DNA ligase is an enzyme that repairs irregularities or breaks in the backbone of double-stranded DNA molecules. It has three general functions: It seals repairs in the DNA, it seals recombination fragments, and it connects Okazaki fragments (small DNA fragments formed during the replication of double-stranded DNA). DNA ligase functions by forming a bond between the end of a “donor” nucleotide and the end of an “acceptor” nucleotide.Continue Reading
There are two main types of DNA ligase — the first is found only in prokaryotic cells (cells with no nucleus, such as bacteria). The second is found in eukaryotic cells (cells with a nucleus, like those of plants and animals) as well as in viruses and bacteriophages. Furthermore, mammals have four subtypes of ligases that vary in their function; DNA ligase III, for example, contains a DNA repair protein, called XRCC1, that seals the break in the DNA strand that occurs during nucleotide excision repair. In general, eukaryotic DNA ligases are much larger than their prokaryotic counterparts; the smallest DNA ligase is produced by the bacteriophage T7.
Because DNA ligase plays such an important role in assisting with DNA repair and replication, it is an important component of genetic recombination experiments, including cloning.Learn more about Molecular Biology & DNA
Two components make the backbone in DNA, being the deoxy-ribose and phosphate molecules. These molecules link together in a staggered pattern where the deoxy-ribose and phosphate molecules follow one another, like the backbone of a zipper. Deoxy-ribose is a type of sugar molecule where the adenine, guanine, cytosine and thymine molecules attach a covalent bond. The phosphate molecules bond with the deoxy-ribose molecule acting like anchors in DNA.Full Answer >
The powerful enzyme DNA helicase unwinds the double strands of DNA by breaking the bonds between each of the complementary bases. These bases are held together by strong hydrogen bonds, but in breaking these, DNA helicase creates two single-stranded DNA molecules.Full Answer >
DNA has a slightly negative charge due to the presence of phosphate groups found in the sugar-phosphate backbone of a DNA molecule. In addition to a phosphate group, each nucleotide of a DNA molecule features a nitrogen-containing base and a five-carbon sugar.Full Answer >
DNA stores information in a sequence of adenine, cytosine, guanine and thymine on a backbone of two deoxyribose molecules, which intertwine in a double helix. In nature, this information is read by RNA molecules and turned into proteins.Full Answer >