What is the primary energy source for cells?

[HAiKUGiRL]

A) Starch
B) Cellulose
C) Glucose
D) Sunlight
E) ATP

I'm debating between glucose and sunlight..

I know sunlight provides the energy source for food chains, etc. but glucose also provides energy to the cell after glycolysis and stuff.

Anyone?

[mith]

Can you survive on sunlight?

[HAiKUGiRL]

Never any definitive answers are there

no you can't survive on it

[mith]

It isn't? I thought it's pretty cut and dry.

[Darby]

It all comes down to how you define "primary."

If it's the source that actually is used when cell processes need energy, it's one thing.

If it's the material that cells take in and convert, it's another thing.

If it's the first step in the line, it's something else.

Those all could be defined as "primary sources."

Hey, that eliminates 3 possibilities...

[HAiKUGiRL]

Apparently my teacher said it was ATP .. ahh shucks.

[Cat]

Your teacher is wrong.

A) Starch - Primary energy storage (in plants)
B) Cellulose - Structural, can be used for energy only by some fungi and maybe few bacteria
C) Glucose - Primary energy source
D) Sunlight - Required for photosynthesis light RXN.
E) ATP - Primary energy currency

[mith]

Poor question and/or answer. ATP is an intermediate for energy use but it is by no means a "source."

[MichaelXY]

I found this on a website, and they worded it as follows:

Mitochondria: Mitochondria provide the energy a cell needs to move, divide, produce secretory products, contract - in short, they are the power centers of the cell. They are about the size of bacteria but may have different shapes depending on the cell type. Mitochondria are membrane-bound organelles, and like the nucleus have a double membrane. The outer membrane is fairly smooth. But the inner membrane is highly convoluted, forming folds (cristae) as seen in the cross-section, above. The cristae greatly increase the inner membrane's surface area. It is on these cristae that food (sugar) is combined with oxygen to produce ATP - the primary energy source for the cell.

[Cat]

ATP has been called many things:
primary energy source
energy storage
energy currency

I can find books and webs for each one, so, I agree with Mith that question is unfair.

only energy currency is the one that makes most sense.
Source, in my understanding, is where energy is coming from, in this case - glucose is the source and ATP is product.

[MichaelXY]

Ok, let's suppose that you were asked the question; what is the primary source of energy for an automobile?
Would you answer gasoline, or crude oil?

[Cat]

Crude oil has nothing to do with the car. I am not calling sucrose a primary energy source either.

O.K. Let’s try your analogy:

Glucose to ATP to energy
Benzene to intermediate to energy

Would you call benzene a source or one of the intermediates (say phenol) as source? To me ‘source’ is whatever you add to the system to get energy.

Maybe between us we could give a consensus on what ATP should be called – as far as I understand there isn’t one yet.