AAMC 11 Ebola passage - dafuq is this?

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My girlfriend (a neurobio major) told me she's seen graphs like this plenty of times. I unfortunately wasn't a bio major, and have no idea how to read these graphs. Never seen it in my life. She wasn't really helpful, either, since she was having a hard time with this passage as well (I made her do it). What the hell is going on! If it wasn't for this passage, I would have gotten in the 11-12 range. Can someone walk me through it please?

Any help would be appreciated.

(+/- +/+ what the hell is this)

Well the +/+ notation at the top is the alleles for the gene in question (CatB or CatL). +/+ means two copies of the wildtype, while -/- means both copies have been knocked out; not relevant here, but +/- would have one functional copy.

So you break up the graph by the allelic populations indicated by the brackets along the top. Then you compare what happens when you introduce new genes, as labeled along the bottom, to the WT control on the left.

I WAS a bio major, and I remember doing a double take at this passage, it was a handful.

Thanks for your response.

I did another practice problem, and the +/- is still tripping me up. This is from princeton - "Since the bacteria can grow without Arginine, it is Arg+"

What the hell do these pluses and minuses mean!

The + and - just mean positive or negative for a certain enzyme or whatever you are talking about. So if something can grow without arginine and it is Arg+, that means it can produce arginine on its own and doesn't need arginine to be in the growth medium. The +/- is typically used to show a mutation of some sort. So if humans naturally produce enzyme "Enz" and you have a mutated Enz gene, then you are Enz-.

Originally Posted by MedPR

The + and - just mean positive or negative for a certain enzyme or whatever you are talking about. So if something can grow without arginine and it is Arg+, that means it can produce arginine on its own and doesn't need arginine to be in the growth medium. The +/- is typically used to show a mutation of some sort. So if humans naturally produce enzyme "Enz" and you have a mutated Enz gene, then you are Enz-.

Thanks a lot man! Makes sense

Also, I should clarify my original post. If the mutation in the Enz gene causes a problem in Enz production, then you are Enz-. If the mutation is silent or has no affect, you are still Enz+.