Gene Translation Complexity of Living Things

"Enter transfer RNA: Theory and experiment meet to find the key adaptor for gene translation." by Mahlon Hoagland (Nature v. 431, 16 Sept. '04, p. 249) is an "essay: turning points" article about the discovery of transfer RNA, showing a historical case of the discovery of part of the complexity of living things.

"By the 1950s, scientists generally assumed that converting genetic information into the substance of life was a matter of translation. A DNA sequence, made from a combination of four kinds of nucleotides, was translated into a protein sequence, which was made from a combination of twenty kinds of amino acids. But how did this translation occur, and what machinery was involved?"

When Hoagland got involved in the search for answers, they already knew that two components were required: ribosomes and ... well, something soluble but not specifically identified. Oh yes, and "In addition, the nucleotide ATP was found to supply the energy essential for the process."

Hoagland found out that there were enzymes in the soluble part that slapped part of ATP molecules onto amino acids, giving them a packet of chemical energy which they could use (needed) to join up and form proteins.

Later on, it was discovered that when all the components were together, small bits of RNA floating in the soluble fraction also became attached to the amino acids. These bits of RNA had been "presumed to be 'junk' -- fragments of the larger RNA from the ribosomes," maybe just bits that had broken off during processing of the cell for investigation.

As it turned out, these odd bits were just what cells need to complete the "machinery" of translation. "As there is no chemical similarity or complementarity between amino acids and nucleotides, and thus no means by which they could directly interact, Crick suggested that amino acids might be first attached to short single strands of RNA nucleotides."

The researchers were unaware of this prediction, and were quite surprised when they found out about it.

Until Next Time,

David Bump
Philippians 3: 13 Brethren, I
count not myself to have
apprehended: but [this] one thing
[I do], forgetting those things
which are behind, and reaching
forth unto those things which are
before, 14 I press toward the
mark for the prize of the high
calling of God in Christ Jesus.

http://home.att.net/~david.bump