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Four of these elements (hydrogen, carbon, nitrogen, and oxygen) are essential to every living thing and collectively make up 99% of the mass of protoplasm. [1] Phosphorus and sulfur are also common essential elements, essential to the structure of nucleic acids and amino acids, respectively.
Radioactive sulfur-35 was used to label the protein sections of the T2 phage, because sulfur is contained in protein but not DNA. [ 6 ] Hershey and Chase inserted the radioactive elements in the bacteriophages by adding the isotopes to separate media within which bacteria were allowed to grow for 4 hours before bacteriophage introduction.
Long DNA helices with a high GC-content have more strongly interacting strands, while short helices with high AT content have more weakly interacting strands. [28] In biology, parts of the DNA double helix that need to separate easily, such as the TATAAT Pribnow box in some promoters , tend to have a high AT content, making the strands easier ...
Nucleic acids RNA (left) and DNA (right). Nucleic acids are large biomolecules that are crucial in all cells and viruses. [1] They are composed of nucleotides, which are the monomer components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid ...
Contamination by phenol, which is commonly used in nucleic acid purification, can significantly throw off quantification estimates. Phenol absorbs with a peak at 270 nm and a A 260/280 of 1.2. Nucleic acid preparations uncontaminated by phenol should have a A 260/280 of around 2. [2]
Nucleic acids have a smaller percentage of hydrogen atoms, which are the atoms usually observed in NMR, and because nucleic acid double helices are stiff and roughly linear, they do not fold back on themselves to give "long-range" correlations. [3] The types of NMR usually done with nucleic acids are 1 H or proton NMR, 13 C NMR, 15 N NMR, and ...
Sulfur-35 is used to label proteins and nucleic acids. Cysteine is an amino acid containing a thiol group which can be labeled by sulfur-35. For nucleotides that do not contain a sulfur group, the oxygen on one of the phosphate groups can be substituted with a sulfur.
To cope with volume constraints, DNA can pack itself in the appropriate solution conditions with the help of ions and other molecules. Usually, DNA condensation is defined as "the collapse of extended DNA chains into compact, orderly particles containing only one or a few molecules". [ 3 ]