Question

Discuss what is meant bg the following paradigm of all life: DNA >RNA>PROTEIN

Answer 1

We know, a single life start from protein. In a leaving orgamism protein is present in everywhere. We also know that, the cell which the stractural unit of an organism, it's stracture is made by protein known phospholipid.

Now we need to know what is DNA , RNA and PROTEIN

DNA --  DNA is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, it is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

RNA - Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and DNA are nucleic acids, and, along with lipids, proteins and carbohydrates, constitute the four major macromolecules essential for all known forms of life.

It is principally involved in the synthesis of proteins, carrying the messenger instructions from DNA, which itself contains the genetic instructions required for the development and maintenance of life. In some viruses, RNA, rather than DNA, carries genetic information.

PROTEIN -  Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells, and organisms, and transporting molecules from one location to another.

The central dogma of molecular biology is an explanation of the flow of genetic information within a biological system. It is often stated as "DNA makes RNA, and RNA makes protein.

"The Central Dogma. This states that once "information" has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible. Information means here the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein".

— Francis Crick, 1958

This is the simplistic DNA → RNA → protein pathway

The dogma is a framework for understanding the transfer of sequence information between information-carrying biopolymers, in the most common or general case, in living organisms.

We will discuss how a protein is synthesized from a single DNA(deoxyribonucleic acid) molecule.

Replication in molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritance. The cell possesses the distinctive property of division, which makes replication of DNA essential.

Transcription is the first of several steps of DNA based gene expression in which a particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript.

Translation in molecular biology and genetics, translation is the process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire process is called gene expression.

In translation, messenger RNA (mRNA) is decoded in the ribosome decoding center to produce a specific amino acid chain, or polypeptide. The polypeptide later folds into an active protein and performs its functions in the cell. The ribosome facilitates decoding by inducing the binding of complementary tRNA anticodon sequences to mRNA codons. The tRNAs carry specific amino acids that are chained together into a polypeptide as the mRNA passes through and is read by the ribosome.

DNA, RNA, and protein

The specific carrier of the genetic information in all organisms is the nucleic acid known as DNA, short for deoxyribonucleic acid. DNA is a double helix, two molecular coils wrapped around each other and chemically bound one to another by bonds connecting adjacent bases. Each long ladderlike DNA helix has a backbone that consists of a sequence of alternating sugars and phosphates. Attached to each sugar is a “base” consisting of the nitrogen-containing compound adenine, guanine, ctyosine, or thymine. Each sugar-phosphate-base “rung” is called a nucleotide. A very significant one-to-one pairing between bases occurs that ensures the connection of adjacent helices. Once the sequence of bases along one helix (half the ladder) has been specified, the sequence along the other half is also specified. The specificity of base pairing plays a key role in the replication of the DNA molecule. Each helix makes an identical copy of the other from molecular building blocks in the cell. These nucleic acid replication events are mediated by enzymes called DNA polymerases. With the aid of enzymes, DNA can be produced in the laboratory.

DNA in the cell nucleus carries a genetic code, which consists of sequences of adenine (A), thymine (T), guanine (G), and cytosine (C) . RNA, which contains uracil (U) instead of thymine, carries the code to protein-making sites in the cell. To make RNA, DNA pairs its bases with those of the “free” nucleotides (Figure 2). Messenger RNA (mRNA) then travels to the ribosomes in the cell cytoplasm, where protein synthesis occurs (Figure 3). The base triplets of transfer RNA (tRNA) pair with those of mRNA and at the same time deposit their amino acids on the growing protein chain. Finally, the synthesized protein is released to perform its task in the cell or elsewhere in the body.

The cell, whether bacterial or nucleated, is the minimal unit of life. Many of the fundamental properties of cells are a function of their nucleic acids, their proteins, and the interactions among these molecules bounded by active membranes. Within the nuclear regions of cells is a mélange of twisted and interwoven fine threads, the chromosomes. Chromosomes by weight are composed of 50–60 percent protein and 40–50 percent DNA. During cell division, in all cells but those of bacteria (and some ancestral protists), the chromosomes display an elegantly choreographed movement, separating so that each offspring of the original cell receives an equal complement of chromosomal material. This pattern of segregation corresponds in all details to the theoretically predicted pattern of segregation of the genetic material implied by the fundamental genetic laws (see heredity). The chromosome combination of the DNA and the proteins (histone or protamine) is called nucleoprotein. The DNA stripped of its protein is known to carry genetic information and to determine details of proteins produced in the cytoplasm of cells; the proteins in nucleoprotein regulate the shape, behaviour, and activities of the chromosomes themselves.

The other major nucleic acid is ribonucleic acid (RNA). Its five-carbon sugar is slightly different from that of DNA. Thymine, one of the four bases that make up DNA, is replaced in RNA by the base uracil. RNA appears in a single-stranded form rather than a double. Proteins (including all enzymes), DNA, and RNA have a curiously interconnected relation that appears ubiquitous in all organisms on Earth today. RNA, which can replicate itself as well as code for protein, may be older than DNA in the history of life.

Chemistry in common:

The genetic code was first broken in the 1960s. Three consecutive nucleotides (base-sugar-phosphate rungs) are the code for one amino acid of a protein molecule. By controlling the synthesis of enzymes, DNA controls the functioning of the cell. Of the four different bases taken three at a time, there are 43, or 64, possible combinations. The meaning of each of these combinations, or codons, is known. Most of them represent one of the 20 particular amino acids found in protein. A few of them represent punctuation marks—for example, instructions to start or stop protein synthesis. Some of the code is called degenerate. This term refers to the fact that more than one nucleotide triplet may specify a given amino acid. This nucleic acid–protein interaction underlies living processes in all organisms on Earth today. Not only are these processes the same in all cells of all organisms, but even the particular “dictionary” that is used for the transcription of DNA information into protein information is essentially the same. Moreover, this code has various chemical advantages over other conceivable codes. The complexity, ubiquity, and advantages argue that the present interactions among proteins and nucleic acids are themselves the product of a long evolutionary history. They must interact as a single reproductive, autopoietic system that has not failed since its origin. The complexity reflects time during which natural selection could accrue variations; the ubiquity reflects a reproductive diaspora from a common genetic source; and the advantages, such as the limited number of codons, may reflect an elegance born of use. DNA’s “staircase” structure allows for easy increases in length. At the time of the origin of life, this complex replication and transcription apparatus could not have been in operation. A fundamental problem in the origin of life is the question of the origin and early evolution of the genetic code.

Many other commonalities exist among organisms on Earth. Only one class of molecules stores energy for biological processes until the cell has use for it; these molecules are all nucleotide phosphates. The most common example is adenosine triphosphate (ATP). For the very different function of energy storage, a molecule identical to one of the building blocks of the nucleic acids (both DNA and RNA) is employed. Metabolically ubiquitous molecules—flavin adenine dinucleotide (FAD) and coenzyme A—include subunits similar to the nucleotide phosphates. Nitrogen-rich ring compounds, called porphyrins, represent another category of molecules; they are smaller than proteins and nucleic acids and common in cells. Porphyrins are the chemical bases of the heme in hemoglobin, which carries oxygen molecules through the bloodstream of animals and the nodules of leguminous plants. Chlorophyll, the fundamental molecule mediating light absorption during photosynthesis in plants and bacteria, is also a porphyrin. In all organisms on Earth, many biological molecules have the same “handedness” (these molecules can have both “left-” and “right-handed” forms that are mirror images of each other; see below The earliest living systems). Of the billions of possible organic compounds, fewer than 1,500 are employed by contemporary life on Earth, and these are constructed from fewer than 50 simple molecular building blocks.Besides chemistry, cellular life has certain supramolecular structures in common. Organisms as diverse as single-celled paramecia and multicellular pandas (in their sperm tails), for example, possess little whiplike appendages called cilia (or flagella, a term that is also used for completely unrelated bacterial structures; the correct generic term is undulipodia). These “moving cell hairs” are used to propel the cells through liquid. The cross-sectional structure of undulipodia shows nine pairs of peripheral tubes and one pair of internal tubes made of proteins called microtubules. These tubules are made of the same protein as that in the mitotic spindle, the structure to which chromosomes are attached in cell division. There is no immediately obvious selective advantage of the 9:1 ratio. Rather, these commonalities indicate that a few functional patterns based on common chemistry are used over and over again by the living cell. The underlying relations, particularly where no obvious selective advantage exists, show all organisms on Earth are related and descended from a very few common cellular ancestors—or perhaps one.

DNA stores the genetic information, where as RNA uses the information to help the cell produces the protein.Genes are DNA sequences instruct cells to produce particular proteins, which in turn determine traits. Chromosomes are strings of genes. Mutations are changes in gene's DNA sequence.DNA or other wise called deoxyribonucleic acid is the building block of the life. It contains the information the cell requires to synthesize protein and to replicate itself, to be short it is the storage repository for the information that is required for any cell to function. Watson-Crick has discovered the current-structure of DNA in 1953.The famous double-helix structure of DNA has its own significance. There are basically four nucleotide bases, which make up the DNA. Adenine (A), Guanine (G), Thymine (T) and Cytosine(C). A DNA sequence looks some thing like this "ATTGCTGAAGGTGCGG". DNA is measured according to the number of base pairs it consists of, usually in kBp or mBp(Kilo/Mega base pairs). Each base has its complementary base, which means in the double helical structure of DNA, A will have T as its complimentary and similarly G will have C. nbsp; DNA molecules are incredibly long. If all the DNA bases of the human genome were typed as A, C, T and G, the 3 billion letters would fill 4,000 books of 500 pages each! The DNA is broken down into bits and is tightly wound into coils, which are called chromosomes; human beings have 23 pairs of chromosomes. These chromosomes are further broken down into smaller pieces of code called Genes. The 23 pairs of chromosomes consist of about 70,000 genes and every gene has its own function. As I have mentioned earlier, DNA is made up of four nucleotide bases, finding out the arrangement of the bases is called DNA sequencing, there are various methods for sequencing a DNA, it is usually carried out by a machine or by running the DNA sample over a gel otherwise called gel electrophoresis. A typical sequence would look like this "ATTTGCTGACCTG".

Determining the gene's functionality and position of the gene in the chromosome is called gene mapping. Recent developments show that scientists are mapping every gene in the human body. They named their project Human Genome Project (HGP), which involves careful study of all the 70,000 genes in human body. Whew! That's some thing unimaginable. When there is a change in the genetic code it is called mutation.

The significance of a DNA is very high. The gene's sequence is like language that instructs cell to manufacture a particular protein. An intermediate language, encoded in the sequence of Ribonucleic Acid (RNA), translates a gene's message into a protein's amino acid sequence. It is the protein that determines the trait. This is called central dogma of life.

RNA is somewhat similar to DNA; they both are nucleic acids of nitrogen-containing bases joined by sugar-phosphate backbone. How ever structural and functional differences distinguish RNA from DNA. Structurally, RNA is a single-stranded where as DNA is double stranded. DNA has Thymine, where as RNA has Uracil. RNA nucleotides include sugar ribose, rather than the Deoxyribose that is part of DNA. Functionally, DNA maintains the protein-encoding information, whereas RNA uses the information to enable the cell to synthesize the particular protein.

From the above discussion we can concluded that, The genetic information is transfer DNA to RNA to PROTEIN. So the following process is paradigm of all life.