Structure of cytosine with and without the 5-methyl group. Deamination converts 5-methylcytosine into thymine. Base modifications and DNA packaging Further information: DNA methylation and Chromatin remodeling The expression of genes is influenced by how the DNA is packaged in chromosomes, in a structure called chromatin.
The discovery of the DNA double helix made clear that genes are functionally defined parts of DNA molecules, and that there must be a way for cells to translate the information in DNA to specific amino acids, which are used in order to make proteins.
Linus Pauling was a chemist who was very influential in developing an understanding of the structure of biological molecules. InPauling published the structure of the alpha helixa fundamentally important structural component of proteins.
In earlyPauling published a triple helix model of DNA, which subsequently turned out to be incorrect. DNA structure and function[ edit ] This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
Unsourced material may be challenged and removed. April Learn how and when to remove this template message It is not always the case that the structure of a molecule is easy to relate to its function. What makes the structure of DNA so obviously related to its function was described modestly at the end of the article: The two base-pair complementary chains of the DNA molecule allow replication of the genetic instructions.
The "specific pairing" is a key feature of the Watson and Crick model of DNA, the pairing of nucleotide subunits. G pairs are structurally similar. In particular, the length of each base pair is the same and they fit equally between the two sugar-phosphate backbones.
The base pairs are held together by hydrogen bondsa type of chemical attraction that is easy to break and easy to reform.
After realizing the structural similarity of the A: G pairs, Watson and Crick soon produced their double helix model of DNA with the hydrogen bonds at the core of the helix providing a way to unzip the two complementary strands for easy replication: Indeed, the base-pairing did suggest a way to copy a DNA molecule.
Just pull apart the two sugar-phosphate backbones, each with its hydrogen bonded A, T, G, and C components. Each strand could then be used as a template for assembly of a new base-pair complementary strand. Future considerations[ edit ] Watson and Crick used many aluminium templates like this one, which is the single base Adenine Ato build a physical model of DNA in When Watson and Crick produced their double helix model of DNA, it was known that most of the specialized features of the many different life forms on Earth are made possible by proteins.
Structurally, proteins are long chains of amino acid subunits. In some way, the genetic molecule, DNA, had to contain instructions for how to make the thousands of proteins found in cells.
From the DNA double helix model, it was clear that there must be some correspondence between the linear sequences of nucleotides in DNA molecules to the linear sequences of amino acids in proteins.
The details of how sequences of DNA instruct cells to make specific proteins was worked out by molecular biologists during the period from to Francis Crick played an integral role in both the theory and analysis of the experiments that led to an improved understanding of the genetic code.
The austere beauty of the structure and the practical implications of the DNA double helix combined to make Molecular structure of Nucleic Acids; A Structure for Deoxyribose Nucleic Acid one of the most prominent biology articles of the twentieth century.
Collaborators and controversy[ edit ] Main article: StokesMaurice Wilkinsand H. Key data from Wilkins, Stokes, and Wilson, and, separately, by Franklin and Goslingwere published in two separate additional articles in the same issue of Nature with the article by Watson and Crick.
InWatson published a highly controversial autobiographical account of the discovery of the double-helicalmolecular structure of DNA called The Double Helixwhich was not publicly accepted either by Crick or Wilkins.
In particular, in lateFranklin had submitted a progress report to the Medical Research Councilwhich was reviewed by Max Perutzthen at the Cavendish Laboratory of the University of Cambridge.
By NovemberWatson had acquired little training in X-ray crystallography, by his own admission, and thus had not fully understood what Franklin was saying about the structural symmetry of the DNA molecule.
Crick was thus in a unique position to make this interpretation because he had formerly worked on the X-ray diffraction data for other large molecules that had helical symmetry similar to that of DNA. Franklin, on the other hand, rejected the first molecular model building approach proposed by Crick and Watson: Watson explicitly admitted this in his book The Double Helix.The structure of DNA and RNA.
DNA is a double helix, while RNA is a single helix. Both have sets of nucleotides that contain genetic information. according to a report by the National Human. According to Wilkins (~. rhe structure is now firmly established.
The detailed structure described by Crick and Watson (8) has been shown to have too large a diameter, and a drawing has been given of an improved model which is in fairly good agreement with the s-ray data. View Lab Report - Biology Lab 8 Lab Report from BIOLOGY at Dallas County Community College.
BioLab3 Lab Report 8 DNA Structure and Function Student Name: Isaac Geisinger I. DNA Find Study Resources%(14). This lab was done to have a visual representation of the structure of DNA. This visual representation is important so that an image of what DNA looks like can be obtained and all other matters concepts with DNA and RNA can be visualized, leading to a better and .
View Lab Report - Structure of DNA Lab Report from BSC L at University of South Florida.
Within chromosomes, DNA is held in complexes with structural proteins. These proteins organize the DNA into a compact structure called chromatin.
In eukaryotes, this structure involves DNA binding to a complex of small basic proteins called histones, while in prokaryotes multiple types of .