Question

The diagram below illustrates two different protein molecules found in organisms. Which of the following statements is not correct?

The proteins have different functions
The proteins are both composed of amino acids
The sequence of amino acids in both proteins are the same
The shapes of these proteins determine their functions.

Answer 1

Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective; they may serve in transport, storage, or membranes; or they may be toxins or enzymes. Each cell in a living system may contain thousands of different proteins, each with a unique function. Their structures, like their functions, vary greatly. They are all, however, polymers of alpha amino acids, arranged in a linear sequence and connected together by covalent bonds.

Alpha Amino Acid Structure

The major building block of proteins are called alpha (α) amino acids. As their name implies they contain a carboxylic acid functional group and an amine functional group. The alpha designation is used to indicate that these two functional groups are separated from one another by one carbon group. In addition to the amine and the carboxylic acid, the alpha carbon is also attached to a hydrogen and one additional group that can vary in size and length. In the diagram below, this group is designated as an R-group. Within living organisms there are 20 amino acids used as protein building blocks. They differ from one another only at the R-group position. The basic structure of an amino acid is shown below:

Figure 2.1 General Structure of an Alpha Amino Acid

There are a total of 20 alpha amino acids that are commonly incorporated into protein structures (Figure 2.x). The different R-groups have different characteristics based on the nature of atoms incorporated into the functional groups. There are R-groups that predominantly contain carbon and hydrogen and are very nonpolar or hydrophobic. Others contain polar uncharged functional groups such as alcohols, amides, and thiols. A few amino acids are basic (containing amine functional groups) or acidic (containing carboxylic acid functional groups). These amino acids are capable of forming full charges and can have ionic interactions. Each amino acid can be abbreviated using a three letter and a one letter code.

Step-by-step explanation