Why Do Different Foods Contain the Nutrients That They Do?

Or: what is the function in the organism?

 

 

 

MEAT

TUBERS

GRAINS

BEANS

LEAVES

FRUITS

STEMS

Carbohydrate

none

lots

lots

lots

little

some

little

Protein

lots

little

some

some

little

little

little

Fat

lots

little

little

little

little

little

little

 

 

 

 

 

 

 

 

This is exactly the kind of protein we have in our own bodies (muscle).

 

 

 

 

 

Examples:

Celery

Rhubarb

 

Over-winter storage organs need lots of starch to fuel growth in spring.  Little protein because plant can make its own from glucose + NH4 (from soil).

 

 

 

 

 

 

 

Seeds need lots of starch to fuel growth of seedling until it can develop leaves to feed itself.  Protein is also needed, because seedling canÕt get NH from soil until its roots are functional.

 

 

 

 

 

 

Leaves make glucose, but ship it elsewhere, so relatively little is left.

 

 

 

 

 

 

Fruits are a trade-off for plants.  They have as little stored energy as possible, and therefore have little protein and relatively little starch.  The starch they have is often converted to sweet fructose during ripening.

 

 

 

 

 

 

Stems are transport tubes that move glucose from leaves where it is made to other organs where it is either stored for future use (seeds, tubers) or where it is used immediately for growth.  Some is assembled into cell walls, but most is metabolized via glycolysis and mitochondria to build ATP.