The below mentioned article provides notes on DNA methylation. The DNA of many higher eukaryotes is modified after replication by methylation of cytosine bases at the 5-carbon position. The cytosines are incorporated in their normal unmodified form in the course of DNA replication; the methyl group (CH3) is then added by an enzyme DNA methylase. In mammals DNA is methylated [...]
In this article we will discuss about the five main DNA repair mechanisms that are studied in eukaryotes. The mechanisms are: 1. Photo-Reactivation or Photo-Repair 2. Dark or Excision Repair 3. Nucleotide Excision Repair 4. Mismatch Repair 5. Post-Replication Repair. Mechanism # 1. Photo-Reactivation or Photo-Repair: This mechanism was discovered when bacteria that had been heavily irradiated with UV rays [...]
In eukaryotic organisms — plants, animals and fungi — the major portion of DNA is present in the chromosomes which are well-organised structures and quite different from the prokaryotic counterparts. Besides the chromosomes, mitochondria of both plants and animals and the chloroplasts of green plants also contain DNA. Interesting is the fact that the organization and the nature of the [...]