After you have received your PhD in molecular genetics, and become an expert in
ID: 9437 • Letter: A
Question
After you have received your PhD in molecular genetics, and become an expert in manipulating DNA, a buddy offers you a ride into the past in his newly developed time machine. You see your chance to become famous by using our modern recombinant DNA technology to “prove” a fact about DNA that was initially disputed in the past. So you load up your lab case, travel back in time, and dazzle the folks with a brilliant proof of a controversial molecular genetic topic related to the structure or function of DNA (forget any consideration of ethics for this question). Please tell me 1) what controversy you chose to solve, 2) what technique you used to come up with incontrovertible results, 3) what these results would be and how you would interpret them to solve the DNA dilemma, and 4) two of the items/reagents/skills that you would need to take back with you to do your dazzling experiment.Because you got into trouble with the Time Police after the last question, you have to do some penance by serving as an undercover agent in the city of EukaryoticCell. After being Galeezled down to the right size, you are given binoculars and a notebook. Your task is to observe the nucleus within EukaryoticCell and report back 10 observations about the inhabitants of this city. And you better not try to just make things up – the Mitochondrial Muscle Men are watching you!
Explanation / Answer
1) I would settle the "homosexual" gene debate by proving it does exist, or at least it is a "switch" that can get turned on during DNA translation via the supposed "non-coding" regions. 2) through SDS Page and electrophoresis, as well as some nifty presentation gadgets. 3) The experiments would prove that the gene is X-Linked and that it turns on when the hormone levels in the mother are low during the fetus's testes formation. 4) PCR machines, and electrophoresis equipment. Observations of the nucleus include; 1- It has two concentric lipid bi-layer membranes around it. 2- The outer membrane is contiguous with the endoplasmic reticulum. 3- It has filaments sticking both outside and inside. 4- There are items moving in and out of the membranes through nuclear pores. 5- The inside of the nucleus is packed full of DNA. 6- There is a dark spot visible from the outside called the nucleolus. 7- Only certain items can get imported into the nucleus and they must have a NLS or nuclear localization sequence (a cluster of five amino acid residues ot two short basic amino acid residues) 8- Items coming out of the nucleus must have a NES or nuclear export signal (a Leu-rich sequence) which bind to exportins to leave the nucleus. 9- The nucleolus seems to not be membrane bound. 10- The nucleolus is the site of ribosome bio-synthesis, rRNA transcription, and assembly of ribosomal proteins onto rRNA.