Explain briefly (a) PCR (b) Restriction enzymes and DNA (c) Chitinase
PCR stands for Polymerase Chain Reaction. In this reaction, multiple copies of the gene (or DNA) of interest are synthesised in vitro. This method is used for the amplification of the gene of interest.
Restriction enzymes belong to a larger class of enzymes called nucleases. Exonucleases remove nucleotides from the ends of the DNA, whereas endonucleases make cuts at specific positions within the DNA. Each restriction endonuclease recognises a specific palindromic nucleotide sequence in the DNA. Once it finds this sequence, it binds to the DNA and cuts each of the two strands of the double helix at specific points in their sugar-phosphate backbones.
In order to cut DNA with restriction enzymes, it needs to be in pure form, free from other macromolecules. This requires breaking the cell open to release the DNA. Chitinase is the specific enzyme used to treat fungus cells to break them open and release the DNA along with other macromolecules.
Explanation
The answer is constructed strictly from the provided text. Part (a) uses the definition from section 9.3.3. Part (b) utilizes the definitions of nucleases, exonucleases, and endonucleases, along with the specific mechanism of restriction enzymes cutting the sugar-phosphate backbone at palindromic sequences. Part (c) is derived from the paragraph explaining the release of DNA from cells using specific enzymes like lysozyme for bacteria and chitinase for fungus.