Video Transcript
Melvin Calvin investigated
photosynthesis in algae. He determined that, in the process,
a three-carbon compound was formed. What are the carbon atoms of this
compound used for in plant cells? (A) To help synthesize other key
elements such as oxygen, hydrogen, and calcium. (B) To be used as a reactant in
chemosynthesis. (C) To act as cell signaling
molecules. Or (D) to synthesize key biological
molecules such as glucose, starch, proteins, and fats.
Melvin Calvin was an American
biochemist who studied photosynthesis in the 1940s. It was his work on green algae that
led to the development of the Calvin cycle, the sequence of chemical reactions which
summarized the light-independent stage of photosynthesis that happens in all
photosynthetic organisms, including plants. One of the key compounds that’s
made during the carbon cycle is phosphoglyceraldehyde. Phosphoglyceraldehyde, or PGAL for
short, is a three-carbon compound as you can see from the diagram of its chemical
structure.
Once PGAL has been made, its carbon
atoms are used to synthesize other organic compounds, which are vital for the growth
and survival of plants. They can synthesize glucose, which
is primarily used for cellular respiration to release energy. They can produce starch, which is a
molecule used by plants to store energy. They can be used to synthesize
proteins, which act as structural components and catalyze chemical reactions. And finally, they can make fats,
which are stored in pollen grains and seeds.
We have therefore determined that
the correct answer to the question is (D). The carbon atoms of the
three-carbon compound that’s formed during photosynthesis are used to synthesize key
biological molecules such as glucose, starch, proteins, and fats.