Biology (Mader), 10th Edition

Chapter 3: The Chemistry of Organic Molecules

Protein and Muscle Production

What sets proteins apart from lipids and carbohydrates? Proteins are one of the three basic types of organic molecules that we use as food. The three types are carbohydrates, lipids, and proteins. All three types have a molecular skeleton of carbon and hydrogen atoms with a smaller number of oxygen atoms. Proteins are composed of amino acids. Each amino acid contains an amine group with a nitrogen atom. Nitrogen is required to synthesize proteins. Plants obtain nitrogen from the soil. Most plant tissue, with the exception of some seeds and fruits, has fairly small amounts of protein. Animal tissue has much higher amounts of protein.

View the animation below, then complete the quiz to test your knowledge of the concept.



1.

When a person eats more protein than their body needs the extra protein is
A)stored and used as protein when it is needed.
B)passed out of the body in feces.
C)converted to glucose or fat.
D)used to form extra large muscle.
2.

When protein is converted to glucose or fat, how is nitrogen eliminated from the body?
A)through the kidneys
B)through spitting or vomiting
C)through sweat
D)through feces
3.

If a 180 pound man eats an adequate diet, with about 2220 kcals, approximately what % of protein calories are used to build muscle?
A)7%
B)8%
C)15%
D)44%
4.

Increasing protein from 15% of calories to 30% of calories allows more protein to be used for
A)muscle.
B)water.
C)alcohol.
D)energy.
5.

Excess dietary protein and amino acids
A)build muscle.
B)do not build muscle.
C)cause weight loss.
D)make hair grow faster.
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