the basic components of dna are

Hello dear friends, solsarin in this article is talking about “the basic components of dna are”.

we are happy to have you on our website.

What does DNA do?

DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies.

Each DNA sequence that contains instructions to make a protein is known as a gene. The size of a gene may vary greatly, ranging from about 1,000 bases to 1 million bases in humans. Genes only make up about 1 percent of the DNA sequence. DNA sequences outside this 1 percent are involved in regulating when, how and how much of a protein is made.

How are DNA sequences used to make proteins?

DNA’s instructions are used to make proteins in a two-step process. First, enzymes read the information in a DNA molecule and transcribe it into an intermediary molecule called messenger ribonucleic acid, or mRNA.

Next, the information contained in the mRNA molecule is translated into the “language” of amino acids, which are the building blocks of proteins. This language tells the cell’s protein-making machinery the precise order in which to link the amino acids to produce a specific protein. This is a major task because there are 20 types of amino acids, which can be placed in many different orders to form a wide variety of proteins.

Who discovered DNA?

The Swiss biochemist Frederich Miescher first observed DNA in the late 1800s. But nearly a century passed from that discovery until researchers unraveled the structure of the DNA molecule and realized its central importance to biology.

the basic components of dna are

For many years, scientists debated which molecule carried life’s biological instructions. Most thought that DNA was too simple a molecule to play such a critical role. Instead, they argued that proteins were more likely to carry out this vital function because of their greater complexity and wider variety of forms.

The importance of DNA became clear in 1953 thanks to the work of James Watson*, Francis Crick, Maurice Wilkins and Rosalind Franklin. By studying X-ray diffraction patterns and building models, the scientists figured out the double helix structure of DNA – a structure that enables it to carry biological information from one generation to the next.

* James Watson was the first NHGRI Director and appears here as part of our history collection. Despite his scientific achievements, Dr. Watson’s career was also punctuated by a number of offensive and scientifically erroneous comments about his beliefs on race, nationalities, homosexuality, gender, and other societal topics. Dr. Watson’s opinions on these topics are unsupported by science and are counter to the mission and values of NHGRI.

What is the DNA double helix?

Scientist use the term “double helix” to describe DNA’s winding, two-stranded chemical structure. This shape – which looks much like a twisted ladder – gives DNA the power to pass along biological instructions with great precision.

To understand DNA’s double helix from a chemical standpoint, picture the sides of the ladder as strands of alternating sugar and phosphate groups – strands that run in opposite directions. Each “rung” of the ladder is made up of two nitrogen bases, paired together by hydrogen bonds. Because of the highly specific nature of this type of chemical pairing, base A always pairs with base T, and likewise C with G. So, if you know the sequence of the bases on one strand of a DNA double helix, it is a simple matter to figure out the sequence of bases on the other strand.

DNA’s unique structure enables the molecule to copy itself during cell division. When a cell prepares to divide, the DNA helix splits down the middle and becomes two single strands. These single strands serve as templates for building two new, double-stranded DNA molecules – each a replica of the original DNA molecule. In this process, an A base is added wherever there is a T, a C where there is a G, and so on until all of the bases once again have partners.

DNA

The Components of DNA, The Structure of Double-Stranded DNA, Alternative DNA Conformations

DNA (deoxyribonucleic acid) was discovered in the late 1800s, but its role as the material of heredity was not elucidated for fifty years after that. It occupies a central and critical role in the cell as the genetic information in which all the information required to duplicate and maintain the organism. All information necessary to maintain and propagate life is contained within a linear array of four simple bases: adenine, guanine, thymine, and cytosine.

Bases and Base Pairs.

The four bases found in DNA are shown in Figures 1 and 2. The purines and pyrimidines are the informational molecules of the genetic blueprint for the cell. The two sides of the helix are held together by hydrogen bonds between base pairs. Hydrogen bonds are weak attractions between a hydrogen atom on one side and an oxygen or nitrogen atom on the other. Hydrogen atoms of amino groups serve as the hydrogen bond donor while the carbonyl oxygens and ring nitrogens serve as hydrogen bond acceptors. The specific location of hydrogen bond donor and acceptor groups gives the bases their specificity for hydrogen bonding in unique pairs. Thymine (T) pairs with adenine (A) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds (Figure 2). T does not normally pair with G, nor does C normally pair with A.

the basic components of dna are

Deoxyribose Sugar.

In DNA the bases are connected to a β-D-2-deoxyribose sugar with a hydrogen atom at the 2′ (“two prime”) position. The sugar is a very dynamic part of the DNA molecule. Unlike the nucleotide bases, which are planar and rigid, the sugar ring is easily bent and twisted into various conformations (which exist in different structural forms of DNA).

Nucleosides and Nucleotides.

The term “nucleoside” refers to a base and sugar. “Nucleotide,” on the other hand, refers to the base, sugar, and phosphate group (Figure 1). A bond, called the glycosidic bond, holds the base to the sugar and the 3′-5′ (“three prime-five prime”) phosphodiester bond holds the individual nucleotides together. Nucleotides are joined from the 3′ carbon of the sugar in one nucleotide to the 5′ carbon of the sugar of the adjacent nucleotide. The 3′ and the 5′ ends are chemically very distinct and have different reactive properties.

Unwound DNA.

Since A·T base pairs contain two hydrogen bonds and C·G base pairs contain three, A+T-rich tracts are less thermally stable that C+G-rich tracts in DNA. Under denaturing conditions (heat or alkali), the DNA begins to “melt” (separate), and unwound regions of DNA will form, and it is the A+T-rich sequences that melt first. In addition, in the presence of superhelical energy (a high-energy state of DNA resulting from its supercoiling, which is the natural form of DNA in the chromosomes of most organisms), A+T-rich regions can unwind and remain unwound under conditions normally found in the cell. Such sites often provide places for DNA replication proteins to enter DNA to begin the process of chromosome duplication.

Cruciform Structures.

DNA sequences are said to be palindromic when they contain inverted repeat symmetry, as in the sequence GGAATTAATTCC, reading from the 5′ to the 3′ end. Palindromic sequences can form intramolecular bonds (within a single strand), rather than the normal intermolecular (between the two complementary strands), hydrogen bonds. To form cruciforms (“cross-shaped”), the DNA must form a small unwound structure, and then base pairs must begin to form within each individual strand, thus forming the four-stranded cruciform structure.

the basic components of dna are

Slipped-Strand DNA.

Slipped-strand DNA structures can form within direct repeat DNA sequences, such as (CTG)_n·(CAG)_n and (CGG)_n·(CCG)_n (where “n” denotes a variable number of repetitions). They form following denaturation, after the strands become unwound, and during renaturation, when the strands come back together. To form slipped-strand DNA, the opposite strands come together in an out-of-alignment fashion, during renaturation. Expansion of such triplet repeats are features of certain neurological diseases.

Intermolecular Triplex DNA.

Three-stranded, or triplex DNA, can form within tracts of polypurine.polypyrimidine sequence, such as (GAA)_n·(TTC)_n. The important factor for triplex DNA formation is the presence of an extended purine tract in a single DNA strand. The third-strand base-pairing code is as follows: A can pair with A or T; G can pair with a protonated C (C⁺) or G.

Intramolecular Triplex DNA.

Random Posts

When a Pu·Py tract exists that has mirror repeat symmetry (5′ GAAGAG-GAGAAG 3′), an intramolecular triplex can form, in which half of the Pu.Py tract unwinds and one strand wraps into the major groove, forming a triplex. The structure in Figure 4 shows the pyrimidine strand (CTT) pairing with the purine strand (GAA) of a canonical DNA duplex. In an intramolecular triplex, one strand of the unwound region remains unpaired, as shown.

fateme hasani