Step I nbme 3 or 4

[2cr8tive]

writing my exam end of july. ive done form one and two, 221, 224 respectively. i want to see where i stand and write one more next monday, which form do you recommend 3 or 4? someone here said 3. and i hear there is a lot of molecular biology in both, so is kaplan enough for those or should i go through the high yield quickly? thanks

 

[BrisketAttack]

do 3. there's some molecular, but that stuff so silly-detailed that you just have to have an underlying sense of the concept, then reason your way to an educated guess. very few of the molecular scenarios will be something you've seen before, but the concept might be somewhat fundamental (e.g. northern blot to detect gene expansion in huntingtons).

 

[doctorFred]

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shouldn't that be a southern blot (DNA)?

 

[BrisketAttack]

honestly, i'm not sure. i think both would work, since they're looking at nucleic acid, both use a probe, and the expansion is within an exonic sequence. i don't see why northern wouldn't work.

 

[2cr8tive]

do 3. there's some molecular, but that stuff so silly-detailed that you just have to have an underlying sense of the concept, then reason your way to an educated guess. very few of the molecular scenarios will be something you've seen before, but the concept might be somewhat fundamental (e.g. northern blot to detect gene expansion in huntingtons).

any reason your recommending 3 over 4?

 

[Instatewaiter]

honestly, i'm not sure. i think both would work, since they're looking at nucleic acid, both use a probe, and the expansion is within an exonic sequence. i don't see why northern wouldn't work.

technically northern will work but I think southern is more often used (edited)

northern is more often used to see which genes are expressed and where they are expressed. For example if you want to see if a certain gene is expressed in brain, kidney, liver etc you run a northern. They all have the DNA but northern tells you where and when the genes are expressed.

 

[BrisketAttack]

technically northern will work but I think southern is more often used because some of the huntingtin protein is sequestered or ubiquitinated pretty quickly so it is harder to comeby the mRNA rather than the DNA

northern is more often used to see which genes are expressed and where they are expressed. For example if you want to see if a certain gene is expressed in brain, kidney, liver etc you run a northern. They all have the DNA but northern tells you where and when the genes are expressed.

whether or not a protein is ubiquitinated has no bearing on the outcome of a northern blot reaction. northern blot looks at mRNA, while western blot looks at protein. I can see how ubiquitination, and subsequent degradation of the protein product, could potentially affect western blot results, but the northern would be unaltered. I stand by my original claim that a northern is an appropriate diagnostic measure for huntingtons.

 

[BrisketAttack]

any reason your recommending 3 over 4?

I've heard 3 is harder, and slightly more predictive. this is just what I've heard from 4th year friends, and several people on SDN, so take it for what it's worth.

 

[Instatewaiter]

whether or not a protein is ubiquitinated has no bearing on the outcome of a northern blot reaction. northern blot looks at mRNA, while western blot looks at protein. I can see how ubiquitination, and subsequent degradation of the protein product, could potentially affect western blot results, but the northern would be unaltered. I stand by my original claim that a northern is an appropriate diagnostic measure for huntingtons.

Yeah you're totally right. I have no idea where I came up with that.