protein classification

meet the proteins

Hemoglobin is a compound in the class of compounds called proteins. Proteins are one of four classes of biochemi- cal compounds, which are compounds in living things. (The other three classes are carbohydrates, lipids, and nucleic acids.) Proteins contain carbon, hydrogen, oxygen, nitrogen, and sulfur. Protein molecules consist of one or more chains of small molecules called amino acids.

protein structure

Amino acids are the building blocks of proteins. There are 20 different amino acids. The structural formula of the simplest amino acid, called glycine, is shown in the Figure 1.1. Other amino acids have slightly different structures. A protein molecule is made from one or more long chains of amino acids, each linked to its neighbors by covalent bonds. If a protein has more than one chain, the chains are held together by weaker bonds, such as hydrogen bonds. The sequence of amino acids in chains and the number of chains in a protein determine the proteins shape. The shape of a protein, in turn, determines its function. Shapes may be very complex. Click image to the left or use the URL below. URL: Q: What do you think the ribbons in the colorful hemoglobin molecule pictured in the opening image represent? A: The ribbons represent chains of amino acids.

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protein functions

Proteins are the most numerous and diverse biochemical compounds, and they have many different functions. Some of their functions include: making up tissues as components of muscle. speeding up biochemical reactions as enzymes. regulating life processes as hormones. helping to defend against infections as antibodies. carrying materials around the body as transport proteins (see the example of hemoglobin in the Figure 1.2).

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instructional diagrams

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questions

proteins are the most numerous and diverse biochemical compounds.

-->  a. true

b. false

elements that make up proteins include

-->  a) nitrogen.

b) phosphorus.

c) hemoglobin.

d) two of the above

there are hundreds of different amino acids.

a. true

-->  b. false

what determines the shape of a protein?

a) amino acid sequence of each chain

b) folding of each amino acid chain

c) number of amino acid chains

-->  d) all of the above

examples of proteins by function include

a) hormones.

b) antibodies.

c) enzymes.

-->  d) all of the above

some proteins carry other materials in the blood.

-->  a. true

b. false

diagram questions

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