transposon question

[theonlytycrane]

Which of the following is an accurate description regarding the activity of transposons?

A) If a single transposon inserts into the promoter or regulatory region of a protein coding gene, protein levels will decrease.

B) If a single transposon inserts into protein-coding DNA, the protein-coding region will be disrupted and proteins levels will likely decrease.

C) Two transposons in the same orientation can cause chromosomal inversion, where a section of a chromosome is flipped into the reverse orientation.

D) Two transposons in the opposite orientation can cause chromosomal deletions and translocations, which are both types of chromosomal rearrangements.

The given answer is B. Is this a case where B is a better answer than A?

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[NextStepTutor_2]

Which of the following is an accurate description regarding the activity of transposons?

A) If a single transposon inserts into the promoter or regulatory region of a protein coding gene, protein levels will decrease.

B) If a single transposon inserts into protein-coding DNA, the protein-coding region will be disrupted and proteins levels will likely decrease.

C) Two transposons in the same orientation can cause chromosomal inversion, where a section of a chromosome is flipped into the reverse orientation.

D) Two transposons in the opposite orientation can cause chromosomal deletions and translocations, which are both types of chromosomal rearrangements.

The given answer is B. Is this a case where B is a better answer than A?

Hi @theonlytycrane !

I am thinking the reasoning they are going for is that transposon insertions near promoter regions, (segments of DNA that used to initiate gene transcription), can lead to over-activity of genes. Activation is usually due to de-repression or introduction of a complete or partial promoter located within the element.

there are a few papers out there that may be of interest: http://www.ncbi.nlm.nih.gov/pubmed/2830468

Hope this helps, good luck!

 

[jaramaiha]

Although this thread is rather old, transpons can insert/ remove themselves within the genome. To answer your question, if it did enter within a region that typically codes for a protein it would lead to a nonsense codon being read. Think of mutations within the genome. Protein production is highly regulated, so if a single residue is changed it could code for missense/ nonsense proteins. Now if an entire transpon is inserted within that same region it would not only lengthen the polypeptide chain, but throw off the entire production leading to a decrease in production of the protein in question.