Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
Try to explain the function of DNA gyrase with a drawing
DNA (deoxyribonucleic acid) gyrase is an essential enzyme present in bacteria. DNA gyrase belongs to the category of type II topoisomerases and is an ATP (adenosine triphosphate) driven enzyme. The presence of this enzyme is essential in bacteria in DNA synthesis. During the process of replication, it is necessary to form a single stranded DNA template to initiate DNA synthesis. Thus, the double stranded circular structure of the bacterial chromosome needs to be reshaped into a helical structure. DNA gyrase catalyzes this transformation of circular double stranded DNA into a helical form. The DNA gyrase is known to consist of gyrA gene that codes for the two A subunits and gyrB gene that codes for the two B subunits.
The functions of DNA gyrase are:
- Enables the negative-supercoiling (underwinding) of circular DNA by forming double stranded breaks.
- The two A subunits act as the blade of scissors which break and reseal the DNA whereas the two B subunits form the handle of the scissors, which is ATP driven component.
- The DNA gyrase forms covalent linkage with the 5’ end of the DNA and the tyrosine residue of A subunit.
- This covalent linkage cleaves the circular DNA and reseals it to form the DNA supercoiling.
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