Check out today’s Step 1 Qmax Question Challenge.
Know the answer? Post it below! Don’t forget to check back for an update with the correct answer and explanation (we’ll post it in the comments section below).
A 23-year-old female patient who is a carrier of sickle cell trait presents to the clinic. In this patient’s case, the single base-pair mutation for sickle cell anemia destroys the MstII restriction enzyme recognition site represented by an asterisk (*) in the image below. The restriction enzyme-binding sites are shown as arrows on the map. DNA is taken from this carrier patient and is treated with MstII and run on an electrophoresis gel. The DNA is then hybridized with a labeled probe that binds to the gene in the position shown on the map.
In the Southern blot shown to the right in the image above, which lane represents the patient?
Want to know the ‘bottom line?’ Purchase a USMLE-Rx Subscription and get many more features, more questions, and passages from First Aid, including images, references, and other facts relevant to this question.
This practice question is an actual question from the USMLE-Rx Step 1 test bank. For more USMLE Step 1 prep, subscribe to our Flash Facts and Step 1 Express video series. Score the best deal on all three products with a Step 1 Triple Play Bundle.