C. Add the insert and vector together and add DNA ligase.

D. Transform. the ligation mixture into Drosophila.

E. All of the above would be performed.

2.  For this cloning, we need to include a                    promoter in the plasmid.

A. Bacteria

B. Drosophila

C. Neither

D. Both

3.  Next, you want to examine whether H3 histones are acetylated at lysine 9 around the Tral gene.  If they are acetylated, the DNA will likely be                        compacted.  

A. Loosely

B. Tightly

4. Which technique(s) would allow you to determine the impact of the acetylation (in question 3) at the Tral gene.  Select all that apply.

A. Quantitative RT PCR

B. EMSA

C. Immunoprecipitation

D. Western blot

E. DNA footprinting

5.  You also speculate that various transcription factors could be regulating Tral expression.  One such factor is Snail.  

a.  If Snail is a transcription factor activating Tral expression, which of the following could potentially be a function of Snail? Select the best answer.

A. Inhibit the binding of RNA polymerase at the Tral promoter.

B. Recruit a histone modifying protein that opens up the chromatin at the Tral gene.

C. Recruit DNA helicase at the origin of replication. 

b.  You want to determine whether Snail binds to the Tral promoter DNA.  Which technique(s) would allow you to determine whether this occurs.  Select all that apply.

A. Quantitative RT PCR

B. Immunoprecipitation

C. Western blot

D. DNA footprinting

c.  Using this experiment above, you find that Snail actually binds 10kb downstream of the Tral promoter.  Do you believe this result?  YES or NO.  Explain.

A. Yes, because proteins are much larger than nucleotides.

B. Yes, because DNA in the cell is folded.

C. No, because RNA polymerase wouldn’t be able to bind to both Snail and the promoter.

D. No, because our genome is smaller than 10kb.

d.  Now you want to determine the effect of the loss of Snail on Tral-GFP expression.  If Snail is an activator of transcription, draw/describe the expected results from a:

i.  Northern blot

ii.  Q-RT PCR reaction

iii.  Fluorescence microscopy experiment

iv.  Western blot

6.  From some of the experiments above, you determine that Tral actually undergoes alternative splicing, producing 2 different RNAs/proteins.  Which of the following is/are potential benefit(s) of Tral alternative splicing?  Select all that apply.

A. Protection against mRNA degradation

B. Production of multiple proteins from a given gene

C. Export of Tral mRNA from the nucleus

D. Increased fluorescence due to modification of the Tral promoter sequence

7.  Because this experiment hasn’t gone on for long enough, you want to determine whether Tral expression is regulated by micro RNAs.

You believe that miR-277 is inhibiting Tral-GFP translation (but not affecting mRNA stability).  Which of the following experimental results would you expect to see if this is the case? Select all that apply.

A. Tral-GFP mRNA levels are the same regardless of whether the cell expresses miR-277.

B. Tral-GFP protein levels are the same regardless of whether the cell expresses miR-277.

C. Tral-GFP mRNA levels are lower when the cell expresses miR-277.

D. Tral-GFP proteins levels are lower when the cell expresses miR-277.