1- A new beetle species has arrived in Ohio and ate the wheat, destroying much o
ID: 92296 • Letter: 1
Question
1- A new beetle species has arrived in Ohio and ate the wheat, destroying much of the harvest. Research in lab has found that a toxin from the bacterial species Bacillius subtilius can kill the beetle when ingested. You are able to make recombinant DNA containing a plant expression vector and the toxin gene from Bacillius subtiliu. This toxin gene is transcribed and translated in plant cells in the lab. Before introducing this recombinant DNA into corn plants, what main concern do you need to first address?
A) Do we have the technology to express the toxin in this plant cell?
B) Will this gene escape the corn plant and the DNA inserts itself into other plant species?
C) Will the toxin harm humans/livestock when they eat the corn?
D) Will introfuction of the recombinant DNA select for naturally resistent weeds?
E) other
2- You are working on influenza virus infection and want to know if the isg15 gene in mice protects against a particular iinfluenza viru strain? You ask if the isg15 decreases influenza viral replication. You want to silence the expression of the isg15 gene in cells, and you only need the gene silence for a short time (24-48hours). What is the fastest method you would use to silence the isg15 gene?
A) Polymerase chain reaction (PCR) for the isg15 gene
B) Make a ecombinant DNA molecule conyaining the isg15 gene that can be expressed in mouse cells
C) Use homologous recombination to knock out the isg15 gene and then grow up those cells
D) Use a short interfering (si)RNA to the isg15 gene
E) Use a microarray to look at the isg15 levels
3- A mutation in the TATA box would:
A) allow more transcription factors to bind to the DNA
B) prevent RNA polymerase from bindng to the DNA
C) prevent alternative spilcing
D) Mutate the silencer sequence of the DNA
E) Allow RNA polymerase to start transcription
4- If a genes template strand's DNA sequence is 3'-TGA-5', the codon sequence is ___ and the anticodon sequence is ___.
A) 5'-ACU-3' and 3'-UGA-5'
B) 5'-ACT-3' and 3'-TGA-5'
C)5'-UGA-3' and 3'-ACU-5'
D)5'-ACU-3' and 3'-ACU-5'
E)5'-UGA-3' and 3'-UGA-5'
Please help and explain why! Thanks!!
Explanation / Answer
The correct answer of question 1 is C) To check whether the toxin is affecting humans/livestocks feeding on corn.
The presence of toxin in plant cell to kill the bettles, the transfer of gene from corn plant to effect other plant species or the selection of the recombinant DNA for resistent weeds. All of these have second priority. Hence, option A), B), D) and E) are incorrect.
The main concern is always to check whether the toxin we are introducing will effect the plant (in the case corn), and the human/livestocks will be able to eat it or not.(C) is the correct answer.
The correct answer for question 2 is D) using siRNA gene silencing method to silence isg15 gene.
Polymerase chain reaction will amplify the gene making more copies instead of silencing, recombinant DNA is being used for its expression, after homologous recombination knockdown of gene and then growing the cell the gene will be absence and microarrays will only help in telling the expression how much level of gene is being expressed.
Hence, option A), B), C) and E) are incorrect.
The siRNA is a gene silencing method used to silence the gene by degrading the mRNA and stops the protein formation. (D) is the correct answer.
The correct answer of question 3 is B) The mutation will prevent binding of RNA polymerase to DNA.
The mutation will not allow more transcription factors to bind, mutation will not effect alternative splicing, it will also not mutate the silencer DNA sequence and the RNA polymerase initaiting transcription is a normal process, but after mutation tata box it will not happens.
Hence, option A), C), D) and E) are incorrect.
The mutation in tata-box will result into not binding of tata binding protein so there will be no formation of pre-initiation complex to which RNA polymerase can bind and start transcription. So, the RNA polymerase will not bind to DNA and start transcription. (B) is the correct answer.
The correct answer of question 4 is A) 5'-ACU-3' and 3'-UGA-5'
The option D) and E) are not complimentary to each other so, incorrect.
B) option is incorrect because anticodon sequence will have U instead of T,
The complimentary to 3'-TGA-5' is 5'-ACT-3' whose coding sequence in mRNA will be same but the T will be replaced by U. So, option C) is incorrect.
The coding sequence then will be 5'-ACU-3' and the anticodon sequence will be complimentary to it which is 3'-UGA-5'. (A) is the correct answer.
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