Double Helix Structure Of Dna
Table of Contents
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[DNA Double Helix](#DNA Double Helix)
Who proposed this structure?
[DNA Replication](#DNA Replication)
[Frequently Asked Questions](#Frequently Asked Questions)
DNA Double Helix
A molecule of DNA is structured as a double helix, resembling a twisted staircase. The two strands are wound around each other like a twisted ladder, with a backbone of alternating phosphate and sugar groups. The nitrogenous bases are in the middle, connecting the two strands.
The base complementary rule states that adenine forms a base pairing with thymine, and cytosine pairs with guanine. This pairing is necessary for the two strands of DNA to be complementary to one another, as each of the four bases - (A) adenine, (G) guanine, (C) cytosine, and (T) thymine - is attached to each sugar.
The complementary strand of a sequence of TTGGCCAA should be AACCGGTT.
As a result of this base pairing, DNA strands are antiparallel, complementary to one another and running in opposite directions. That is to say, the 5′ carbon end of one of the strands faces the 3′ carbon end of its complementing strand. This orientation that runs antiparallel is crucial for replication of DNA and several nucleic acid interactions.
Each DNA strand in the double helix is linear and long, comprising smaller units known as nucleotides which form a chain when bonded together. The chemical bonds referred to as the sugar-phosphate backbones are created by the phosphate and sugar molecules.
See Also: DNA Ligase
Who proposed this structure?
In 1962, James Watson, Francis Crick and Maurice Wilkins were awarded the Nobel Prize for their pioneering work in 1953, in which they put forward the molecular structure of DNA - termed the “double helix” - in a journal. This breakthrough was a milestone in the history of medicine.
DNA Replication
During DNA replication, each strand of the DNA is copied, resulting in the formation of a daughter DNA double helix. This double helix consists of one parental DNA strand and one newly synthesized DNA strand. At this stage, there is a chance for a change in the sequence of the nitrogen base, which can result in a mutation.
The DNA often takes the initiative when mutation occurs, allowing it to repair itself and return to its original sequence. However, if repair is not feasible, new proteins are created.
To summarize, the unique structure of DNA allows molecules to copy themselves during the cell division process. When a cell is ready to divide, the DNA helix breaks into two and the single strands act as templates to build two new double-stranded DNA molecules, each of which is an exact replica of the original. This process is aided by the complementary base pairing of A (adenine) with T (thymine) and C (cytosine) with G (guanine). As a result, the bases now have partners once again.
During the formation of proteins, the double helix of DNA unwinds, allowing a single strand to act as a template. This template is then transcribed into mRNA, a molecule that carries important instructions to the cell’s protein-producing factory.
Frequently Asked Questions
The Watson and Crick Model of DNA is a double-helix structure proposed by James Watson and Francis Crick in 1953. It states that DNA is composed of two strands that are intertwined around each other. The strands are composed of four nucleotides (adenine, thymine, guanine, and cytosine), which form the “rungs” of the ladder-like structure.
Watson and Crick proposed the molecular structure of DNA, which they termed the “double helix”. A key feature of this model is the specific pairing of nucleotides; each DNA strand is linear and long, comprised of smaller units called nucleotides, which form a chain.
What is Chargaff’s Rule?
Chargaff’s Rule states that within a single strand of DNA, the number of adenine nucleotides is equal to the number of thymine nucleotides, and the number of guanine nucleotides is equal to the number of cytosine nucleotides.
According to Chargaff’s rule, the amount of A is equal to T, whereas the amount of C is equal to G. The DNA of any cell from any organism should have a 1:1 ratio of purine (A and G) and pyrimidine (C and T) bases.
