Secondary Active transport in MCAT terms

[ahs4n]

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If an Mcat question ever asks if Secondary active transport requires energy, would the answer be yes it does because it needs the coupling or no because it does not directly use ATP? In all likely hood, I know a question would never be so simple..but I feel like something like this is sort of misleading.

 

[engineeredout]

I think you're pretty safe with:

For the MCAT: (any) Active transport = ATP.

Facilitated Diffusion/Osmosis = No ATP.

 

[FuturaDocta]

Definitely go with active transport, since that is what all my teachers categorize secondary as. I think the reason it may be confusing has to do with the macromolecules and protons coming back in the cell through a passive process, when it was sparked by the electrogenic pump to begin with. Therefore, it is not passive.

As said before, if there is any atp in the reaction, then it would be categorized as active. This is something that should be applied to all your questions.

Hope this is helpful.

 

[johndoe3344]

That is not exactly correct. Active transport is whenever you pump something against a concentration gradient, REGARDLESS of whether it uses ATP.

Here's a question from EK: In some specialized cells, glucose is transported against its concentration gradient via an integral protein using the energy of the sodium ion electrochemical gradient. If no ATP is used for this transport, it is most likely:

The answer is active transport. Not facilitated.

 

[FuturaDocta]

That is not exactly correct. Active transport is whenever you pump something against a concentration gradient, REGARDLESS of whether it uses ATP.

Here's a question from EK: In some specialized cells, glucose is transported against its concentration gradient via an integral protein using the energy of the sodium ion electrochemical gradient. If no ATP is used for this transport, it is most likely:

The answer is active transport. Not facilitated.

A-HA! I stand corrected. I forgot about that one exception (if you don't mind, let me know if there is another).

Here is a video to help clarify for others:
http://highered.mcgraw-hill.com/cla...56208&alaid=ala_855073&showSelfStudyTree=true

Take a look at the other videos on the site. I find it very helpful, since I do well with visuals. Hope this helps!