confusing electrophoresis question

[ilovemedi]

I don't get this question (from TBR): how do I approach this? I'm confused as to how to determine if it's a tetramer or not.. I know middle lane = mixture.

Answer: highlighted - C

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[brothersport]

Wouldn't the five distinct bands in Lane 2 indicate a pentamer?

 

[deleted103644]

Wouldn't the five distinct bands in Lane 2 indicate a pentamer?

No.

You have five different types of tetramers with two types of components.

AAAA
AAAB
AABB
ABBB
BBBB

The bands in the other lanes are AAAA and BBBB.

 

[deleted103644]

-------- bbbb bbbb
-------- abbb --------
-------- aabb --------
-------- aaab --------
aaaa aaaa --------

 

[ilovemedi]

@johnny: yup! answer is C. how did you even know to start with AAAA? and not AAA for example?

 

[deleted103644]

@johnny: yup! answer is C. how did you even know to start with AAAA? and not AAA for example?

Unless they included many more bands, it was only going to be a single type of quaternary structure (ie all tetramers).