Principles of genetic

Genetic engineering deliberately manipulates genetic material, often by transferring a gene into an organism. This transfer results in the expression of the new gene, leading to altered or novel characteristics in the modified organism, e.g. using bacteria to produce human insulin.

Genes can be obtained by: 1. Extracting DNA directly from a donor organism. 2. Synthesising DNA from the mRNA of a donor organism using reverse transcriptase. 3. Synthesising DNA chemically from individual nucleotides.

Restriction endonucleases cut DNA at specific recognition sequences, creating defined fragments. These enzymes are crucial for isolating the desired gene from a donor organism and for opening up a plasmid vector to receive the gene.

A promoter region is essential for initiating transcription of the gene. If the host organism's cellular machinery does not recognize the gene's native promoter, the gene will not be expressed without the addition of a compatible promoter.

Marker genes, such as those coding for fluorescent proteins (

PCR is a technique used to amplify a specific DNA sequence. Taq polymerase is a heat-stable DNA polymerase that extends DNA from primers, creating multiple copies of the target sequence through repeated cycles of heating and cooling.

Gel electrophoresis separates DNA fragments based on size. Smaller fragments migrate through the gel matrix faster than larger fragments. This allows for visualization and analysis of DNA fragment sizes after staining.

Microarrays contain thousands of DNA probes corresponding to different genes. mRNA is extracted from a cell, converted to cDNA, labeled, and hybridized to the microarray. The amount of cDNA bound to each spot reveals the expression level of the corresponding gene.