NBME 15 questions

[codebluewinniethepooh]

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Hey all,
I have some questions I got wrong, I appreciate if you guys can help with an explanations:
1- section 4: q 13: A 65 yrs old women her DEXA shows decreased bone density, what is her osteoblast, osteoclast activities and receptor activator of nuclear factor kB ligand concentration?
I think it is decrease osteoblast activity, increase osteoclast activity, and the receptor activator of RANKL is decreased because the osteoblast activity is decreased. what do you guys think?
2- An investigator is studying H.pylori, where the original strand has eight consecutive cytidines while the isolate has nine:
cross over, DNA excision repair, slipped strand mispairing, thymidine dimer formation, transposon insertion?

I appreciate your input,

 

[chromuffin]

Hey all,
I have some questions I got wrong, I appreciate if you guys can help with an explanations:
1- section 4: q 13: A 65 yrs old women her DEXA shows decreased bone density, what is her osteoblast, osteoclast activities and receptor activator of nuclear factor kB ligand concentration?
I think it is decrease osteoblast activity, increase osteoclast activity, and the receptor activator of RANKL is decreased because the osteoblast activity is decreased. what do you guys think?
2- An investigator is studying H.pylori, where the original strand has eight consecutive cytidines while the isolate has nine:
cross over, DNA excision repair, slipped strand mispairing, thymidine dimer formation, transposon insertion?

I appreciate your input,

1. What is important here really is understanding RANK-L. RANK-L is found on the osteoblasts and works to activate osteoclasts by binding to RANK on the osteoclast. This binding triggers osteoclasts activity. So osteoblast activity decreased, osteoclasts activity increased, RANK-L increased (because more osteoclasts are getting activated).

2. I can't givenmuch input on this because I haven't studied biochem yet but the answer is slipped strand. The idea is that the excess cytidines trip everything up and can lead to an extra cytidine.