(1) TNA (threose nucleic acid) is being examined by astrobiologists as a possible predecessor to DNA due to its ability to base pair with RNA and DNA. (2) TNA has a simpler molecular structure than RNA and DNA, using the four carbon sugar threose instead of the five carbon ribose. (3) Studies have shown that TNA can form stable double helices and pair with RNA and DNA strands, suggesting it could have served as a genetic system before the evolution of RNA and DNA.
Toward the expansion of the genetic alphabet of DNA, several artificial third base pairs (unnatural base pairs) have been created. Organisms are defined by the information encoded in their genomes, and since the origin of life this information has been encoded using a two-base-pair genetic alphabet (A–T and G–C). In vitro, the alphabet have been expanded to include several unnatural base pairs (UBPs). A class of UBPs formed between nucleotides bearing hydrophobic nucleobases, exemplified by the pair formed between d5SICS and dNaM (d5SICS–dNaM) was developed, which is efficiently PCR-amplified and transcribed in vitro, and whose unique mechanism of replication has been characterized. However, expansion of an organism’s genetic alphabet presents new and unprecedented challenges: the unnatural nucleoside triphosphates must be available inside the cell; endogenous polymerases must be able to use the unnatural triphosphates to faithfully replicate DNA containing the UBP within the complex cellular milieu; and finally, the UBP must be stable in the presence of pathways that maintain the integrity of DNA. In a major breakthrough, it was reported that an exogenously expressed algal nucleotide triphosphate transporter efficiently imports the triphosphates of both d5SICS and dNaM (d5SICSTP and dNaMTP) into Escherichia coli, and that the endogenous replication machinery uses them to accurately replicate a plasmid containing d5SICS–dNaM was already reported. Neither the presence of the unnatural triphosphates nor the replication of the UBP introduces a notable growth burden. Thus, the resulting bacterium is the first semi-synthetic organism to propagate stably an expanded genetic alphabet. The unnatural base pair systems now have high potential to open the door to next generation biotechnology.
GENETIC MATERIAL refers to the material of which genes are made up of. It includes both DNA and RNA. Though in most of the organism DNA is playing this role, but in certain viruses RNA is storing all the genetic information of the individual. Here we are discussing about the discovery and property of these genetic material.
A brief account of interesting history of nucleic acids...including 'the most beautiful experiment on biology'. Most of the presentation is derived from the book 'man made life' by Jeremy Cherfas.
Toward the expansion of the genetic alphabet of DNA, several artificial third base pairs (unnatural base pairs) have been created. Organisms are defined by the information encoded in their genomes, and since the origin of life this information has been encoded using a two-base-pair genetic alphabet (A–T and G–C). In vitro, the alphabet have been expanded to include several unnatural base pairs (UBPs). A class of UBPs formed between nucleotides bearing hydrophobic nucleobases, exemplified by the pair formed between d5SICS and dNaM (d5SICS–dNaM) was developed, which is efficiently PCR-amplified and transcribed in vitro, and whose unique mechanism of replication has been characterized. However, expansion of an organism’s genetic alphabet presents new and unprecedented challenges: the unnatural nucleoside triphosphates must be available inside the cell; endogenous polymerases must be able to use the unnatural triphosphates to faithfully replicate DNA containing the UBP within the complex cellular milieu; and finally, the UBP must be stable in the presence of pathways that maintain the integrity of DNA. In a major breakthrough, it was reported that an exogenously expressed algal nucleotide triphosphate transporter efficiently imports the triphosphates of both d5SICS and dNaM (d5SICSTP and dNaMTP) into Escherichia coli, and that the endogenous replication machinery uses them to accurately replicate a plasmid containing d5SICS–dNaM was already reported. Neither the presence of the unnatural triphosphates nor the replication of the UBP introduces a notable growth burden. Thus, the resulting bacterium is the first semi-synthetic organism to propagate stably an expanded genetic alphabet. The unnatural base pair systems now have high potential to open the door to next generation biotechnology.
GENETIC MATERIAL refers to the material of which genes are made up of. It includes both DNA and RNA. Though in most of the organism DNA is playing this role, but in certain viruses RNA is storing all the genetic information of the individual. Here we are discussing about the discovery and property of these genetic material.
A brief account of interesting history of nucleic acids...including 'the most beautiful experiment on biology'. Most of the presentation is derived from the book 'man made life' by Jeremy Cherfas.
Introduction to Genetic Material, Physical and Chemical properties of the same and various types of coiling mechanisms as well as information about chromosomal and extra-chromosomal DNA.
Nucleic acid and its chemistry, dna as genetic materialdeepa sundari
The nucleic acids are vital biopolymers found in all living organisms, where they function to encode, transfer, and express genes. The nucleic acids are of two types, namely deoxyribonucleic acid (DNA) and ribonucleic acid(RNA).
EVER WONDERED WHY DNA IS GENETIC MATERIAL INSTEAD OF RNA OR PROTEIN?
Biochemical Evidence For dna As Genetic MaterialShylesh M
Biochemical Evidence For dna As Genetic Material
What is genetic material The genetic information in all cell is stored in DNA ,Discovery of Transformation in Bacteria , The transforming principle is DNA , HERSHEY & CHASE (1952) EXPERIMENT WITH T2 BACTERIOPHAGE, Summary of Hershey & Chase (1952 ) experiment
DNA caries genetic information of organisms. This presentation covers the discovery of DNA as genetic material, structure of DNA, Nucleotides and nucleosides. Watson and crick DNA model.
DNA - The building blocks of all life - lecture notes from a presentation by Jill Pullan to Mansfield U3A Science and Technical group.
http://www.mansfield-u3a.org.uk/.
Introduction to Genetic Material, Physical and Chemical properties of the same and various types of coiling mechanisms as well as information about chromosomal and extra-chromosomal DNA.
Nucleic acid and its chemistry, dna as genetic materialdeepa sundari
The nucleic acids are vital biopolymers found in all living organisms, where they function to encode, transfer, and express genes. The nucleic acids are of two types, namely deoxyribonucleic acid (DNA) and ribonucleic acid(RNA).
EVER WONDERED WHY DNA IS GENETIC MATERIAL INSTEAD OF RNA OR PROTEIN?
Biochemical Evidence For dna As Genetic MaterialShylesh M
Biochemical Evidence For dna As Genetic Material
What is genetic material The genetic information in all cell is stored in DNA ,Discovery of Transformation in Bacteria , The transforming principle is DNA , HERSHEY & CHASE (1952) EXPERIMENT WITH T2 BACTERIOPHAGE, Summary of Hershey & Chase (1952 ) experiment
DNA caries genetic information of organisms. This presentation covers the discovery of DNA as genetic material, structure of DNA, Nucleotides and nucleosides. Watson and crick DNA model.
DNA - The building blocks of all life - lecture notes from a presentation by Jill Pullan to Mansfield U3A Science and Technical group.
http://www.mansfield-u3a.org.uk/.
DNA is a double helical structure that transfers the genetic information from one generation to another. it consists of two strands with the four nucleotide basis .The four nucleotides contains adenine, cytosine, guanine, thymine .These four nuclic basis are such arranged and coiled with the help of hydrogen bonds and forms the helical structure of DNA. In RNA the thymine is replaced with uracil. Here you will learn the replication ,transcription and translation process in DNA.
1. TNA WORLD
. . . . . . . . Is TNA is the proginator of DNA?
By:
Desh Bandhu Gangwar
M.Tech Biotech (2 year)
10/pbt/006
DNA is building block for life on earth. But it is highly complex molecule and
could not be arranged itself spontaneously. What did it develop from?
Astrobiologist examine possible ancestor of DNA: nucleic acid called TNA.
(3’-2’)-alfa-L-Threose nucleic acid (TNA) is an unnatural polymer that posses
the rare ability to base pair with RNA, DNA and itself. This feature coupled with
its chemical simplicity, makes TNA of interest as a possible proginator of DNA
during the early history of life.
Scientist have put forth the theory that RNA was the predecessor of DNA and
evolved into that more complex molecule. But while RNA is slightly simpler
then DNA, it too is very complex. So what is the ancestor of RNA? One recent
report suggested that it may have been yet another nucleic acid called (3’-2’)-
alfa-L-Threose nucleic acid also known as TNA.
Dr. Albert Eschenmoser and his colleagues at the scripps research institute in
La Jolla, California, and the federal institute of technology in zurich,
Switzerland, chemically synthesized TNA in a number of steps.
They found that complementary TNA strands can form stable double helix. The
TNA strand can also pair up with complementary strand of RNA and DNA. This
ability is though to be one of the requirement of any system that would be
considered a possible ancestor of RNA. A second requirement is that it should
be a simpler molecule than RNA.
The backbone of DNA and RNA composed of sugar molecule-ribose for RNA
and deoxyribose for DNA- that contain five carbon atom.
In TNA that backbone composed of sugar molecules threose that contain only
four carbon atom. under nonbiological conditions, threose form easily than
ribose.
2. But it is not only the number of the carbon atoms that threose an intrisically
simpler molecule than ribose. it is also the fact that, unlike ribose, the simplest
formation of threose requires only a single type of starting material.
TNA does not occur naturally today. Scientists have to create it in the lab in
order to study it. Since we can’t go back in time to witness the evolution of
nucleic acid, we will never to prove whether natural TNA made an appearance
on earth.
But scientist can examine the basic property of TNA and determine whether
they could have formed in a prebiotic earth environment. The reason for
synthesizing and studying it to screen the structural nighborhood of RNA for
potential nucleic acid alternative that could also have fulfilled the function of
genetic system. The origin of DNA are confronted with a paradox. DNA needs
certain proteins to replicate. But in order to make the correct proteins for this
function, modern cells need to have DNA. Since DNA and the proteins are
dependent on each other. It is hard to see how either of them could have
come first. One answer to this riddle is the RNA world theory, which suggested
that both DNA and protein could descendents of RNA. But where did RNA
come from? To date no one has been able to form RNA under in the laboratory
under condition that mimic those believed to have existed on primitive earth.
Some scientist also question whether nucleic acid with a backbone of ribose, or
any other sugar molecule, would be stable enough to survive the harsh
condition of early earth.
So it is generally agreed that RNA must have evolved from an earlier form,
while TNA is a good candidate other polymer that exhibit self replication and
base pairing could have evolved into RNA. TNA is the best bet so far.