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How Proteins Are Made

For simplicity, we illustrate a protein made of 10 amino acids. Most proteins have more than 100

1 A special protein zips open a section of the DNA strands

Protein

2 Free RNA bases link up with the exposed DNA bases on one strand only, thus forming a strand of messenger RNA

Free RNA bases

3 The newly made messenger RNA peels off and moves away to the ribosomes

4 A transfer RNA picks up an amino acid and brings it to the ribosome

Transfer RNA

Ribosome

5 As the ribosome sweeps across the messenger RNA, a chain of amino acids is linked together

Amino acids

6 As it is being formed, the protein chain begins to fold into the shape needed to function properly. Then the chain is released by the ribosome

Transfer RNA has two important ends:

One recognizes the messenger RNA code

The other carries the correct amino acid

Transfer RNA

RNA bases use U rather than T, so U pairs with A

A U Uracil

U A Adenine

What Is Behind the Mystery of Life?

THE DNA molecule does amazing things. DNA fulfills both the roles that your cells require of genetic material. First, the DNA is accurately duplicated so that information can be passed on from cell to cell. Second, the DNA sequence tells the cell what proteins to make, thereby determining what the cell will become and what function it will serve. However, DNA does not carry out these processes on its own. Many specialized proteins are involved.

DNA alone cannot create life. It contains all the instructions needed to make all the proteins a living cell needs, including the very ones that copy DNA for the next cell generation and the ones that help DNA to make new proteins. Still, the incredible amount of information stored in the DNA genes is useless without RNA and the specialized proteins, which include ribosomes, needed to “read” and use that information.

Neither can proteins alone produce life. An isolated protein cannot generate the gene that has the code for making more of that same type of protein.

So, what has unraveling the mystery of life shown? Modern genetics and molecular biology have provided ample evidence of the highly complex and interdependent relationships between DNA, RNA, and protein. These findings imply that life depends on having all these elements simultaneously. Thus, life could never have come about spontaneously by chance.