Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site phri.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!timeinc!phri!lonetto From: lonetto@phri.UUCP (Michael Lonetto) Newsgroups: net.origins Subject: Re: Creation of Life Message-ID: <260@phri.UUCP> Date: Thu, 13-Jun-85 14:42:09 EDT Article-I.D.: phri.260 Posted: Thu Jun 13 14:42:09 1985 Date-Received: Sat, 15-Jun-85 06:08:41 EDT References: <1124@uwmacc.UUCP> <640@cadovax.UUCP> Organization: Public Health Research Inst. (NY, NY) Lines: 70 > >By the way, what is a "DNA protein"? > > I think that the subgroups of amino acids which are the building blocks of DNA are considered 'proteins', though I'm sure I could stand some more detailed > enlightenment on this subject. At work, my only ready reference is the > > Keith Doyle > # {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd Huh? Now wait a minute here. If we're going to talk about DNA and RNA and protein we're all going to have to speak the same language or the discussion degenerates to babble. The building blocks of DNA are deoxyribonucleotides. DNA means deoxyribonucleic acid. Each building block consists of a five carbon sugar molecule(ribose)which is ring shaped. This is attached at the first carbon to a purine or pyrimidine base and at the last carbon to a phosphate group. DNA is made up of two strands, each of which is made up of deoxyribonucleotides(see above) which are attached to each other by sugar-phosphate bonds. The identity of the base of each nucleotide is what gives the base its identity. The base identities are what is referred to as "DNA sequence". The possible bases are adenine, guanine, thymine and cytosine(A,G,C and T). Since an A on one strand always pairs with a T on the opposite (complementary) strand, and a G on one strand always pairs with a C on the complementary strand, the INFORMATION encoded in the DNA can be propagated: ie: each strand of DNA can serve as a template for the synthesis of a complementary strand the information in that DNA can be propagated as an organism grows (each cell gets a copy of all the information) and the organism's descendants each get a copy of the information(NO NITPICKING, I'M TRYING TO KEEP THIS SIMPLE). The information on some of the DNA can specify the structure of proteins. In order for this to happen an RNA (ribonucleic acid) copy of the DNA sequence must be made. This is very similar to new DNA synthesis, with the exception that only part of one strand of the DNA is copied. The information is still in essentially the same form as it was in the DNA: a linear sequence with a four letter alphabet. To turn this information into protein the 4 letter alphabet must be translated to the 20 letter alphabet of AMINO ACIDS that are the building blocks of protein. In addition the protein must fold into the proper 3 dimensional form required for "activity". Proteins DO things. They are enzymes (catalysts), hormones(messengers), recognition (binding) sites, structures within and around the cell, etc. The proper sequence of amino acids must be synthesized for each protein in a cell to function. The way the 4 letter code is translated to a 20 letter code is through "triplets": From a given start site on an RNA which the cell machinery recognizes three bases at a time (three letter words in a four letter alphabet) are read to specify one amino acid. Since there are 64 combinations of three it's easy to see how a four letter code can specify a sequence in 20 letter code. This is already too long and I have to go back to work, but much more basic information and PICTURES (which make things much clearer) are available in : BIOCHEMISTRY by Lehninger - Highly reccomended as the most self explanatory undergraduate biochemistry text - any library should have this one. or BIOCHEMISTRY by Lubert Stryer - I haven't read this one but it has excellent pictures of molecules and structures. -- Michael Lonetto PHRI NYC (allegra!phri!lonetto) "Some win, Some lose, Some refuse to play"