In this module:

Definition and Functional Groups

Carbohydrates are either organic compounds with the general chemical formula C_x(H₂O)_y, or other molecules derived from them. Some examples of carbohydrates are glyceraldehyde (C₃H₆O₃, x = 3, y = 3), glucose (the main sugar found in your blood and the energy source for your brain, C₆H₁₂O₆, x = 6, y = 6) and sucrose (table sugar, C₁₂H₂₂O₁₁, x = 12, y = 11).

How did carbohydrates get their name? Type your answer in the space given, then click on the check button to see the answer.

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Now compare your answer to the one below.

19^th century chemists thought carbohydrates were simple combinations of carbon (carbo-) and water (-hydrates). They soon discovered, however, that the primary functional groups in carbohydrates were not water but hydroxyl, aldehyde, and ketone groups instead. (Remember that R can refer to any organic group. In the ketone group, the prime after the R on the right simply means that that organic group can be different from the other one.)

From the following list of compounds, pick the one(s) that could be carbohydrates. Click on the Check box when you are done.

	Glycerol (C3H8O3)
	Ribose (C5H10O5)		Remember, the general formula for carbohydrates is Cx(H20)y.
	Galactose (C6H12O6)		Correct! But is there another?
	Ethanamine (C2H5NH2)		Correct! Ribose and galactose are both common carbohydrates.