Guide To Learn
The term restriction endonuclease was coined by Lederberg and Meselson in 1964 to describe the nuclease enzyme that destroys or restricts any foreign DNA entering a bacterial cell. These restriction endonucleases are widely used in rDNA technology. They specifically bind to double-stranded DNA and cleave it at specific sites known as recognition sequence or restriction […]
The basic tools of rDNA technology include various:
The first step in the rDNA technology is the isolation of the desired gene of interest for which the DNA from the cell has been isolated. DNA Isolation DNA can be isolated by employing gentle methods of cell rupture. Cell walls if present are digested enzymatically (lysozyme treatment) and the cell membrane is solubilized using […]
Recombinant DNA (rDNA) technology deals with the isolation and manipulation of DNA. DNA molecules from all organisms share the same chemical structure; they differ only in the sequence of nucleotides, consequently, a DNA from a foreign source can be linked to host DNA sequences, i.e., the DNAs of two different species can be linked to […]
Oncogenes are genes that induce cancer in animals. Their normal cellular counterparts are called ‘proto-oncogenes’. Mutations in two broad classes of genes namely proto-oncogenes and tumour-suppressor genes play a significant role in the development of cancer. The oncogenes produced by the mutations of proto-oncogenes encode oncoproteins that mediate the pathogenesis. In certain cases, the oncogenes […]
The integrity of the DNA is very much important for the sustainability of the cell. For this reason, a vast number of repair systems work efficiently debugging the errors. The repair process begins during replication and continues in various forms even during the post-replication. About 130 repair genes exist in human genome that codes for […]
Mutagens can even affect the chromosomes. The chromosomal changes can be either involving their structure or their number. The numerical changes are referred to as ‘ploidy’. It can be detected as ‘aneupoidy’ and ‘polyploidy’. The structural abnormalities include ‘deletions’, ‘duplications’, ‘inversions’, and ‘translocations’. These changes in the structure and the number of the chromosome are […]
Chemical Mutagens Mutations can be caused by chemicals such as: Base analogues Compounds that resemble the four bases of nucleic acids are called base analogues for example, 5-bromouracil and 2-amino purine. These base analogues can be incorporated into DNA. They lead to transition mutations (purine to purine) as a consequence of altered base pairing in […]
‘Mutation’ refers to heritable changes in the base sequence of the DNA. The most common types of change are a substitution, an addition or a deletion of one or more bases. A physical or chemical agent that causes or increases the frequency of mutation is called a ‘mutagen’. The process of producing a mutation is […]
Endogenous DNA Damages There are five main types of damage to DNA due to endogenous cellular processes (Figure 8.2). These include: Spontaneous damages can include the loss of a base, deamination, sugar ring puckering and tautomeric shifts. Figure 8.2 Types of DNA damages When compared to the nuclear DNA, the mitochondrial DNA is more […]