A question about protein carrier......

[immunologic]

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This is in the first Kaplan video of Physiology, corresponding to page 1 of the Kaplan notes:
The roffessor say::
"If the dynamics for D & K glucose are 'same' under 'controlled conditions', you have to guess, that the tranportation of the glucose will be by simple diffusion only.But if the dynamics are not the same, you have to know that D-Glucose will be transported by a protein carrier."
My questions are,

[a] What is the meaning of DYNAMICS here?

And what is the meaning of 'controlled conditions'?

[c]And how did you guys know that D-Glucose will diffuse & not be transported by protien transporters when the dynamics are same?
[d]And how did you guys know that D-Glucose will be transported by protien transporters when the dynamics are NOT same?


Thanks

 

[bgreet]

Just taking a stab at this... not sure if I'm completely correct on this but here it goes (haven't used the kaplan videos, just basing off of the sentence you gave)

[a] i'm assuming rate of transport
equal concentrations
[c+d] if a channel protein were involved on one but not the other, facilitated transport would ensue increasing the permeability of the given solute over baseline simple diffusion; if both forms of glucose have a membrane channel or both do not (ie, have the same mechanisms of transport across the membrane), the rates would be similar; however being that d-glucose is the only biologically important form of glucose, you wouldn't expect a cell to contain transport proteins for l-glucose and therefore it would be unlikely that if both had the same diffusion rates they would both have specific channels

 

[immunologic]

Thanks a lot bgreet.